Demo of the usage USBDevice library with Blue Pill STM32F103C8T6 board.

Dependencies:   USBDevice

STM32F103C8T6 USBSerial Demo

This project contains demo of the USB serial usage for a cheap developer board Blue Pill with STM32F103C8T6 mcu.


The USB serial port provides a good communication channel between PC and microcontroller. Especially it can be useful for a debug purposes.


  • by the specifications this board has only 64KB of the flash, but actually it can have 128KB, that will be useful for a debug builds as it requires about 100KB of the flash for this demo.
  • the board can have some problems with an USB because it has wrong value of the pull-up resistor
  • for steady reading of data from a serial port, the project contains python script (it requires PySerial and six python libraries), that is steady to the board reloading
  • the project depends on the fork of the USBDevice library. This fork contains some fixes and support of the BLUE_PILL_STM32F103C8 target.
  • the mbed-os now contains correct code for a clock initialization of the BLUE_PILL_STM32F103C8 target, so you don't need to adjust the board clocks separately


Konstantin Kochin

File content as of revision 0:24604e97c40c:

 * The example of the program for STM32F103C8T6 (Blue Pill board).
 * This program demonstrate led and usb serial port usage.
 * @author Kochin Konstantin
#include "USBSerial.h"
#include "mbed.h"
#include "stdio.h"

DigitalOut myled(LED1);
USBSerial usbSerial(0x1f00, 0x2012, 0x0001, false);

int main()
    uint32_t counter = 0;

    while (true) {
        usbSerial.printf("I am a USB serial port. Tick %d.\n", counter);

        myled = !myled;