I have made a custom board for STM32F103 VCT6 and have shared the schematics and PCB Layouts below. I had used a blue pill dev board of STM32F103C8T6 for my circuit which worked well. However my production board (with bigger MCU) has intermittent connection problems with the computer. I configured two USB headers, one is for direct CDC configuration with the MCU(PA11 & PA12) and other through CP2102(UART2 pins) mainly used for flashing purpose. The CDC configured USB was sometimes recognized as a COM port and transfer data for a few seconds before disconnection .Sometimes the COM port does not respond to data transfer requests and causes error. Also other times the USB descriptor was not read and the USB itself was not recognized.
I have run similar codes and had no trouble running them in the blue pill board. I have triple checked all my solder joints to make sure there is no loose connections. The MCU, CP2102 and USB headers were SMT assembled by the board manufacturer. What is causing this erratic behavior of my board?
