关键词: 微控制器, 上电时序, 串口烧写, 启动配置

Abstract: In response to user feedback regarding program writing failures during the serial port upgrade process of a large water heater display control board using the CKS32F103CBT6 microcontroller, a study was conducted to analyze the causes and develop solutions. By selecting four faulty circuit boards and systematically testing and troubleshooting based on schematic diagrams and the complete upgrade process, the root cause was identified as a slow power-up sequence. This resulted in abnormal timing of the chip’s startup configuration pin (BOOT0) and reset pin (RESET), preventing the chip from entering ISP mode properly. Based on the actual circuit application scenario, the issue was successfully resolved by replacing the power module with a faster-starting one and adjusting the voltage-divider resistor and filter capacitor parameters of the BOOT0 pin. This restored normal timing for BOOT0 and RESET, effectively solving the serial port writing failure. The approach provides a feasible solution for similar timing-related upgrade failures in embedded systems.

Key words: microcontroller, power-up sequence, serial port programming, startup configuration