Understanding and explaining technical topics from low-level fundamental principles.https://pavelhan.tech/enhttps://pavelhan.tech/en/article/2026-10-22-the-summary-of-eSIM/https://pavelhan.tech/en/article/2026-10-22-the-summary-of-eSIM/eSIM from 5G RedCap module practice: form factors, LPA architecture, profile download, dynamic switching, cross-region fallback and the RSP provisioning flow.Thu, 22 Oct 2026 00:00:00 GMThttps://pavelhan.tech/en/article/2026-07-22-the-webhooks-and-http-push-feature-of-security-camera/https://pavelhan.tech/en/article/2026-07-22-the-webhooks-and-http-push-feature-of-security-camera/This article introduces the Webhooks and HTTP Push features supported by some security camera products for third-party alarm platforms, along with the implementation architecture and communication workflow best practices.Wed, 22 Jul 2026 00:00:00 GMThttps://pavelhan.tech/en/article/2026-07-15-the-summary-of-5G-LTE-work-mode/https://pavelhan.tech/en/article/2026-07-15-the-summary-of-5G-LTE-work-mode/Power management of 5G and LTE modules is a core component in hardware design and BSP driver development. To strike a balance between responding to the network at any time and maximizing power savings, these modules typically follow 3GPP specifications combined with hardware interfaces, resulting in several tiered working modes. This article summarizes these working modes.Wed, 15 Jul 2026 00:00:00 GMThttps://pavelhan.tech/en/article/2026-07-08-How-the-point-cloud-data-of-mmwave-radar-built/https://pavelhan.tech/en/article/2026-07-08-How-the-point-cloud-data-of-mmwave-radar-built/This article explains how point cloud data from millimeter wave radar is constructed, focusing on radar chip and module output.Wed, 08 Jul 2026 00:00:00 GMThttps://pavelhan.tech/en/article/2026-07-02-How-to-measure-the-angle-information-mmsense-radar/https://pavelhan.tech/en/article/2026-07-02-How-to-measure-the-angle-information-mmsense-radar/An overview of how millimeter-wave (mmWave) radar measures and calculates angle information.Thu, 02 Jul 2026 00:00:00 GMThttps://pavelhan.tech/en/article/2026-07-01-the-detailed-summary-of-mmWave-sensing-workflow-and-calculation/https://pavelhan.tech/en/article/2026-07-01-the-detailed-summary-of-mmWave-sensing-workflow-and-calculation/A detailed breakdown of FMCW (Frequency Modulated Continuous Wave) mmWave radar: how chirp signals are organized, mixing and IF signal generation, the range FFT and Doppler FFT solving flow, and how a range-Doppler map is built for multi-target scenarios.Wed, 01 Jul 2026 00:00:00 GMThttps://pavelhan.tech/en/article/2026-06-29-the-priciple-and-application-of-mmwave-sensing/https://pavelhan.tech/en/article/2026-06-29-the-priciple-and-application-of-mmwave-sensing/In essence, radar (originally an acronym for 'radio detection and ranging') is a device that detects a target's distance, velocity, and direction by transmitting electromagnetic waves (radio waves) towards it and then measuring the reflected radio waves.Mon, 29 Jun 2026 00:00:00 GMThttps://pavelhan.tech/en/article/2026-06-24-the-compatibility-issue-between-DDR-and-LPDDR/https://pavelhan.tech/en/article/2026-06-24-the-compatibility-issue-between-DDR-and-LPDDR/Are DDR and LPDDR mutually compatible during system design? For a main host SoC, how can you make the right selection and design choices between DDR and LPDDR? This article attempts to explain and summarize these DDR and LPDDR compatibility issues in detail.Wed, 24 Jun 2026 00:00:00 GMThttps://pavelhan.tech/en/article/2026-06-22-the-comprehensive-summary-of-NFC/https://pavelhan.tech/en/article/2026-06-22-the-comprehensive-summary-of-NFC/NFC (Near Field Communication) is a high-frequency RFID (Radio Frequency Identification) technology widely used in today's consumer electronics. This article provides a comprehensive summary of the foundational theory and application knowledge of this technology, helping to establish a basic understanding of NFC.Mon, 22 Jun 2026 00:00:00 GMThttps://pavelhan.tech/en/article/2026-06-15-How-to-calculate-the-internal-junction-temperature-in-chips/https://pavelhan.tech/en/article/2026-06-15-How-to-calculate-the-internal-junction-temperature-in-chips/Focusing on common thermal design issues in electronic products, this article provides a detailed compilation of temperature, thermal resistance, and other parameters provided in component datasheets, as well as the calculation process for internal junction temperature using these parameters. It establishes a theoretical foundation for subsequent hardware system design, chip selection, and thermal design parameter testing and estimation in electronic products.Mon, 15 Jun 2026 00:00:00 GMThttps://pavelhan.tech/en/article/2026-06-12-How-to-understand-AI-DLC/https://pavelhan.tech/en/article/2026-06-12-How-to-understand-AI-DLC/When using AI development tools like Claude Code, Trae, or Cursor, many developers often fall into the trap of casual coding (so-called Vibe Coding):Fri, 12 Jun 2026 00:00:00 GMThttps://pavelhan.tech/en/article/2026-06-10-The-summary-of-AWS-cloudfront-service/https://pavelhan.tech/en/article/2026-06-10-The-summary-of-AWS-cloudfront-service/Amazon CloudFront Service is positioned as AWS's global Content Delivery Network (CDN) service (currently generally available/GA across all AWS Regions). Its core function is to cache static resources and accelerate the transmission and distribution of both static and dynamic content through AWS's globally deployed backbone network.Wed, 10 Jun 2026 00:00:00 GMThttps://pavelhan.tech/en/article/2026-05-05-the-detailed-explanation-of-FP16-and-INT8-quantization-workflow/https://pavelhan.tech/en/article/2026-05-05-the-detailed-explanation-of-FP16-and-INT8-quantization-workflow/This article provides a comprehensive summary of the concepts and calculation workflows for half-precision floating-point conversion (FP16) and fixed-point quantization (INT8) applied to models trained in frameworks like PyTorch.Fri, 05 Jun 2026 00:00:00 GMThttps://pavelhan.tech/en/article/2026-06-01-the-example-of-Gitops-driven-AWS-cloud-application-development-and-deployment/https://pavelhan.tech/en/article/2026-06-01-the-example-of-Gitops-driven-AWS-cloud-application-development-and-deployment/This article demonstrates the complete workflow of code development, testing, and automated deployment in production environments on AWS using GitOps principles, through a simple Python project. The general requirements of this case are: • The local client sends an HTTP request (containing a file name string in the request message) to AWS API Gateway; • AWS Gateway receives it and forwards it to Lambda; • Lambda creates a file in S3 based on the file name and returns a message to the client.Mon, 01 Jun 2026 00:00:00 GMThttps://pavelhan.tech/en/article/2026-05-29-how-PSRAM-and-LPDDR-reduce-its-power-consumption/https://pavelhan.tech/en/article/2026-05-29-how-PSRAM-and-LPDDR-reduce-its-power-consumption/Due to the inherent self-refresh characteristic of DRAM and the processing of high-frequency communication signals, DDR has always been a major power consumer in electronic system design. This article focuses on summarizing the targeted design strategies implemented by LPDDR and PSRAM to reduce power consumption.Fri, 29 May 2026 00:00:00 GMThttps://pavelhan.tech/en/article/2026-05-27-Can-PSRAM-replace-DDR/https://pavelhan.tech/en/article/2026-05-27-Can-PSRAM-replace-DDR/With the current tight supply and drastic price fluctuations in the DDR memory market, some SoC vendors in the IPC field have started promoting Camera SoC platforms with built-in PSRAM. What are the differences between PSRAM and the DDR we commonly use, and what applications are they suitable for? This article attempts to clearly answer these questions.Wed, 27 May 2026 00:00:00 GMThttps://pavelhan.tech/en/article/2026-05-23-the-workflow-and-security-solution-of-stripe/https://pavelhan.tech/en/article/2026-05-23-the-workflow-and-security-solution-of-stripe/In the web world, handling user credit card numbers during online payment processes is an extremely high-risk operation. For full-stack developers implementing overseas business scenarios within their applications, they must deal with cross-border credit card network communications, 3D Secure dynamic authentication, and strict PCI-DSS security compliance audits. To address this challenge, Stripe emerged. Its brilliance lies in encapsulating chaotic real-world capital flows into highly predictable, developer-friendly interfaces through exceptionally elegant RESTful APIs and a webhook-based asynchronous event-driven model. Under this architecture, developers' own servers never need to touch, transmit, or store the user's real credit card numbers in plaintext; they simply send instructions to Stripe, and Stripe returns a token indicating the execution result after processing, greatly simplifying the complexity of payment operations.Sat, 23 May 2026 00:00:00 GMThttps://pavelhan.tech/en/article/2026-05-16-the-serveral-issues-in-the-RAG-workflow/https://pavelhan.tech/en/article/2026-05-16-the-serveral-issues-in-the-RAG-workflow/This article briefly summarizes the overall workflow and module decomposition of Retrieval-Augmented Generation (RAG) systems, and clarifies several issues related to the RAG workflow, vector data storage, and vector retrieval.Sat, 16 May 2026 00:00:00 GMThttps://pavelhan.tech/en/article/2026-05-13-the-summary-of-network-structure-and-output-of-YOLOv8-Pose/https://pavelhan.tech/en/article/2026-05-13-the-summary-of-network-structure-and-output-of-YOLOv8-Pose/Compares the network structure of YOLOv8-Pose and standard YOLOv8, focusing on the keypoint branch design of the Pose detection head, the meaning of each output tensor dimension, post-processing filters, and how keypoint coordinates are decoded from the raw output.Wed, 13 May 2026 00:00:00 GMThttps://pavelhan.tech/en/article/2026-05-11-the-summary-of-KV-cache-workflow-in-LLM/https://pavelhan.tech/en/article/2026-05-11-the-summary-of-KV-cache-workflow-in-LLM/By describing the interaction process between agents and large language models (LLMs), this article explains in detail the difference between Input Tokens and Cached Tokens. Understanding this distinction makes it easy to grasp the differences in computing power requirements and pricing between these two types of tokens. When purchasing token quotas from various LLM vendors, we often see three different prices: input price (cache hit), input price (cache miss), and output price. While the concepts of input and output tokens are straightforward, what is the difference between cache hit and cache miss here? Similarly, when using various agents such as Claude Code or Gemini CLI, upon exiting a session, the agent outputs usage statistics for input tokens, cached tokens, and output tokens. What exactly is the difference between Input Tokens and Cache Reads here?Mon, 11 May 2026 00:00:00 GMThttps://pavelhan.tech/en/article/2026-05-07-the-lambda-service-in-amazon-aws/https://pavelhan.tech/en/article/2026-05-07-the-lambda-service-in-amazon-aws/AWS Lambda is a fully managed serverless compute service. Compared to traditional Java/Python/Node.js services based on EC2 and resident processes, when handling identical application requirements with Lambda, developers only need to upload their code to the server, and AWS automatically provisions the required compute resources, releasing them immediately after code execution. This article summarizes various concepts related to the AWS Lambda Service.Thu, 07 May 2026 00:00:00 GMThttps://pavelhan.tech/en/article/2026-05-02-the-detailed-explanation-of-the-concept-and-workflow-of-BNNorm-in-CNN/https://pavelhan.tech/en/article/2026-05-02-the-detailed-explanation-of-the-concept-and-workflow-of-BNNorm-in-CNN/This article provides a detailed summary of the theoretical significance of Batch Normalization (BN), which is ubiquitous in various convolutional neural network architectures, and the workflow of BN layer calculations in various computer vision network models.Sat, 02 May 2026 00:00:00 GMThttps://pavelhan.tech/en/article/2026-04-29-how-to-convert-PT-model-to-LiteRT-format/https://pavelhan.tech/en/article/2026-04-29-how-to-convert-PT-model-to-LiteRT-format/Previously, when attempting to run Ultralytics' YOLOv8 model on Android phones (refer toWed, 29 Apr 2026 00:00:00 GMThttps://pavelhan.tech/en/article/2026-04-28-how-to-handle-the-opset-version-and-compatility-issue-in-tflite/https://pavelhan.tech/en/article/2026-04-28-how-to-handle-the-opset-version-and-compatility-issue-in-tflite/When performing model deployment and on-device adaptation on Rockchip NPU platforms, consistency between the Opset version specified during ONNX export and the Opset version supported by the on-device model conversion tool (RKNN-Toolkit2) is crucial. If the conversion tool does not support certain operator types in the ONNX file, the conversion process will fail. So, does TFLite also suffer from Opset version issues?Tue, 28 Apr 2026 00:00:00 GMThttps://pavelhan.tech/en/article/2026-04-27-the-summary-of-YOLO-modal-workflow-in-android-flutter-project/https://pavelhan.tech/en/article/2026-04-27-the-summary-of-YOLO-modal-workflow-in-android-flutter-project/Previously, I implemented image object detection in an Android app by calling a YOLO model using Flutter. This article summarizes the complete execution workflow, covering the TFLite export of the YOLO model and its integration within an Android Flutter project. Running AI models on Android typically involves exporting the model file to the TFLite format and executing the inference pipeline under the Android TFLite+Interpreter+NCAPI framework. For background knowledge related to this framework, refer to...Mon, 27 Apr 2026 00:00:00 GMThttps://pavelhan.tech/en/article/2026-04-26-How-to-understand-the-core-concept-and-workflow-of-TFLite/https://pavelhan.tech/en/article/2026-04-26-How-to-understand-the-core-concept-and-workflow-of-TFLite/This article organizes the core concepts of TFLite, compares it with the ONNX framework, and examines the key workflows of its internal components, aiming to build a comprehensive understanding of the overall concept and workflow of this standard AI inference framework on Android.Sun, 26 Apr 2026 00:00:00 GMThttps://pavelhan.tech/en/article/2026-04-24-the-introduction-of-hands-landmarks-detection-model-MediaPipe-Hand-Landmarker/https://pavelhan.tech/en/article/2026-04-24-the-introduction-of-hands-landmarks-detection-model-MediaPipe-Hand-Landmarker/Google's MediaPipe Hand Landmarker is currently one of the most popular and efficient computer vision models for hand landmark detection.Fri, 24 Apr 2026 00:00:00 GMThttps://pavelhan.tech/en/article/2026-04-23-the-research-information-of-AWS-Bedrock/https://pavelhan.tech/en/article/2026-04-23-the-research-information-of-AWS-Bedrock/An overview of Amazon Bedrock: unified serverless APIs for foundation models from Anthropic, Meta, Mistral and others, cross-region inference routing, knowledge bases and agents, plus how Bedrock differs from SageMaker and Amazon Q.Thu, 23 Apr 2026 00:00:00 GMThttps://pavelhan.tech/en/article/2026-04-22-the-suammry-of-dual-band-wifi-and-BT-concurrent-communication-technology/https://pavelhan.tech/en/article/2026-04-22-the-suammry-of-dual-band-wifi-and-BT-concurrent-communication-technology/During the evolution of Wi-Fi products, Dual Band (2.4GHz and 5GHz) has become a very common and frequently used term. In communication, whether the two frequency bands are multiplexed/switched via time-sharing or can directly achieve dual-band concurrent communication forms two completely different working logics. This article attempts to explain this issue from the perspective of RF link multiplexing and concurrent processing logic.Wed, 22 Apr 2026 00:00:00 GMThttps://pavelhan.tech/en/article/2026-04-20-the-description-of-human-face-recognition-workflow-based-on-insightface/https://pavelhan.tech/en/article/2026-04-20-the-description-of-human-face-recognition-workflow-based-on-insightface/This article details the workflow of face recognition in computer vision, and provides a code-level demonstration and explanation using InsightFace, a complete face detection and recognition solution.Mon, 20 Apr 2026 00:00:00 GMThttps://pavelhan.tech/en/article/2026-04-17-the-training-process-and-the-deployment-on-RK3588-of-Baidu-RTDETRv2/https://pavelhan.tech/en/article/2026-04-17-the-training-process-and-the-deployment-on-RK3588-of-Baidu-RTDETRv2/The official GitHub repository for Baidu's RT-DETRv2 model is:Fri, 17 Apr 2026 00:00:00 GMThttps://pavelhan.tech/en/article/2026-04-15-the-training-process-and-deployment-on-RK3588-of-RTDETR/https://pavelhan.tech/en/article/2026-04-15-the-training-process-and-deployment-on-RK3588-of-RTDETR/This article provides a complete record of training the RT-DETR pre-trained model based on the Ultralytics project using a custom dataset, exporting it to ONNX, and adapting it for the RK3588 hardware platform. For the implementation of the RT-DETR model, there are currently two independent implementations: Baidu's PaddleDetection and Ultralytics (YOLOv8/v11 ecosystem). Since I am more familiar with Ultralytics/YOLO, this article uses the Ultralytics/YOLO implementation for experimentation and documentation.Wed, 15 Apr 2026 00:00:00 GMThttps://pavelhan.tech/en/article/2026-04-14-the-detailed-explanation-of-RTDETR-network-and-workflow/https://pavelhan.tech/en/article/2026-04-14-the-detailed-explanation-of-RTDETR-network-and-workflow/This article provides a detailed introduction to the network structure of RT-DETR, a Transformer-based image object detection model proposed by Baidu, along with its data computation workflow.Tue, 14 Apr 2026 00:00:00 GMThttps://pavelhan.tech/en/article/2026-04-13-the-detailed-summary-of-Google-EddyStone-BLE-advertising-protocol/https://pavelhan.tech/en/article/2026-04-13-the-detailed-summary-of-Google-EddyStone-BLE-advertising-protocol/Eddystone is a data format specifically defined for Bluetooth Low Energy (BLE) advertising packets. Introduced by Google as an open-source beacon protocol in 2015, it aims to provide an open and feature-rich advertising standard compared to Apple's iBeacon.Mon, 13 Apr 2026 00:00:00 GMThttps://pavelhan.tech/en/article/2026-04-08-how-to-understand-the-opset-version-in-ONNX-export-process/https://pavelhan.tech/en/article/2026-04-08-how-to-understand-the-opset-version-in-ONNX-export-process/When exporting a PyTorch-trained model from a PC or server to the ONNX format, you need to configure the opset version in the export script. Different opset versions heavily impact the subsequent NPU adaptation process. So what exactly is an opset version? What are the differences between opset versions, and how do these differences affect subsequent NPU adaptation? This article attempts to answer these questions.Wed, 08 Apr 2026 00:00:00 GMThttps://pavelhan.tech/en/article/2026-04-04-the-porting-of-PANNs-audio-tagging-model-on-rk3588/https://pavelhan.tech/en/article/2026-04-04-the-porting-of-PANNs-audio-tagging-model-on-rk3588/A complete record of porting a PANNs audio classification model (CNN14 architecture) trained on the ECS50 dataset to the Rockchip RK3588 platform: model conversion, rknn-toolkit-lite2 setup, and on-board inference with Python scripts.Sat, 04 Apr 2026 00:00:00 GMThttps://pavelhan.tech/en/article/2026-04-01-how-to-use-flitter_litert-plugin-run-tflite-model-on-android/https://pavelhan.tech/en/article/2026-04-01-how-to-use-flitter_litert-plugin-run-tflite-model-on-android/To convert a custom model into the TFLite format and run it smoothly inside an Android APP, a more flexible approach is required. This process consists of two main steps: converting the custom model's pt file to the TFLite format.Wed, 01 Apr 2026 00:00:00 GMThttps://pavelhan.tech/en/article/2026-04-01-the-training-process-of-PANNs-audio-tagging-model-using-ECS50-dataset/https://pavelhan.tech/en/article/2026-04-01-the-training-process-of-PANNs-audio-tagging-model-using-ECS50-dataset/This article documents the complete workflow for custom training of the audio detection and classification model PANNs using the ESC-50 dataset.Wed, 01 Apr 2026 00:00:00 GMThttps://pavelhan.tech/en/article/2026-03-28-the-summary-of-audio-FFT-calculation-workflow-and-spectrum-diagram/https://pavelhan.tech/en/article/2026-03-28-the-summary-of-audio-FFT-calculation-workflow-and-spectrum-diagram/This article summarizes the principles, parameters, and calculation workflows for performing FFT on speech signal sequences to obtain their corresponding spectra. It also provides a Python example to compute and interpret the spectrogram of a WAV file.Sat, 28 Mar 2026 00:00:00 GMThttps://pavelhan.tech/en/article/2026-03-26-the-summary-of-audio-tagging-model-PANNs/https://pavelhan.tech/en/article/2026-03-26-the-summary-of-audio-tagging-model-PANNs/This article organizes the basic information of the classic audio classification model PANNs, its model architecture, the classification of pre-trained parameter files, the setup of the development environment, basic inference testing, and explains the network architecture of its flagship CNN14 model.Thu, 26 Mar 2026 00:00:00 GMThttps://pavelhan.tech/en/article/2026-03-25-the-detailed-summary-of-the-deformable-conv-workflow/https://pavelhan.tech/en/article/2026-03-25-the-detailed-summary-of-the-deformable-conv-workflow/Regarding the calculation workflow of standard convolution kernels in convolutional neural networks...Wed, 25 Mar 2026 00:00:00 GMThttps://pavelhan.tech/en/article/2026-03-23-the-full-stack-development-environment-of-android-studio-and-flutter/https://pavelhan.tech/en/article/2026-03-23-the-full-stack-development-environment-of-android-studio-and-flutter/This article provides a comprehensive guide on setting up a full-stack development environment based on Android Studio and Flutter on Windows. The process itself is not overly complex, but due to the numerous concepts involved and network restrictions in mainland China when accessing Google servers, several points require attention during the initial setup and testing. This record serves as a complete reference for future development.Mon, 23 Mar 2026 00:00:00 GMThttps://pavelhan.tech/en/article/2026-03-21-the-deployment-process-of-Qwen3VL-on-RK3588/https://pavelhan.tech/en/article/2026-03-21-the-deployment-process-of-Qwen3VL-on-RK3588/This article provides a detailed log of the complete adaptation process for the Qwen3-VL-4B-Instruct multimodal large model on Rockchip RK3588, along with key considerations and common pitfalls during adaptation.Sat, 21 Mar 2026 00:00:00 GMThttps://pavelhan.tech/en/article/2026-03-18-the-summary-of-DETR-network-structure-and-workflow/https://pavelhan.tech/en/article/2026-03-18-the-summary-of-DETR-network-structure-and-workflow/This article provides a detailed introduction to the network structure and data computational workflow of DETR, an image object detection model based on the Transformer architecture proposed by Facebook in 2020.Wed, 18 Mar 2026 00:00:00 GMThttps://pavelhan.tech/en/article/2026-03-16-the-Qwen2.5-0.5B-model-deployment-on-RK3588https://pavelhan.tech/en/article/2026-03-16-the-Qwen2.5-0.5B-model-deployment-on-RK3588This article provides a detailed study and summary of Rockchip's RKLLM tool and its official related guidance documents, documenting the complete process and precautions for adapting the lightweight large language model Qwen2.5-0.5B to the RK3588. Overall, deploying an LLM on the Rockchip NPU follows the same core logic and workflow as deploying YOLO: PC-side model conversion -> pushing the model and libraries to the board -> calling the API to run.Mon, 16 Mar 2026 00:00:00 GMThttps://pavelhan.tech/en/article/2026-03-11-the-development-environment-of-RK3588-NPU/https://pavelhan.tech/en/article/2026-03-11-the-development-environment-of-RK3588-NPU/This article details setting up the NPU development and on-board inference environment on the Rockchip platform based on RK3588 + Debian Linux, using the YOLOv5 model from the Model Zoo as an example to summarize the end-to-end deployment workflow.Wed, 11 Mar 2026 00:00:00 GMThttps://pavelhan.tech/en/article/2026-03-09-the-summary-of-the-structure-and-workflow-of-transformer-decoder/https://pavelhan.tech/en/article/2026-03-09-the-summary-of-the-structure-and-workflow-of-transformer-decoder/This article provides a detailed summary of the overall network architecture of the Decoder part in the Transformer model, along with the data operations and flow processes within it.Mon, 09 Mar 2026 00:00:00 GMThttps://pavelhan.tech/en/article/2026-03-04-the-test-and-deployment-workflow-on-Qwen3VL/https://pavelhan.tech/en/article/2026-03-04-the-test-and-deployment-workflow-on-Qwen3VL/This article provides a brief overview of the Qwen3-VL vision-language model released by Alibaba in September 2025, and summarizes the workflow for local inference testing of its pretrained model and deployment using vLLM in a production environment.Wed, 04 Mar 2026 00:00:00 GMThttps://pavelhan.tech/en/article/2026-03-03-the-best-study-practice-of-open-source-software/https://pavelhan.tech/en/article/2026-03-03-the-best-study-practice-of-open-source-software/When performing secondary development or preliminary research on active and frequently updated open-source software on GitHub (such as Ultralytics), the most frustrating challenge is that upstream code in the source repository is constantly changing, while my own modifications during study and research are scattered everywhere. Eventually, I lose track of what I changed, leading to massive merge conflicts that are extremely inefficient to resolve. Based on online learning and research, this article presents a rational technical path to solve these problems. This workflow is a standard practice adopted by many teams during open-source project research. In short: ...Tue, 03 Mar 2026 00:00:00 GMThttps://pavelhan.tech/en/article/2026-03-02-the-step-by-step-implementation-of-a-simple-ViT-modal/https://pavelhan.tech/en/article/2026-03-02-the-step-by-step-implementation-of-a-simple-ViT-modal/This article focuses on the task of recognizing the simple MNIST handwritten digit dataset, completing the implementation, training, and validation of a minimal Vision Transformer model to build a comprehensive understanding of the ViT implementation workflow. The MNIST handwritten digit dataset is the simplest computer vision dataset. Implementing a Vision Transformer to recognize handwritten characters on MNIST is not overly difficult, and the data and computational requirements for model training are minimal. Therefore, training a ViT recognition model on the MNIST dataset serves as an excellent introductory experiment for learning Vision Transformers.Mon, 02 Mar 2026 00:00:00 GMThttps://pavelhan.tech/en/article/2026-02-25-the-strcture-of-ViT-Modal/https://pavelhan.tech/en/article/2026-02-25-the-strcture-of-ViT-Modal/This article provides a detailed summary of the Vision Transformer (ViT) model architecture and the complete image processing workflow within it, helping to build a foundational understanding of the ViT model. While the Transformer architecture has been widely adopted across various Large Language Models in Natural Language Processing (NLP), Google's milestone 2020 paper 'An Image is Worth 16×16 Words' introduced the Transformer to computer vision. By leveraging Patch Embedding and self-attention mechanisms, it has profoundly challenged the traditional dominance of Convolutional Neural Networks (CNNs) in computer vision, signaling a unifying trend across all domains of artificial intelligence.Wed, 25 Feb 2026 00:00:00 GMThttps://pavelhan.tech/en/article/2026-02-23-how-to-understand-multi-head-attention-in-transformer/https://pavelhan.tech/en/article/2026-02-23-how-to-understand-multi-head-attention-in-transformer/This article provides a detailed summary of the working principles and computational flow behind self-attention and multi-head self-attention in the Transformer architecture, aiming to foster a deeper understanding of the complete Transformer design.Mon, 23 Feb 2026 00:00:00 GMThttps://pavelhan.tech/en/article/2026-02-22-transformer-encoder-structure-and-workflow/https://pavelhan.tech/en/article/2026-02-22-transformer-encoder-structure-and-workflow/This article provides a detailed summary of the Encoder network architecture and its data flow computation workflow, using a standard Encoder-Only Transformer architecture as an example.Sun, 22 Feb 2026 00:00:00 GMThttps://pavelhan.tech/en/article/2026-02-11-the-summary-of-YOLOv5-loss-function/https://pavelhan.tech/en/article/2026-02-11-the-summary-of-YOLOv5-loss-function/Based on the v6.0/v6.1 version of the YOLOv5 model, this article provides a detailed summary and explanation of the calculation workflow for each part of the loss function.Wed, 11 Feb 2026 00:00:00 GMThttps://pavelhan.tech/en/article/2026-02-10-the-background-information-of-YOLOv5-loss-function/https://pavelhan.tech/en/article/2026-02-10-the-background-information-of-YOLOv5-loss-function/Based on versions v6.0/v6.1 of the YOLOv5 model, this article provides a detailed summary and explanation of the loss function calculation workflow and the background knowledge involved in its code implementation.Tue, 10 Feb 2026 00:00:00 GMThttps://pavelhan.tech/en/article/2026-02-09-SAM3-model-development-environment-and-video-segmentation-test/https://pavelhan.tech/en/article/2026-02-09-SAM3-model-development-environment-and-video-segmentation-test/This article provides a detailed record of setting up the environment for SAM3, the open-source image segmentation model released by Meta in November 2025, and walks through the process of performing image and video segmentation based on its official samples.Mon, 09 Feb 2026 00:00:00 GMThttps://pavelhan.tech/en/article/2026-02-07-the-machine-learning-python-web-UI-framework-gradio/https://pavelhan.tech/en/article/2026-02-07-the-machine-learning-python-web-UI-framework-gradio/Gradio is currently one of the most popular and user-friendly Python Web UI frameworks in the fields of machine learning and data science. Simply put, its core mission is to let you build a visual demo interface for your machine learning model instantly with a very short amount of Python code (usually just a few lines). It is particularly ideal for rapid prototyping, showcasing model performance to teams/clients, or hosting demos on Hugging Face Spaces.Sat, 07 Feb 2026 00:00:00 GMThttps://pavelhan.tech/en/article/2026-02-04-the-opensource-dataset-managememt-tool-fiftyone/https://pavelhan.tech/en/article/2026-02-04-the-opensource-dataset-managememt-tool-fiftyone/This article summarizes the working features, environment setup, and common application scenarios of FiftyOne, an open-source dataset visualization and management engine developed by Voxel51.Wed, 04 Feb 2026 00:00:00 GMThttps://pavelhan.tech/en/article/2026-02-03-the-light-weighted-multi-modal-CLIP/https://pavelhan.tech/en/article/2026-02-03-the-light-weighted-multi-modal-CLIP/Released by OpenAI in early 2021, CLIP (Contrastive Language-Image Pre-Training) is a pre-trained neural network model designed to match images and text, representing a classic milestone in recent multi-modal research.Tue, 03 Feb 2026 00:00:00 GMThttps://pavelhan.tech/en/article/2026-02-01-the-opensource-VLM-modal-Moondream/https://pavelhan.tech/en/article/2026-02-01-the-opensource-VLM-modal-Moondream/This article provides a detailed introduction to MoonDream, a very popular open-source lightweight Vision-Language Model in the industry, summarizing its core feature list, basic testing workflow, and licensing details.Sun, 01 Feb 2026 00:00:00 GMThttps://pavelhan.tech/en/article/2025-11-25-the-detailed-explanation-of-YOLO-configuration-file/https://pavelhan.tech/en/article/2025-11-25-the-detailed-explanation-of-YOLO-configuration-file/This article provides a detailed summary and explanation of all parameters contained in the default.yaml configuration file of the ultralytics/YOLO project (excluding visualization and export parameters).Tue, 25 Nov 2025 00:00:00 GMThttps://pavelhan.tech/en/article/2025-11-20-the-network-structure-of-YOLOv8-model/https://pavelhan.tech/en/article/2025-11-20-the-network-structure-of-YOLOv8-model/This article details and summarizes the similarities and differences in network architecture design between the YOLOv8 and YOLOv5 models, providing a comprehensive and in-depth understanding of the YOLOv8 structure.Thu, 20 Nov 2025 00:00:00 GMThttps://pavelhan.tech/en/article/2025-11-15-the-explanation-of-pytorch-calculation-graph/https://pavelhan.tech/en/article/2025-11-15-the-explanation-of-pytorch-calculation-graph/Based on the study of PyTorch's fundamental data structure torch.Tensor, this article organizes the theory behind torch's gradient and automatic differentiation features, and uses examples to clearly illustrate the runtime logic of computation graphs and the training workflow within the PyTorch framework.Sat, 15 Nov 2025 00:00:00 GMThttps://pavelhan.tech/en/article/2025-11-11-the-predict-output-of-YOLOv5-and-its-NMS-workflow/https://pavelhan.tech/en/article/2025-11-11-the-predict-output-of-YOLOv5-and-its-NMS-workflow/This article summarizes the data structure output by the YOLOv5 detection head after forward inference on input image data, as well as the Non-Maximum Suppression (NMS) algorithm workflow executed on these outputs.Tue, 11 Nov 2025 00:00:00 GMThttps://pavelhan.tech/en/article/2025-11-05-the-evaluation-metrics-of-computer-vision-model-P-R-PR-F1/https://pavelhan.tech/en/article/2025-11-05-the-evaluation-metrics-of-computer-vision-model-P-R-PR-F1/The four image files F1_curve, P_curve, PR_curve, and R_curve generated in the YOLOv5 model training results correspond to the F1, P, PR, and R metric curves after model training completion, respectively. This article provides a detailed summary and organization of these four metrics.Fri, 07 Nov 2025 00:00:00 GMThttps://pavelhan.tech/en/article/2025-11-07-the-explanation-of-YOLO-training-output-file/https://pavelhan.tech/en/article/2025-11-07-the-explanation-of-YOLO-training-output-file/This article interprets the files generated during the YOLO model training process on a custom dataset, helping to build a deeper understanding of the YOLO training workflow.Fri, 07 Nov 2025 00:00:00 GMThttps://pavelhan.tech/en/article/2025-11-05-the-summary-of-YOLOv5-code-detect-py/https://pavelhan.tech/en/article/2025-11-05-the-summary-of-YOLOv5-code-detect-py/This article provides a detailed analysis of the source code of the detect.py script used to execute inference tasks in YOLOv5. It offers a comprehensive understanding of the entire process, from parameter passing and parsing to inference execution and result output. The detect.py script in YOLOv5 is specifically designed to perform inference tasks after a model has been trained. That is, it uses the trained model to predict new images, videos, or real-time streams, identify and label objects of interest, and store the results.Wed, 05 Nov 2025 00:00:00 GMThttps://pavelhan.tech/en/article/2025-11-01-the-installation-process-of-CUDA-pytorch-developmemnt-environment/https://pavelhan.tech/en/article/2025-11-01-the-installation-process-of-CUDA-pytorch-developmemnt-environment/This article documents the setup and verification of a Cuda + PyTorch development environment on Windows 11 with an Nvidia RTX 5070 Ti GPU.Sat, 01 Nov 2025 00:00:00 GMThttps://pavelhan.tech/en/article/2025-10-30-the-summary-of-YOLOv5-config-file/https://pavelhan.tech/en/article/2025-10-30-the-summary-of-YOLOv5-config-file/Combined with the architecture diagram of the YOLOv5 model, this article provides a detailed summary and explanation of the configuration parameter details for each section of the model's yaml configuration file, helping to gain a more granular understanding of the differences between various scale versions of the model.Thu, 30 Oct 2025 00:00:00 GMThttps://pavelhan.tech/en/article/2025-10-26-the-summary-of-YOLOv5-model/https://pavelhan.tech/en/article/2025-10-26-the-summary-of-YOLOv5-model/Based on the P3 version of YOLOv5, this article provides a detailed summary of its overall network architecture and the working logic of each sub-module, laying a solid foundation for further in-depth study of the YOLOv5 model.Sun, 26 Oct 2025 00:00:00 GMThttps://pavelhan.tech/en/article/2025-10-24-the-different-version-of-YOLOv5/https://pavelhan.tech/en/article/2025-10-24-the-different-version-of-YOLOv5/This article summarizes the different versions of the YOLOv5 model and their differences across various dimensions, including model scale, algorithmic iteration, and output structure.Fri, 24 Oct 2025 00:00:00 GMThttps://pavelhan.tech/en/article/2025-10-21-the-model-structure-of-YOLOv4/https://pavelhan.tech/en/article/2025-10-21-the-model-structure-of-YOLOv4/The first three versions of the YOLO model—v1 (June 2015), v2 (December 2016), and v3 (April 2018)—were all proposed and developed by Joseph Redmon. However, due to the inevitable application of YOLO models in the military sector, the author decided to quit the computer vision field (hats off to the author's great altruistic spirit). The new YOLOv4 version was jointly released in April 2020 by Alexey Bochkovskiy from Russia and two researchers from Taiwan, China: Hong-Yuan Mark Liao and Chien-Yao Wang.Tue, 21 Oct 2025 00:00:00 GMThttps://pavelhan.tech/en/article/2025-10-19-the-output-anchor-and-loss-function-of-YOLOv3/https://pavelhan.tech/en/article/2025-10-19-the-output-anchor-and-loss-function-of-YOLOv3/This article summarizes the YOLOv3 model, focusing on the organization format of output data, anchor prediction boxes, and the calculation of loss functions.Sun, 19 Oct 2025 00:00:00 GMThttps://pavelhan.tech/en/article/2025-10-17-the-structure-of-YOLOv3-modal/https://pavelhan.tech/en/article/2025-10-17-the-structure-of-YOLOv3-modal/This article provides a detailed summary of the overall architecture of the YOLOv3 model, including its backbone network Darknet-53, the concept of Feature Pyramid Networks (FPN), and the design principles and implementation theory of multi-scale feature map detection heads.Fri, 17 Oct 2025 00:00:00 GMThttps://pavelhan.tech/en/article/2025-10-15-YOLOv2-the-evolution-from-YOLOv1/https://pavelhan.tech/en/article/2025-10-15-YOLOv2-the-evolution-from-YOLOv1/This article provides a comprehensive summary of the features evolved in YOLOv2 based on YOLOv1, explaining the characteristics and working logic that improved various model metrics during its evolution. Built upon the design foundation of YOLOv1, YOLOv2 introduced multiple adjustments and optimizations in model design and training. Its mAP on the VOC2007 dataset increased dramatically from 63.4% to 78.6%, while retaining the one-stage design of YOLOv1 for object detection and class recognition. It maintains a very fast inference speed while being capable of recognizing more object categories.Wed, 15 Oct 2025 00:00:00 GMThttps://pavelhan.tech/en/article/2025-10-12-the-Anchor-concept-in-YOLOv2/https://pavelhan.tech/en/article/2025-10-12-the-Anchor-concept-in-YOLOv2/This article summarizes the origin, calculation, and training process of the Anchor mechanism introduced in YOLOv2—built upon Faster R-CNN's theory for model grid prediction box design—in an attempt to provide a clearer understanding of the YOLOv2 model's working principles.Sun, 12 Oct 2025 00:00:00 GMThttps://pavelhan.tech/en/article/2025-10-08-the-loss-function-and-training-flow-in-YOLOv1/https://pavelhan.tech/en/article/2025-10-08-the-loss-function-and-training-flow-in-YOLOv1/This article summarizes the training positive sample labeling method, loss function, and the complete training process of the YOLOv1 model, laying a solid foundation for understanding the processing workflows of subsequent YOLO versions.Wed, 08 Oct 2025 00:00:00 GMThttps://pavelhan.tech/en/article/2025-10-07-YOLOv1-output-and-NMS-workflow/https://pavelhan.tech/en/article/2025-10-07-YOLOv1-output-and-NMS-workflow/This article summarizes and studies the output information of the YOLOv1 model, as well as the NMS (Non-Maximum Suppression) filtering algorithm applied to the model's inference outputs, laying a solid foundation for interpreting more recent YOLO models in subsequent stages.Tue, 07 Oct 2025 00:00:00 GMThttps://pavelhan.tech/en/article/2025-10-06-YOLOv2-model-structure/https://pavelhan.tech/en/article/2025-10-06-YOLOv2-model-structure/This article provides a detailed summary and study of the YOLOv2 model's BN layer, the Darknet-19 backbone network, and its overall architecture.Mon, 06 Oct 2025 00:00:00 GMThttps://pavelhan.tech/en/article/2025-10-01-yolov1-model-structure/https://pavelhan.tech/en/article/2025-10-01-yolov1-model-structure/Although YOLOv1 is long outdated, it laid a crucial foundation for the one-stage architecture. This article provides a detailed summary of its architecture, preparing you to study subsequent versions of YOLO.Wed, 01 Oct 2025 00:00:00 GMThttps://pavelhan.tech/en/article/2025-09-30-the-classical-CNN-network-Resnet/https://pavelhan.tech/en/article/2025-09-30-the-classical-CNN-network-Resnet/The ResNet network architecture was proposed by Kaiming He and other researchers from Microsoft Research Asia in 2015 in their paper 'Deep Residual Learning for Image Recognition'. It won first place in multiple tasks such as classification, detection, and localization in the 2015 ImageNet image recognition competition. The core contribution of this model lies in...Tue, 30 Sep 2025 00:00:00 GMThttps://pavelhan.tech/en/article/2025-09-20-the-metrics-of-object-detection-modal-mAP-recall-precision/https://pavelhan.tech/en/article/2025-09-20-the-metrics-of-object-detection-modal-mAP-recall-precision/In the field of object detection in computer vision, the primary evaluation metrics are mAP, Recall, and Precision. This article provides a detailed breakdown of the concepts and calculation logic of IoU, Precision, Recall, AP, and mAP.Sat, 20 Sep 2025 00:00:00 GMThttps://pavelhan.tech/en/article/2025-09-15-the-application-note-of-SWIR-sensor/https://pavelhan.tech/en/article/2025-09-15-the-application-note-of-SWIR-sensor/This article briefly summarizes the technical concepts of SWIR sensors and imaging systems based on short-wave infrared band imaging, as well as their common applications in industry and daily life, laying a foundation for understanding and applying this technology in practical products.Mon, 15 Sep 2025 00:00:00 GMThttps://pavelhan.tech/en/article/2025-09-11-the-classical-CNN-network-GoogleNet/https://pavelhan.tech/en/article/2025-09-11-the-classical-CNN-network-GoogleNet/This article provides a comprehensive and detailed summary of the problems inherent in traditional convolutional neural networks and the design principles of the classic GoogLeNet architecture in the field of computer vision and image recognition.Thu, 11 Sep 2025 00:00:00 GMThttps://pavelhan.tech/en/article/2025-09-10-the-classical-CNN-network-NiN/https://pavelhan.tech/en/article/2025-09-10-the-classical-CNN-network-NiN/This article summarizes the design philosophy, overall architecture, and specific implementation details of NiN (Network in Network), a classic model in convolutional neural networks.Wed, 10 Sep 2025 00:00:00 GMThttps://pavelhan.tech/en/article/2025-09-09-the-classical-CNN-network-VGGNet/https://pavelhan.tech/en/article/2025-09-09-the-classical-CNN-network-VGGNet/This article provides a detailed summary of the architecture of the classic VGGNet model in the field of computer vision and image recognition, along with its implementation in PyTorch.Tue, 09 Sep 2025 00:00:00 GMThttps://pavelhan.tech/en/article/2025-09-07-the-calculation-flow-of-softmax-classification/https://pavelhan.tech/en/article/2025-09-07-the-calculation-flow-of-softmax-classification/The Softmax activation function is generally used for classifiers in multi-class classification problems. This article provides a detailed introduction and summary of the complete calculation flow for implementing neural network multi-class classifiers based on the Softmax activation function and the cross-entropy loss function. In practical AI projects, multi-class classification problems are frequently encountered. The most typical examples are the MNIST handwritten digit recognition dataset, which classifies 10 handwritten digits from 0 to 9, and the ImageNet image dataset, which classifies 1,000 everyday objects. In the field of machine learning and artificial intelligence, the Softmax classifier is the most commonly used implementation for multi-class classification.Sun, 07 Sep 2025 00:00:00 GMThttps://pavelhan.tech/en/article/2025-09-04-the-classical-CNN-network-AlexNet/https://pavelhan.tech/en/article/2025-09-04-the-classical-CNN-network-AlexNet/This article provides a detailed summary of the architecture of the classic AlexNet model in the field of computer vision and image recognition, along with its implementation in PyTorch.Thu, 04 Sep 2025 00:00:00 GMThttps://pavelhan.tech/en/article/2025-09-01-the-classical-CNN-network-Lenet/https://pavelhan.tech/en/article/2025-09-01-the-classical-CNN-network-Lenet/Using LeNet for handwritten digit recognition as an example, this article analyzes the network structure and the overall architecture of a typical Convolutional Neural Network (CNN), establishing a foundational understanding of CNNs used for image recognition and processing.Mon, 01 Sep 2025 00:00:00 GMThttps://pavelhan.tech/en/article/2025-08-28-the-training-predict-and-ONNX-export-of-YOLOv5/https://pavelhan.tech/en/article/2025-08-28-the-training-predict-and-ONNX-export-of-YOLOv5/This article provides a detailed, end-to-end summary of preprocessing user-defined training datasets and annotations into the YOLO format, followed by training, testing, and ONNX exporting of the YOLOv5 model.Thu, 28 Aug 2025 00:00:00 GMThttps://pavelhan.tech/en/article/2025-08-15-the-gamma-correction-in-ISP-processing-workflow/https://pavelhan.tech/en/article/2025-08-15-the-gamma-correction-in-ISP-processing-workflow/This article provides a detailed summary of the Gamma correction module in the image ISP processing workflow, explaining the reasons for including Gamma correction in ISP pipelines, as well as the core concepts and workflows used by mainstream ISPs for Gamma correction.Fri, 15 Aug 2025 00:00:00 GMThttps://pavelhan.tech/en/article/2025-08-14-the-summary-of-computer-vision-model/https://pavelhan.tech/en/article/2025-08-14-the-summary-of-computer-vision-model/This article summarizes the differences among the primary application directions of computer vision in the current AI field (image classification, image localization, object detection, image segmentation, semantic segmentation, instance segmentation) as well as the mainstream models existing in each application direction. Currently, image classification, object detection, and image segmentation are the three most fundamental and rapidly developing fields in computer vision.Thu, 14 Aug 2025 00:00:00 GMThttps://pavelhan.tech/en/article/2025-08-07-the-onnx-export-and-deployment-of-pytorch-model/https://pavelhan.tech/en/article/2025-08-07-the-onnx-export-and-deployment-of-pytorch-model/This article provides a detailed summary of the processes and steps for exporting models developed and trained using the PyTorch framework into universal ONNX files, and deploying them using ONNXRuntime with Python/C++ access.Thu, 07 Aug 2025 00:00:00 GMThttps://pavelhan.tech/en/article/2025-08-04-the-CNN-network-for-MNIST-dataset/https://pavelhan.tech/en/article/2025-08-04-the-CNN-network-for-MNIST-dataset/This article provides a detailed introduction and summary of the code workflow for implementing a Convolutional Neural Network (CNN) based on the PyTorch framework to recognize the MNIST handwritten digit dataset. It serves as an introductory foundation for practicing PyTorch and neural network programming.Mon, 04 Aug 2025 00:00:00 GMThttps://pavelhan.tech/en/article/2025-08-01-the-basic-summary-of-CNN-network-structure/https://pavelhan.tech/en/article/2025-08-01-the-basic-summary-of-CNN-network-structure/Based on online resources, this article provides a detailed analysis and summary of the architecture, data calculation, and transmission process of a simple Convolutional Neural Network (CNN), serving as a foundation for understanding CNN architectures.Fri, 01 Aug 2025 00:00:00 GMThttps://pavelhan.tech/en/article/2025-07-22-the-maths-basics-of-deep-learning/https://pavelhan.tech/en/article/2025-07-22-the-maths-basics-of-deep-learning/This article summarizes the mathematical foundations required to learn and understand deep learning, focusing on theories such as differentiation, partial differentiation, and composite functions, along with simple Python code demonstrations.Tue, 22 Jul 2025 00:00:00 GMThttps://pavelhan.tech/en/article/2025-07-19-the-summary-of-lost-function-in-AI-network/https://pavelhan.tech/en/article/2025-07-19-the-summary-of-lost-function-in-AI-network/This article provides a detailed study and summary of commonly used loss functions in deep learning neural networks, organizing the characteristics and applicability of various loss functions to facilitate the future understanding of architectural designs in various deep neural networks.Sat, 19 Jul 2025 00:00:00 GMThttps://pavelhan.tech/en/article/2025-07-17-the-summary-of-activation-function-in-AI-network/https://pavelhan.tech/en/article/2025-07-17-the-summary-of-activation-function-in-AI-network/This article provides a detailed study and summary of commonly used activation functions in deep learning neural networks, organizing their characteristics and applicability to facilitate the future understanding of various deep neural network architectures.Thu, 17 Jul 2025 00:00:00 GMThttps://pavelhan.tech/en/article/2025-07-15-the-summary-of-calculation-workflow-in-CNN/https://pavelhan.tech/en/article/2025-07-15-the-summary-of-calculation-workflow-in-CNN/Based on study materials, this article uses a simple convolutional neural network architecture as an example to provide a detailed summary and explanation of the complete calculation process for convolution and pooling operations in CNNs.Tue, 15 Jul 2025 00:00:00 GMThttps://pavelhan.tech/en/article/2025-05-01-the-summary-of-lens-shading-issue/https://pavelhan.tech/en/article/2025-05-01-the-summary-of-lens-shading-issue/This article provides a detailed summary of the pervasive Lens Shading issue in optical imaging, analyzing the root causes and organizing the strategies for resolving it during camera product image tuning.Thu, 01 May 2025 00:00:00 GMThttps://pavelhan.tech/en/article/2025-04-06-the-popular-audio-codec-inferface/https://pavelhan.tech/en/article/2025-04-06-the-popular-audio-codec-inferface/Based on a study and summary of the datasheet for the commonly used TLV320AIC3101 Audio Codec in the market, this article delves into the input/output interfaces of general audio codecs and their internal signal processing flows, establishing a more comprehensive understanding of audio codecs and their audio processing pipelines.Sun, 06 Apr 2025 00:00:00 GMThttps://pavelhan.tech/en/article/2025-04-02-the-Ingenic-IPC-platform-Secure-boot-workflow/https://pavelhan.tech/en/article/2025-04-02-the-Ingenic-IPC-platform-Secure-boot-workflow/This article provides a comprehensive summary and explanation of the Secure Boot function workflow used on the domestic Ingenic IPC platform.Wed, 02 Apr 2025 00:00:00 GMThttps://pavelhan.tech/en/article/2025-03-31-the-summary-of-auido-3A-AEC-ANS-AGC/https://pavelhan.tech/en/article/2025-03-31-the-summary-of-auido-3A-AEC-ANS-AGC/Summarizes the audio 3A pipeline in consumer cameras: AEC (Acoustic Echo Cancellation) echo path identification and removal, ANS (Auto Noise Suppression) noise estimation, and the dynamic adjustment flow of AGC (Auto Gain Control).Mon, 31 Mar 2025 00:00:00 GMThttps://pavelhan.tech/en/article/2025-03-28-the-wifi-protocol-of-ieee-80211kvr/https://pavelhan.tech/en/article/2025-03-28-the-wifi-protocol-of-ieee-80211kvr/This article explains the concept of wireless roaming in WiFi communications and traditional roaming workflows. It also provides a detailed summary of the three major protocols supporting the WiFi wireless roaming process—IEEE 802.11K/V/R—and elaborates on the specific problems each protocol solves.Fri, 28 Mar 2025 00:00:00 GMThttps://pavelhan.tech/en/article/2025-03-27-the-CRA-match-between-image-sensor-and-lens/https://pavelhan.tech/en/article/2025-03-27-the-CRA-match-between-image-sensor-and-lens/CRA stands for Chief Ray Angle. While both lenses and image sensors have CRA parameters, their actual definitions are notably different. The CRA of a lens is determined by its optical design, representing the angle distribution pattern of light rays from the lens center to the image plane.Thu, 27 Mar 2025 00:00:00 GMThttps://pavelhan.tech/en/article/2025-03-20-the-secure-boot-workflow-of-novatek-IPC/https://pavelhan.tech/en/article/2025-03-20-the-secure-boot-workflow-of-novatek-IPC/Based on the study of materials related to the Novatek NT98567, this article outlines the complete process of encryption, decryption, and protection across various boot stages in the platform's Secure Boot workflow, providing an excellent practical case study for deeply understanding the concepts and procedures of Secure Boot in embedded systems.Thu, 20 Mar 2025 00:00:00 GMThttps://pavelhan.tech/en/article/2025-03-19-the-application-level-of-LLM/https://pavelhan.tech/en/article/2025-03-19-the-application-level-of-LLM/This series of articles aims to help non-AI professionals understand the basic concepts of AI and its large language models (LLMs) in practical applications. By deeply understanding and clarifying these concepts, we aim to build a knowledge structure regarding the working mechanisms, workflows, and application frameworks of LLMs, enabling us to better utilize AI in our daily lives and work.Wed, 19 Mar 2025 00:00:00 GMThttps://pavelhan.tech/en/article/2025-03-18-the-AI-agent-framework-and-workflow/https://pavelhan.tech/en/article/2025-03-18-the-AI-agent-framework-and-workflow/The goal of this article series is to help non-AI professionals understand the basic concepts of AI and Large Language Models (LLMs) in practical applications. By deeply understanding and clarifying these concepts, we aim to build a knowledge structure regarding the working mechanisms, workflows, and application frameworks of LLMs, enabling us to better utilize AI in our daily lives and work.Tue, 18 Mar 2025 00:00:00 GMThttps://pavelhan.tech/en/article/2025-03-15-the-workflow-of-RAG/https://pavelhan.tech/en/article/2025-03-15-the-workflow-of-RAG/The goal of this article series is to help non-AI professionals understand the basic concepts of AI and large language models in practical applications. By deeply understanding and clarifying these concepts, we aim to build a knowledge structure regarding the working mechanisms, workflows, and application frameworks of large models, enabling us to better utilize AI in our daily lives and work.Sat, 15 Mar 2025 00:00:00 GMThttps://pavelhan.tech/en/article/2025-03-14-the-basic-development-workflow-of-LLM/https://pavelhan.tech/en/article/2025-03-14-the-basic-development-workflow-of-LLM/The goal of this series of articles is to help non-AI professionals understand the basic concepts of AI and its large language models (LLMs) in practical applications. By deeply understanding and clarifying these concepts, we aim to build a solid knowledge structure regarding the working mechanisms, workflows, and application frameworks of LLMs, enabling us to better utilize AI in our daily lives and work.Fri, 14 Mar 2025 00:00:00 GMThttps://pavelhan.tech/en/article/2025-03-13-the-basic-concepts-of-LLM-and-open-close-model/https://pavelhan.tech/en/article/2025-03-13-the-basic-concepts-of-LLM-and-open-close-model/The goal of this article series is to help non-AI professionals understand the basic concepts of AI and large language models in practical applications. By deeply understanding and clarifying these concepts, we aim to build a knowledge structure regarding the working mechanisms, workflows, and application frameworks of large models, enabling us to better utilize AI in our daily lives and work.Thu, 13 Mar 2025 00:00:00 GMThttps://pavelhan.tech/en/article/2025-03-12-the-basics-of-DNN/https://pavelhan.tech/en/article/2025-03-12-the-basics-of-DNN/The goal of this series of articles is to understand the basic concepts of AI and large models in application from the perspective of non-AI professionals. By gaining an in-depth understanding and clarification of these concepts, we aim to build a knowledge structure regarding the working mechanism, workflow, and application framework of large models, ultimately helping us better utilize AI in our daily lives and work.Wed, 12 Mar 2025 00:00:00 GMThttps://pavelhan.tech/en/article/2025-03-11-the-code-example-of-LLM-function-calling/https://pavelhan.tech/en/article/2025-03-11-the-code-example-of-LLM-function-calling/As is well known, large language models are merely text-generation tools. While possessing strong text generation and logical reasoning capabilities, they...Tue, 11 Mar 2025 00:00:00 GMThttps://pavelhan.tech/en/article/2025-03-10-What%E2%80%99s-MCP-in-LLM-modal/https://pavelhan.tech/en/article/2025-03-10-What%E2%80%99s-MCP-in-LLM-modal/MCP: Model Context Protocol, an open-source standard communication protocol released by Anthropic (the developer of Claude) in November 2024.Mon, 10 Mar 2025 00:00:00 GMThttps://pavelhan.tech/en/article/2025-03-09-the-initialization-flow-of-SD-card/https://pavelhan.tech/en/article/2025-03-09-the-initialization-flow-of-SD-card/This article provides a comprehensive analysis and explanation of the complete initialization flow between the SD host controller and the SD card after insertion. For a consumer electronic product supporting SD cards, this covers the communication sequence between the SD host and the card once inserted into the slot, and how this initialization process prepares the system for further read and write operations.Sun, 09 Mar 2025 00:00:00 GMThttps://pavelhan.tech/en/article/2025-03-06-the-CMD6-command-of-SD-card/https://pavelhan.tech/en/article/2025-03-06-the-CMD6-command-of-SD-card/In the SD protocol, CMD6 is a relatively complex command within the interaction process between the SD host and the SD card. Its complexity is reflected in: - The same command can be used to either read the features supported by the SD card or configure them. - The execution of the CMD6 command and its response message read from the SD card involve communication not only on the SD CMD pin, but also data transmission on the DAT pins, whereas the execution of most other CMD commands involves only the CMD pin. - CMD6 supports a wide range of functions, including multiple function groups, with each function group containing multiple function modes. Therefore, based on an in-depth study of the SD Physical Layer Simplified Specification (Version 6.00), this article provides a detailed compilation of the CMD6 command interaction workflow.Thu, 06 Mar 2025 00:00:00 GMThttps://pavelhan.tech/en/article/2025-03-04-the-difference-of-SD-SDIO-EMMC/https://pavelhan.tech/en/article/2025-03-04-the-difference-of-SD-SDIO-EMMC/SDIO (Secure Digital Input Output) and SD cards (Secure Digital Memory Card) both belong to the SD (Secure Digital) standard system, but their design goals and functional implementations have distinct differences: an SD card is a dedicated storage device, whereas SDIO provides a high-speed expansion interface for general-purpose peripherals using the same SD interface and a similar SD protocol framework. Simply put, SDIO and SD cards are fully compatible at the hardware physical layer, but they have developed their own independent systems for specific communication protocols.Tue, 04 Mar 2025 00:00:00 GMThttps://pavelhan.tech/en/article/2025-03-02-the-summary-of-SD-command/https://pavelhan.tech/en/article/2025-03-02-the-summary-of-SD-command/As is well known, there is a dedicated CMD pin on the SD interface between an SD card and its controller. Working in conjunction with the CLK pin, the CMD pin handles the transmission of control and configuration commands between the SD card and its host controller. During each command-mode communication, the SD host sends a CMD command structure to the card via the CMD pin, and the SD card returns a corresponding response message Rx based on the specific CMD command.Sun, 02 Mar 2025 00:00:00 GMThttps://pavelhan.tech/en/article/2025-03-01-the-LLM-image-recognition-using-HTTP-API/https://pavelhan.tech/en/article/2025-03-01-the-LLM-image-recognition-using-HTTP-API/Building upon the previous notes, this article continues to utilize OpenAI's API to access Kimi's multimodal model for object recognition in images, implemented using both Python and C with detailed case analyses. By using C to access the HTTP API interfaces exposed by multimodal large language models, developers can implement features requiring large model service support on low-cost MCU processors, backed by reasonable prompt engineering.Sat, 01 Mar 2025 00:00:00 GMThttps://pavelhan.tech/en/article/2025-02-27-the-communication-with-Moonshot-LLM-using-python/https://pavelhan.tech/en/article/2025-02-27-the-communication-with-Moonshot-LLM-using-python/For AI application development based on Large Language Models (LLMs), user applications and LLMs like Kimi or OpenAI essentially communicate using standard HTTP requests. The Kimi and OpenAI servers respond to questions posed by user applications, and the results are similarly encapsulated in HTTP response messages and sent back to the client. The application then parses the result to present it to the user or passes it to more intelligent processing functions (such as an AI Agent). Here, we choose the domestic LLM developer Moonshot AI (specifically Kimi) as an example to learn and summarize the interaction logic between AI applications and the LLM Server. The reasons for using Kimi include: - Before Deepseek, Kimi had been my consistently used AI tool. Its stability and output quality have always been top-tier compared to other domestic large models. - Moonshot provides a pre-recharge amount of 15 RMB for each registered user, which is generally sufficient for testing and development via API. For developing Moonshot-based AI applications, the preliminary preparations mainly include two parts: - Installing Python and its OpenAI library according to Moonshot's requirements. - Applying for an API Key to access the Moonshot server and configuring it as an environment variable on your development machine for security purposes.Thu, 27 Feb 2025 00:00:00 GMThttps://pavelhan.tech/en/article/2025-02-21-the-summary-of-SDcard-catalogue-and-parameters/https://pavelhan.tech/en/article/2025-02-21-the-summary-of-SDcard-catalogue-and-parameters/Size types - SD: 32×24×2.1mm (full size), basically rarely used anymore - Fri, 21 Feb 2025 00:00:00 GMThttps://pavelhan.tech/en/article/2025-02-11-the-BSS-coloring-feature-of-WiFi6/https://pavelhan.tech/en/article/2025-02-11-the-BSS-coloring-feature-of-WiFi6/In 802.11ax, also known as WiFi 6, a feature called BSS Coloring was introduced to optimize and resolve wireless interference issues among multiple Basic Service Sets (BSS) in high-density environments.Tue, 11 Feb 2025 00:00:00 GMThttps://pavelhan.tech/en/article/2025-02-05-the-OFDMA-feature-of-WiFi6/https://pavelhan.tech/en/article/2025-02-05-the-OFDMA-feature-of-WiFi6/OFDMA: Short for Orthogonal Frequency Division Multiple Access. In Wi-Fi 4, Wi-Fi 5, and even the earlier 802.11a protocols predating Wi-Fi 6, the OFDM mechanism was already adopted. This involves dividing the bandwidth of the entire communication channel into multiple overlapping yet orthogonal subcarriers to maximize data transmission rates and spectrum utilization, while overcoming multipath interference issues in wireless transmissions. However, when using OFDM alone, each communication session between the Wi-Fi AP and STA is intended for a single user. This means that whenever data is transmitted, regardless of the user's data volume, the communication with that user occupies all subcarriers. If we metaphorically view all subcarriers of the entire channel as a delivery cart, when a user needs to transmit a very small amount of data (such as instant messages or web browsing), the data volume cannot fully utilize all subcarriers, leaving the cart underfilled. Yet, according to OFDM's working mechanism and flow, this underfilled cart can only contain data for that single user, and the remaining space in the cart (i.e., the leftover idle subcarriers) is simply wasted.Wed, 05 Feb 2025 00:00:00 GMThttps://pavelhan.tech/en/article/2025-02-01-the-structure-of-wifi6-trigger-frame/https://pavelhan.tech/en/article/2025-02-01-the-structure-of-wifi6-trigger-frame/The implementation of OFDMA (Orthogonal Frequency Division Multiple Access) in WiFi 6 (802.11ax) relies on a critical mechanism called the Trigger Frame (TF). This article provides an in-depth technical analysis of the detailed structure of the Trigger Frame.Sat, 01 Feb 2025 00:00:00 GMThttps://pavelhan.tech/en/article/2025-01-25-AI-NVR-and-Ingenic-A1-solution/https://pavelhan.tech/en/article/2025-01-25-AI-NVR-and-Ingenic-A1-solution/Ingenic's A1 series is an integrated solution tailored for the NVR market. Compared to traditional NVR solutions, its standout feature is the integration of robust AI computing power. Therefore, Ingenic deliberately named this solution using the xVR format to emphasize its AI capabilities.Sat, 25 Jan 2025 00:00:00 GMThttps://pavelhan.tech/en/article/2025-01-20-the-study-of-RF-components/https://pavelhan.tech/en/article/2025-01-20-the-study-of-RF-components/This note provides a brief summary of the basic working principles and applications of various common component circuits in wireless radio frequency (RF) circuits, laying a solid foundation for understanding and designing complete RF circuit system architectures in the future.Mon, 20 Jan 2025 00:00:00 GMThttps://pavelhan.tech/en/article/2025-01-17-the-comparison-of-duplexer-and-diplexer/https://pavelhan.tech/en/article/2025-01-17-the-comparison-of-duplexer-and-diplexer/In summary: - A Diplexer is mainly used in applications where different frequency bands share a single antenna or transmission link for communication. The most typical examples are dual-band WiFi (two bands) and multiple LTE bands. - A Duplexer is primarily used within the same frequency band, utilizing different uplink and downlink communication frequency points under the FDD mode to achieve simultaneous transmit and receive full-duplex communication. The most typical application is LTE FDD communication.Fri, 17 Jan 2025 00:00:00 GMThttps://pavelhan.tech/en/article/2025-01-15-the-basics-of-dipolor-antenna/https://pavelhan.tech/en/article/2025-01-15-the-basics-of-dipolor-antenna/The half-wave dipole antenna is the most fundamental structural unit of antennas, much like molecules in chemistry.Wed, 15 Jan 2025 00:00:00 GMThttps://pavelhan.tech/en/article/2025-01-09-Gsensor-theory-and-application/https://pavelhan.tech/en/article/2025-01-09-Gsensor-theory-and-application/G-Sensor: Gravity Sensor or Accelerometer, its main function is to detect sudden changes in acceleration during object movement.Thu, 09 Jan 2025 00:00:00 GMThttps://pavelhan.tech/en/article/2025-01-04-G711-audio-encode-standard/https://pavelhan.tech/en/article/2025-01-04-G711-audio-encode-standard/G.711 is an audio compression standard defined by the ITU-T, widely used in telephone communication networks and VoIP. In practice, G.711 audio encoding/decoding is divided into two formats: u-law (mainly used in North America and Japan) and A-law (mainly used in Europe and the rest of the world), which are explained respectively in this article.Sat, 04 Jan 2025 00:00:00 GMThttps://pavelhan.tech/en/article/2025-01-03-the-wireless-communication-phase-modulation/https://pavelhan.tech/en/article/2025-01-03-the-wireless-communication-phase-modulation/Compares three basic phase modulation schemes: BPSK (0/180 degrees, 1 bit per symbol), QPSK (four phases, 2 bits per symbol) and DQPSK (differential encoding to avoid phase ambiguity), plus the high slope transition and out-of-band interference caused by poor phase switching points.Fri, 03 Jan 2025 00:00:00 GMThttps://pavelhan.tech/en/article/2024-12-27-the-principle-of-IQ-modulation-wireless-communication/https://pavelhan.tech/en/article/2024-12-27-the-principle-of-IQ-modulation-wireless-communication/This article explains in detail the widely used IQ modulation signal in wireless communication, its modulation principles and workflow, and the advantages of using it in wireless communications.Fri, 27 Dec 2024 00:00:00 GMThttps://pavelhan.tech/en/article/2024-12-26-the-antena-share-issue-on-dualband-wifi-and-BT/https://pavelhan.tech/en/article/2024-12-26-the-antena-share-issue-on-dualband-wifi-and-BT/Explains how Wi-Fi and Bluetooth share a single antenna: half-duplex TX/RX time-sharing to avoid conflicts, antenna sharing in 2.4GHz combo modules, and how dual-band Wi-Fi keeps RF performance on both 2.4GHz and 5GHz despite the wavelength difference.Thu, 26 Dec 2024 00:00:00 GMThttps://pavelhan.tech/en/article/2024-12-25-the-computation-of-wifi-datarate/https://pavelhan.tech/en/article/2024-12-25-the-computation-of-wifi-datarate/This article compiles the list of maximum supported data rates across various WiFi standards and explains how these theoretical data rates are calculated.Wed, 25 Dec 2024 00:00:00 GMThttps://pavelhan.tech/en/article/2024-12-21-the-BLE-security-mode-and-security-level/https://pavelhan.tech/en/article/2024-12-21-the-BLE-security-mode-and-security-level/This article provides a comprehensive overview of the three typical BLE security modes in practical applications and their respective security levels, with a primary focus on Security Mode 1.Sat, 21 Dec 2024 00:00:00 GMThttps://pavelhan.tech/en/article/2024-12-16-the-detailed-suammry-of-BLE-paring-process/https://pavelhan.tech/en/article/2024-12-16-the-detailed-suammry-of-BLE-paring-process/A detailed walkthrough of the BLE pairing and bonding process: the three-phase mechanism, pairing feature exchange, Association Model negotiation, LE Legacy Pairing versus LE Secure Connections, and LTK generation and distribution.Mon, 16 Dec 2024 00:00:00 GMThttps://pavelhan.tech/en/article/2024-12-16-the-summary-of-Keys-in-BLE-devices/https://pavelhan.tech/en/article/2024-12-16-the-summary-of-Keys-in-BLE-devices/Summarizes the three keys behind BLE link security: LTK (Long Term Key) for connection encryption, CSRK (Connection Signature Resolving Key) for data signing, and IRK (Identity Resolving Key) for resolving private addresses, including how each is generated and stored.Mon, 16 Dec 2024 00:00:00 GMThttps://pavelhan.tech/en/article/2024-12-13-the-suammary-of-the-feature-and-specification-of-consumer-NVR/https://pavelhan.tech/en/article/2024-12-13-the-suammary-of-the-feature-and-specification-of-consumer-NVR/Based on a study of promotional materials for mainstream consumer NVR products in the Amazon US market, this article compiles a list of features and specifications offered by mainstream products in the industry.Fri, 13 Dec 2024 00:00:00 GMThttps://pavelhan.tech/en/article/2024-12-10-the-frequency-hopping-suammery-in-BLE/https://pavelhan.tech/en/article/2024-12-10-the-frequency-hopping-suammery-in-BLE/This article provides a detailed breakdown of the BLE frequency hopping workflow, related parameters of the hopping mechanism, and the calculation logic for frequency hopping channels.Tue, 10 Dec 2024 00:00:00 GMThttps://pavelhan.tech/en/article/2024-12-07-the-unicmicro-PKE-solution-in-depth/https://pavelhan.tech/en/article/2024-12-07-the-unicmicro-PKE-solution-in-depth/This article provides a comprehensive analysis of the PKE solution provided by UnicMicro, focusing on the LF and HF communication workflows implemented at the base station and key fobs.Sat, 07 Dec 2024 00:00:00 GMThttps://pavelhan.tech/en/article/2024-12-05-the-suammray-of-MFI-software-token-authentication-server-specification/https://pavelhan.tech/en/article/2024-12-05-the-suammray-of-MFI-software-token-authentication-server-specification/This article provides an in-depth interpretation of Apple's 'Software Token Authentication Server Specification,' offering a comprehensive overview of the deployment requirements for accessory manufacturers' servers in Apple MFi certification, as well as the interaction workflow between accessory servers and Apple servers.Thu, 05 Dec 2024 00:00:00 GMThttps://pavelhan.tech/en/article/2024-12-05-the-software-token-based-certification-on-apple-MFI-assessory/https://pavelhan.tech/en/article/2024-12-05-the-software-token-based-certification-on-apple-MFI-assessory/Based on the study of MFI certification documentation, this article outlines the two types of MFI certification (Hardware Security Chip / Software Token), the MFI certification process, and the technical details regarding token authentication and management for Software Token-based MFI accessories.Tue, 03 Dec 2024 00:00:00 GMThttps://pavelhan.tech/en/article/2024-11-27-the-summary-of-nordic-nrf54l-series/https://pavelhan.tech/en/article/2024-11-27-the-summary-of-nordic-nrf54l-series/This article summarizes the specifications and parameters of the nRF54L series of Bluetooth chips officially released by Nordic in November 2024.Wed, 27 Nov 2024 00:00:00 GMThttps://pavelhan.tech/en/article/2024-11-26-the-pre-roll-bpi-solution-using-cv4003IoT/https://pavelhan.tech/en/article/2024-11-26-the-pre-roll-bpi-solution-using-cv4003IoT/This article summarizes a complete, low-cost pre-roll battery camera solution based on the CV4003IoT Image Sensor launched by Shenzhen Chuangshi Microelectronics, and compares the pros and cons of this pre-roll solution against AOV solutions.Tue, 26 Nov 2024 00:00:00 GMThttps://pavelhan.tech/en/article/2024-11-18-the-DMZ-Configuration-on-Router-and-its-limits/https://pavelhan.tech/en/article/2024-11-18-the-DMZ-Configuration-on-Router-and-its-limits/This article reviews the workflow of different types of NAT, and on this basis, summarizes the concept and working principles of DMZ, as well as the configuration and usage limitations of DMZ on standard routers.Mon, 18 Nov 2024 00:00:00 GMThttps://pavelhan.tech/en/article/2024-11-15-ARM-Trustzone-Summary/https://pavelhan.tech/en/article/2024-11-15-ARM-Trustzone-Summary/This article provides a detailed summary of the concepts behind TEE and ARM TrustZone technologies and their development history. It explains the execution flow and system architecture of TrustZone technology from two perspectives: ARM SoC hardware design and code execution flow on the CPU.Fri, 15 Nov 2024 00:00:00 GMThttps://pavelhan.tech/en/article/2024-11-05-car-key-solution-RKE-and-PKE/https://pavelhan.tech/en/article/2024-11-05-car-key-solution-RKE-and-PKE/This article provides a detailed introduction to three mainstream automotive keyless solutions—RKE, PKE, and PEPS—and attempts to address technical questions regarding the understanding of these systems.Tue, 05 Nov 2024 00:00:00 GMThttps://pavelhan.tech/en/article/2024-10-31-the-pre-roll-feature-on-ring-doorbell/https://pavelhan.tech/en/article/2024-10-31-the-pre-roll-feature-on-ring-doorbell/This article reviews the working principles of the Pre-Roll feature promoted by Ring Doorbell and OmniVision. Based on OV's OA7600 system design framework, it summarizes the complete system workflow in Pre-Roll mode, as well as a comparison of the pros and cons between AOV and Pre-Roll modes.Thu, 31 Oct 2024 00:00:00 GMThttps://pavelhan.tech/en/article/2024-10-25-the-UBI-and-UBIFS-Filesystem-On-Linux/https://pavelhan.tech/en/article/2024-10-25-the-UBI-and-UBIFS-Filesystem-On-Linux/Through two summary notes, this post provides a comprehensive overview of the core concepts, usage workflows, and storage structures of UBI and UBIFS under the Linux system, laying a solid theoretical foundation for the efficient use of the UBIFS filesystem.Fri, 25 Oct 2024 00:00:00 GMThttps://pavelhan.tech/en/article/2024-10-16-the-OOM-issue-in-Linux-Programming/https://pavelhan.tech/en/article/2024-10-16-the-OOM-issue-in-Linux-Programming/This article summarizes the OOM (Out Of Memory) errors frequently encountered by applications running under Linux systems, the handling mechanisms provided by the kernel for these errors, and considerations for applying these OOM handling methods in embedded systems.Wed, 16 Oct 2024 00:00:00 GMThttps://pavelhan.tech/en/article/2024-10-14-wifi6-low-power-TWT-summary/https://pavelhan.tech/en/article/2024-10-14-wifi6-low-power-TWT-summary/This article summarizes the workflow of TWT (Target Wake Time), a new low-power operating mode introduced in WiFi 6, compares it with the traditional Legacy Power Saving Mode, outlines the interaction processes of the three TWT modes, and shares insights on TWT in practical product applications.Mon, 14 Oct 2024 00:00:00 GMThttps://pavelhan.tech/en/article/2024-10-12-the-signal-11-sigsegv-issue-summary/https://pavelhan.tech/en/article/2024-10-12-the-signal-11-sigsegv-issue-summary/This article summarizes the causes of Signal 11 (SIGSEGV) errors frequently encountered in Linux application programming, their kernel-level handling process, and common debugging techniques used in practice.Sat, 12 Oct 2024 00:00:00 GMThttps://pavelhan.tech/en/article/2024-10-10-wechat-AV-streaming-service-in-IoT/https://pavelhan.tech/en/article/2024-10-10-wechat-AV-streaming-service-in-IoT/Based on promotional materials for Tencent's WeChat IoT and IoT Video, this article compiles information on integrating IoT Video features (focusing on WeChat's two-way audio and video calling) into IoT products, particularly IP cameras (IPCs), to serve as a reference for future product planning.Thu, 10 Oct 2024 00:00:00 GMThttps://pavelhan.tech/en/article/2024-SBOM-and-its-standard-format/https://pavelhan.tech/en/article/2024-SBOM-and-its-standard-format/This article summarizes the concept, origin, main functions, and current mainstream SBOM file formats, and provides information on the automated generation of SBOMs.Tue, 24 Sep 2024 00:00:00 GMThttps://pavelhan.tech/en/article/2024-09-13-the-APN-setting-in-LTE-register-process/https://pavelhan.tech/en/article/2024-09-13-the-APN-setting-in-LTE-register-process/This article provides a detailed summary of the concepts of APN and PLMN related to the LTE network registration process. Building upon the understanding of these two concepts, it outlines the typical network registration process for LTE modules and key precautions.Fri, 13 Sep 2024 00:00:00 GMThttps://pavelhan.tech/en/article/2024-09-11-the-comparson-of-LTECAT1-LTEM-NBIOT/https://pavelhan.tech/en/article/2024-09-11-the-comparson-of-LTECAT1-LTEM-NBIOT/This article focuses on summarizing the application characteristics of two LPWAN mobile communication technologies, LTE-M and NB-IoT, and provides a comprehensive comparison of LTE CAT 1bis, LTE-M, and NB-IoT across various dimensions.Thu, 12 Sep 2024 00:00:00 GMThttps://pavelhan.tech/en/article/2024-09-10-lte-cat1-module-summary/https://pavelhan.tech/en/article/2024-09-10-lte-cat1-module-summary/Based on online resources, this article compiles technical background information on LTE CAT 1 modules commonly used in projects, providing a brief summary of their selection pros and cons as well as working principles.Tue, 10 Sep 2024 00:00:00 GMThttps://pavelhan.tech/en/article/2024-09-04-exfat-file-system-summary/https://pavelhan.tech/en/article/2024-09-04-exfat-file-system-summary/An organization and summary of the exFAT file system structure based on online research, explaining how it internally manages data and files.Wed, 04 Sep 2024 00:00:00 GMThttps://pavelhan.tech/en/article/2024-08-30-FAT32-file-system-summary/https://pavelhan.tech/en/article/2024-08-30-FAT32-file-system-summary/This article provides a detailed analysis of the structure of the FAT32 file system, organizing some of its core concepts. On this basis, we can understand the storage structure of the entire file system as well as the logic of addition and deletion operations. This builds a more macro-level understanding of how the FAT32 file system saves data, guiding the resolution of FAT32-related issues in subsequent work.Fri, 30 Aug 2024 00:00:00 GMThttps://pavelhan.tech/en/article/2024-08-12-Secure-Boot-in-Embedded-System/https://pavelhan.tech/en/article/2024-08-12-Secure-Boot-in-Embedded-System/This document summarizes and studies the role of the Secure Boot mechanism used in embedded systems, the underlying workflow, hardware and software design principles, and the complete embedded Secure Boot process.Mon, 12 Aug 2024 00:00:00 GMThttps://pavelhan.tech/en/article/2024-08-06-Security-Chips-in-Embedded-System/https://pavelhan.tech/en/article/2024-08-06-Security-Chips-in-Embedded-System/This article summarizes anti-cloning security chips commonly used in embedded products, as well as more advanced security chips used for encrypted communication and authentication. Using the widely adopted ATECC608 security chip as an example, this post outlines the application logic and general workflow of this security chip solution in embedded MCU and Linux systems based on web research.Tue, 06 Aug 2024 00:00:00 GMThttps://pavelhan.tech/en/article/2024-07-29-matter-device-types-list-and-status/https://pavelhan.tech/en/article/2024-07-29-matter-device-types-list-and-status/Based on a study of the latest Matter 1.3 specification document, this article organizes the device types supported in the newest Matter ecosystem protocol, as well as the current status of support for these device types among platforms and device developers.Mon, 29 Jul 2024 00:00:00 GMThttps://pavelhan.tech/en/article/2024-07-27-Embedded-Software-Development-with-Scrum-and-CI/https://pavelhan.tech/en/article/2024-07-27-Embedded-Software-Development-with-Scrum-and-CI/Based on my takeaways from reading 'Continuous Delivery 2.0' and insights gained from discussions with clients, this article outlines several approaches to applying software engineering concepts like Agile and Continuous Integration (CI) to the embedded software domain.Sat, 27 Jul 2024 00:00:00 GMThttps://pavelhan.tech/en/article/2024-07-23-matter-beginner-guide/https://pavelhan.tech/en/article/2024-07-23-matter-beginner-guide/This article studies and summarizes Matter, the universal standard protocol for the smart home ecosystem, helping you build a preliminary and comprehensive understanding of Matter.Tue, 23 Jul 2024 00:00:00 GMThttps://pavelhan.tech/en/article/2024-07-16-RGBIR-sensor-workflow-summary/https://pavelhan.tech/en/article/2024-07-16-RGBIR-sensor-workflow-summary/This article compares the differences between Bayer RGB image sensors commonly used in the IPC field and RGB-IR image sensors. Based on the components of the RGB-IR sensor image processing system and several typical RGB-IR image applications, it provides a preliminary summary of the technical working principles and applications of RGB-IR image sensors.Tue, 16 Jul 2024 00:00:00 GMThttps://pavelhan.tech/en/article/2024-07-15-homekit-secure-camera-study-summary/https://pavelhan.tech/en/article/2024-07-15-homekit-secure-camera-study-summary/Based on research into public data regarding Apple's HomeKit smart home ecosystem, this article summarizes the technical background of HomeKit's usage and implementation, focusing on the HomeKit Secure Video service provided for smart home cameras and its technical implementation principles.Mon, 15 Jul 2024 00:00:00 GMThttps://pavelhan.tech/en/article/2024-06-21-BIOS-UEFI-MBR-GPTGRUB-EFI-Basics/https://pavelhan.tech/en/article/2024-06-21-BIOS-UEFI-MBR-GPTGRUB-EFI-Basics/This article summarizes basic concepts related to the PC operating system boot process, providing a comprehensive understanding of PC booting, partition schemes, and multi-OS dual-boot technologies.Fri, 21 Jun 2024 00:00:00 GMThttps://pavelhan.tech/en/article/2024-06-07-wifi-wpa2-4way-handshake-details/https://pavelhan.tech/en/article/2024-06-07-wifi-wpa2-4way-handshake-details/This article provides a detailed summary of the key structure, authentication, and key exchange processes in the WiFi WPA/WPA2 authentication mode, focusing on the 4-way handshake mechanism.Fri, 07 Jun 2024 00:00:00 GMThttps://pavelhan.tech/en/article/2024-06-01-8021x-radius-basics/https://pavelhan.tech/en/article/2024-06-01-8021x-radius-basics/This article summarizes some basic knowledge of adding 802.1X RADIUS authentication to Wi-Fi access, serving as an introductory primer on the subject.Sat, 01 Jun 2024 00:00:00 GMThttps://pavelhan.tech/en/article/2024-05-25-apple-find-my-unwanted-tracking-alert/https://pavelhan.tech/en/article/2024-05-25-apple-find-my-unwanted-tracking-alert/This article summarizes the four operating states of Apple Find My Accessories and focuses on the implementation process of Apple's Unwanted Tracking Alert mechanism designed for the Separated state. This mechanism issues alerts when users might be tracked, preventing risks associated with location privacy leaks.Sat, 25 May 2024 00:00:00 GMThttps://pavelhan.tech/en/article/2022-08-23-most-popular-wireless-cast-techonology/https://pavelhan.tech/en/article/2022-08-23-most-popular-wireless-cast-techonology/This article compares the main workflows and features of mainstream wireless casting technologies currently available on the market, based on a compilation of relevant online resources.Tue, 23 Aug 2022 00:00:00 GMThttps://pavelhan.tech/en/article/2022-07-12-svn-standard-workflow/https://pavelhan.tech/en/article/2022-07-12-svn-standard-workflow/Based on reflections on the code management workflows of development teams in my work and a study of relevant online resources, this article provides a complete and re-summarized workflow for using SVN for unified code management in a team.Tue, 12 Jul 2022 00:00:00 GMThttps://pavelhan.tech/en/article/2022-06-21-sigmastar-uboot-ufu-firmware-upgrade-mode/https://pavelhan.tech/en/article/2022-06-21-sigmastar-uboot-ufu-firmware-upgrade-mode/This article summarizes the UFU mode added to Uboot by SigmaStar, which allows end-users to perform secure firmware upgrades via a USB connection in Uboot under this scheme.Tue, 21 Jun 2022 00:00:00 GMThttps://pavelhan.tech/en/article/2022-05-31-ucconfig-mode-0-summary/https://pavelhan.tech/en/article/2022-05-31-ucconfig-mode-0-summary/Based on the UCConfig specification document and Teams certification requirements for H.264 encoders, this article summarizes the H.264 encoding structure and bitstream structure of UCConfig Mode 0.Tue, 31 May 2022 00:00:00 GMThttps://pavelhan.tech/en/article/2022-05-30-cmos-image-sensor-exposure-readout-timing/https://pavelhan.tech/en/article/2022-05-30-cmos-image-sensor-exposure-readout-timing/A summary of CMOS Image Sensor exposure and readout timing, compiled and structured based on online resources and research.Mon, 30 May 2022 00:00:00 GMThttps://pavelhan.tech/en/article/2022-05-27-ucconfig-mode-1-summary/https://pavelhan.tech/en/article/2022-05-27-ucconfig-mode-1-summary/Based on studying the UCConfig specification and the Teams certification specification for H.264 Encoders, this article summarizes the H.264 encoding structure and bitstream structure of UCConfig Mode 1.Fri, 27 May 2022 00:00:00 GMThttps://pavelhan.tech/en/article/2022-05-20-MS-skype-for-business-h264-video-encoder-specification/https://pavelhan.tech/en/article/2022-05-20-MS-skype-for-business-h264-video-encoder-specification/Based on the official Microsoft Teams certification document "Microsoft Skype for Business H.264 Video Encoder Specification", this article outlines the technical requirements and workflows for Teams H.264 Encoder certification.Fri, 20 May 2022 00:00:00 GMThttps://pavelhan.tech/en/article/2022-05-13-H264-basics-svc/https://pavelhan.tech/en/article/2022-05-13-H264-basics-svc/Based on a study of reference materials, this article summarizes some basic information regarding the SVC extension of H.264.Fri, 13 May 2022 00:00:00 GMThttps://pavelhan.tech/en/article/2022-05-06-mipi-csi-long-short-packet-struct-and-virtual-channel/https://pavelhan.tech/en/article/2022-05-06-mipi-csi-long-short-packet-struct-and-virtual-channel/Based on a study of reference documents, this article summarizes the data structures of long and short packets commonly used in image sensor MIPI CSI interface transmissions, as well as the concept of virtual channels.Fri, 06 May 2022 00:00:00 GMThttps://pavelhan.tech/en/article/2022-04-29-image-sensor-mipi-csi-interface/https://pavelhan.tech/en/article/2022-04-29-image-sensor-mipi-csi-interface/This post summarizes the basics of image data transmission using the MIPI CSI interface commonly used in Image Sensors, covering both hardware connections and software levels.Fri, 29 Apr 2022 00:00:00 GMThttps://pavelhan.tech/en/article/2022-04-26-cmos-image-sensor-flicker/https://pavelhan.tech/en/article/2022-04-26-cmos-image-sensor-flicker/This article summarizes the causes and solutions for common sensor flicker issues in CMOS image sensors.Tue, 26 Apr 2022 00:00:00 GMThttps://pavelhan.tech/en/article/2022-04-26-sony-dol-hdr-basics/https://pavelhan.tech/en/article/2022-04-26-sony-dol-hdr-basics/A summary of the working principles and workflow of Sony's DOL HDR technology, compiled from online reference materials and documentation.Tue, 26 Apr 2022 00:00:00 GMThttps://pavelhan.tech/en/article/2022-04-19-WSDL-basics/https://pavelhan.tech/en/article/2022-04-19-WSDL-basics/A summary of WSDL study notes compiled from various online resources, laying the groundwork for subsequent learning and development with the ONVIF protocol.Tue, 19 Apr 2022 00:00:00 GMThttps://pavelhan.tech/en/article/2022-04-13-SOAP-baics/https://pavelhan.tech/en/article/2022-04-13-SOAP-baics/This article compiles basic study notes on SOAP (Simple Object Access Protocol) based on online reference materials, laying the foundation for ONVIF development.Wed, 13 Apr 2022 00:00:00 GMThttps://pavelhan.tech/en/article/2022-03-30-nuvoton-isd9160-audio-recognition-solution/https://pavelhan.tech/en/article/2022-03-30-nuvoton-isd9160-audio-recognition-solution/Based on Nuvoton's ISD9160 datasheet, voice recognition development documentation, and video tutorials, this article summarizes the general workflow for developing local voice recognition products using the ISD9160.Wed, 30 Mar 2022 00:00:00 GMThttps://pavelhan.tech/en/article/2022-03-24-linux-uac-gadget-audio-control-kernel-get/https://pavelhan.tech/en/article/2022-03-24-linux-uac-gadget-audio-control-kernel-get/This article summarizes the complete workflow provided by SigmaStar for adding audio control functionality to a Linux kernel-based UAC gadget device, focusing on the kernel-level GET part.Thu, 24 Mar 2022 00:00:00 GMThttps://pavelhan.tech/en/article/2022-03-24-linux-uac-gadget-audio-control-kernel-set/https://pavelhan.tech/en/article/2022-03-24-linux-uac-gadget-audio-control-kernel-set/This article summarizes the complete workflow provided by SigmaStar for adding audio control functionality to UAC gadget devices based on the Linux kernel, specifically focusing on the kernel-layer SET portion.Thu, 24 Mar 2022 00:00:00 GMThttps://pavelhan.tech/en/article/2022-03-23-linux-uac-gadget-audio-control-application/https://pavelhan.tech/en/article/2022-03-23-linux-uac-gadget-audio-control-application/This article summarizes the complete workflow provided by SigmaStar for adding audio control functionality to Linux kernel-based UAC gadget devices, focusing on the application layer.Wed, 23 Mar 2022 00:00:00 GMThttps://pavelhan.tech/en/article/2022-03-18-usb-interface-endpoint-summary/https://pavelhan.tech/en/article/2022-03-18-usb-interface-endpoint-summary/Based on learnings from 'USB in a Nutshell', this article summarizes key concepts regarding interfaces and endpoints in the standard USB protocol.Fri, 18 Mar 2022 00:00:00 GMThttps://pavelhan.tech/en/article/2022-03-16-h264-slice-nalu/https://pavelhan.tech/en/article/2022-03-16-h264-slice-nalu/This article summarizes concepts such as Slice and NALU in H.264 video encoding and decoding technology.Wed, 16 Mar 2022 00:00:00 GMThttps://pavelhan.tech/en/article/2022-03-16-h264-sps-pps-sei/https://pavelhan.tech/en/article/2022-03-16-h264-sps-pps-sei/This article summarizes key concepts in H.264 video coding technology, including SPS, PPS, and SEI.Wed, 16 Mar 2022 00:00:00 GMThttps://pavelhan.tech/en/article/2022-03-11-obdii-experts-stack-summary/https://pavelhan.tech/en/article/2022-03-11-obdii-experts-stack-summary/This article is a study summary based on the official technical documentation of the OBD-II Experts Software Stack, covering the usage of this software stack and the features supported by the OBD-II protocol.Fri, 11 Mar 2022 00:00:00 GMThttps://pavelhan.tech/en/article/2022-03-10-USB-UVC-Probe-Commit-Requests/https://pavelhan.tech/en/article/2022-03-10-USB-UVC-Probe-Commit-Requests/This article provides a brief summary of the Video Streaming Probe & Commit process, which negotiates media stream formats and parameters between the Host and Device under the UVC protocol before streaming starts.Thu, 10 Mar 2022 00:00:00 GMThttps://pavelhan.tech/en/article/2022-03-03-aac-audio-profile/https://pavelhan.tech/en/article/2022-03-03-aac-audio-profile/This article summarizes the different profile types of the AAC audio codec and the process of programmatically configuring AAC profiles across various platforms.Thu, 03 Mar 2022 00:00:00 GMThttps://pavelhan.tech/en/article/2022-03-03-usb-transfer-type-interrupt-bulk-isochronous/https://pavelhan.tech/en/article/2022-03-03-usb-transfer-type-interrupt-bulk-isochronous/Based on USB in a Nutshell, this article summarizes the complete workflows of three USB transfer types: Interrupt, Bulk, and Isochronous.Thu, 03 Mar 2022 00:00:00 GMThttps://pavelhan.tech/en/article/2022-03-02-usb-uvc-get-set-request-data-structure/https://pavelhan.tech/en/article/2022-03-02-usb-uvc-get-set-request-data-structure/Based on Chapter 4 of the UVC protocol specification, this article summarizes the data structures of UVC SET and GET requests, providing detailed analysis and explanations for each field.Wed, 02 Mar 2022 00:00:00 GMThttps://pavelhan.tech/en/article/2022-03-01-usb-basic-packet/https://pavelhan.tech/en/article/2022-03-01-usb-basic-packet/Based on notes from 'USB in a Nutshell', this article summarizes the basic packet types used in USB communication.Tue, 01 Mar 2022 00:00:00 GMThttps://pavelhan.tech/en/article/2022-03-01-usb-control-transfer/https://pavelhan.tech/en/article/2022-03-01-usb-control-transfer/Based on chapters from USB in a Nutshell, this article summarizes the complete workflow of USB control transfers, illustrated with the communication process of reading a USB Device Descriptor.Tue, 01 Mar 2022 00:00:00 GMThttps://pavelhan.tech/en/article/2022-02-25-usb-setup-packet/https://pavelhan.tech/en/article/2022-02-25-usb-setup-packet/This article summarizes the structure and classification of the Setup Packet defined in the USB standard.Fri, 25 Feb 2022 00:00:00 GMThttps://pavelhan.tech/en/article/2021-05-11-bluetooth-bqb/https://pavelhan.tech/en/article/2021-05-11-bluetooth-bqb/A brief summary of Bluetooth BQB certification details.Tue, 11 May 2021 00:00:00 GMThttps://pavelhan.tech/en/article/2021-02-01-wifi-lowpower/https://pavelhan.tech/en/article/2021-02-01-wifi-lowpower/This article summarizes the Wi-Fi low-power modes, workflows, and state transitions defined in the 802.11 specification.Mon, 01 Feb 2021 00:00:00 GMThttps://pavelhan.tech/en/article/2021-01-21-wireshark-monitor/https://pavelhan.tech/en/article/2021-01-21-wireshark-monitor/This article summarizes the working principles behind wired and wireless network packet capture, as well as the basic workflow for capturing packets using Wireshark.Thu, 21 Jan 2021 00:00:00 GMThttps://pavelhan.tech/en/article/2021-01-18-wireshark-acrylic-sniffer/https://pavelhan.tech/en/article/2021-01-18-wireshark-acrylic-sniffer/This article summarizes the process of setting up a WiFi over-the-air packet capture environment using Acrylic WiFi Sniffer, Wireshark, and a compatible wireless network adapter.Mon, 18 Jan 2021 00:00:00 GMThttps://pavelhan.tech/en/article/2021-01-12-WiFi-Beacon-tim-dtim/https://pavelhan.tech/en/article/2021-01-12-WiFi-Beacon-tim-dtim/This article summarizes the Beacon frame format defined in the 802.11 protocol specification and the differences between TIM and DTIM frames.Tue, 12 Jan 2021 00:00:00 GMThttps://pavelhan.tech/en/article/2021-01-11-GPS-basics/https://pavelhan.tech/en/article/2021-01-11-GPS-basics/This article summarizes fundamental GPS knowledge and the working principles behind GPS positioning.Mon, 11 Jan 2021 00:00:00 GMThttps://pavelhan.tech/en/article/2020-10-13-gb28181-basics/https://pavelhan.tech/en/article/2020-10-13-gb28181-basics/This article provides a brief summary of the GB28181 standard, development workflow, and architecture for domestic audio and video surveillance systems in China.Tue, 13 Oct 2020 00:00:00 GMThttps://pavelhan.tech/en/article/2020-09-29-QT-ffmpeg-example/https://pavelhan.tech/en/article/2020-09-29-QT-ffmpeg-example/This article summarizes a simple example of developing a player using QT and ffmpeg.Tue, 29 Sep 2020 00:00:00 GMThttps://pavelhan.tech/en/article/2020-09-24-qt-creator-ffmpeg/https://pavelhan.tech/en/article/2020-09-24-qt-creator-ffmpeg/A summary of setting up an FFmpeg development environment with QT Creator in a Windows environment, including test code.Thu, 24 Sep 2020 00:00:00 GMThttps://pavelhan.tech/en/article/2020-09-22-AHD-coaxial-protocol/https://pavelhan.tech/en/article/2020-09-22-AHD-coaxial-protocol/This article summarizes the Coaxial protocol used for reverse control of PTZ and other devices on AHD cameras via coaxial cable.Tue, 22 Sep 2020 00:00:00 GMThttps://pavelhan.tech/en/article/2020-09-15-hi3521-QT-porting/https://pavelhan.tech/en/article/2020-09-15-hi3521-QT-porting/This article summarizes the complete process of porting QT5.9.8 to the HiSilicon 3521 platform. Once ported, QT application development can be performed on the 3521 platform.Tue, 15 Sep 2020 00:00:00 GMThttps://pavelhan.tech/en/article/2020-08-07-AF-PDAF/https://pavelhan.tech/en/article/2020-08-07-AF-PDAF/This article summarizes the classification of AF autofocus algorithms and provides an overview of two passive focusing technologies: contrast-based and PDAF.Fri, 07 Aug 2020 00:00:00 GMThttps://pavelhan.tech/en/article/2020-07-31-AF-lens-basics/https://pavelhan.tech/en/article/2020-07-31-AF-lens-basics/This article briefly summarizes the differences between digital zoom and optical zoom, and their specific technical implementation principles.Fri, 31 Jul 2020 00:00:00 GMThttps://pavelhan.tech/en/article/2020-07-24-usb-uvc-descriptor/https://pavelhan.tech/en/article/2020-07-24-usb-uvc-descriptor/This article briefly summarizes the structure of USB descriptors for USB Composite devices, especially UVC Camera devices.Fri, 24 Jul 2020 00:00:00 GMThttps://pavelhan.tech/en/article/2020-07-07-Linux-LUKS/https://pavelhan.tech/en/article/2020-07-07-Linux-LUKS/This article summarizes the complete process of implementing disk encryption on Linux using LUKS technology. Accessing the encrypted disk requires entering the key specified during creation.Tue, 07 Jul 2020 00:00:00 GMThttps://pavelhan.tech/en/article/2020-06-22-TI-guage-impedance-track/https://pavelhan.tech/en/article/2020-06-22-TI-guage-impedance-track/This article summarizes the fundamental knowledge of TI's Impedance Track technology used in TI fuel gauges, based on the study of relevant TI documentation.Mon, 22 Jun 2020 00:00:00 GMThttps://pavelhan.tech/en/article/2020-06-19-debian-jenkins-c_c++/https://pavelhan.tech/en/article/2020-06-19-debian-jenkins-c_c++/This article describes the process of setting up a C/C++ continuous integration environment based on Jenkins in a Debian environment.Fri, 19 Jun 2020 00:00:00 GMThttps://pavelhan.tech/en/article/2020-06-10-00-li-battery-basics/https://pavelhan.tech/en/article/2020-06-10-00-li-battery-basics/A summary of lithium battery technology, aimed at addressing a lack of understanding regarding battery charge/discharge characteristics during battery product development.Wed, 10 Jun 2020 00:00:00 GMThttps://pavelhan.tech/en/article/2020-06-03-linux-ipc-message-queue/https://pavelhan.tech/en/article/2020-06-03-linux-ipc-message-queue/This article summarizes the conceptual knowledge of message queues, one of the IPC mechanisms provided by the Linux application layer, and provides examples of application layer programming using message queues.Wed, 03 Jun 2020 00:00:00 GMThttps://pavelhan.tech/en/article/2020-06-01-debian-linux-cppcheck/https://pavelhan.tech/en/article/2020-06-01-debian-linux-cppcheck/This article summarizes the process of using the cppcheck tool for static analysis of C code on Linux.Mon, 01 Jun 2020 00:00:00 GMThttps://pavelhan.tech/en/article/2020-05-26-hisilicon-35xx-himpp-framework-vi/https://pavelhan.tech/en/article/2020-05-26-hisilicon-35xx-himpp-framework-vi/This article summarizes some basic knowledge of VI module development under the Hisilicon 35XX HiMPP framework, based on the study of relevant documentation for Hisilicon 35XX processors.Tue, 26 May 2020 00:00:00 GMThttps://pavelhan.tech/en/article/2020-05-22-GPS-NMEA-td3030c/https://pavelhan.tech/en/article/2020-05-22-GPS-NMEA-td3030c/This article summarizes the protocol parsing of the standard GPS NMEA data format and introduces the TD3020C GPS module.Fri, 22 May 2020 00:00:00 GMThttps://pavelhan.tech/en/article/2020-05-18-bt601-bt656-bt1120-basics/https://pavelhan.tech/en/article/2020-05-18-bt601-bt656-bt1120-basics/This article summarizes the fundamental knowledge related to BT.601, BT.656, BT.1120, and other standards concerning video transmission in both analog and digital domains.Mon, 18 May 2020 00:00:00 GMThttps://pavelhan.tech/en/article/2020-05-14-analog-HD/https://pavelhan.tech/en/article/2020-05-14-analog-HD/This article provides a brief summary of the Analog HD video transmission technologies that have emerged in recent years.Thu, 14 May 2020 00:00:00 GMThttps://pavelhan.tech/en/article/2020-05-12-h264-idr-dts-pts/https://pavelhan.tech/en/article/2020-05-12-h264-idr-dts-pts/This article summarizes the concepts of IDR Frames, dts, and pts in H.264.Tue, 12 May 2020 00:00:00 GMThttps://pavelhan.tech/en/article/2020-05-10-wifi-lowpower/https://pavelhan.tech/en/article/2020-05-10-wifi-lowpower/This article summarizes the workflow of WiFi low-power modes defined in the 802.11 protocol, as well as the parsing of Beacon TIM/DTIM information.Sun, 10 May 2020 00:00:00 GMThttps://pavelhan.tech/en/article/2020-05-07-AES-encryption-algo/https://pavelhan.tech/en/article/2020-05-07-AES-encryption-algo/This article summarizes the differences between block ciphers and stream ciphers, as well as the six encryption modes for the AES encryption algorithm's execution flow.Thu, 07 May 2020 00:00:00 GMT