STM32F103C8 mac os zero to blink

maxgerhardt · May 2, 2023, 6:57pm

By default, Serial is the hardware UART (serial) coming out of PA9/PA10.

stm32duino/Arduino_Core_STM32/blob/565f3ecc1c2c12f9577cf648c292a5ddc5b7eb6b/variants/STM32F1xx/F103C8T_F103CB(T-U)/variant_PILL_F103Cx.h#L138-L145


      
          // Default pin used for generic 'Serial' instance
          // Mandatory for Firmata
          #ifndef PIN_SERIAL_RX
            #define PIN_SERIAL_RX         PA10
          #endif
          #ifndef PIN_SERIAL_TX
            #define PIN_SERIAL_TX         PA9
          #endif

So, the default expects you to have a USB-to-UART adapter with at least common GND connected and the adapter’s RX connected to the Bluepills PA9 pin (labeled just “A9” on the board).

Of course, you are also able to take advantage of the USB peripheral in the bluepills’s chip. It can open its own USB-CDC interface on the USB port and shows up as a regular serial port on the computer.

To do that, you must

Configure the compilation flags to enable the USB serial per Difficulty with getting USB serial [USB CDC] working - #6 by maxgerhardt
Use SerialUSB instead of Serial in your code just to be sure, per exact code above
Remove the 3.3V connection between the ST-Link and the Bluepill
Plug in the micro-usb cable into the Bluepill and your computer (it will now get its power via the USB cable with no risk of double-powering)

These configuration flags are also documented in

https://docs.platformio.org/en/latest/platforms/ststm32.html#stm32duino-configuration-system