Using STM32F103C8T6 "Blue Pill" Development Board with Arduino IDE.

I have recently bought a STM32F103C8T6 "Blue Pill" from Cytron Technologies for around $USD 3.21

The board has the following specifications:

MCU: STM32F103C8T6

Core: Single Core, Arm Cortex-M3

Operating Voltage: 3.3VDC

Max. Clock Speed: 72MHz

FLASH: 64KB

SRAM: 20KB

HSI: 8MHz

LSI: 40KHz

HSE: 8MHz

LSE: 32.768kHz

GPIO Pins – 32 with external interrupt capability

Timers – 3 16-bit Timers, 1 16-bit PWM Timer

PWM Pins – 15

Analog – 10 Channels of 12-bit ADC

I2C – 2 I2C Peripherals

USART – 3 USART Peripherals with hardware control

SPI – 2 SPI Peripherals

Other Peripherals – USB 2.0 Full Speed, CAN 2.0B

Power Sources

Any +3.3V pin (+3.3V)

Any +5V pin (+5V)

USB connector (+5V)

PCB Size: (w x l)23mm x 53mm

There is however a problem with many "Blue Pill" boards that the Resistor on the USB d+ line is a wrong value ( 4k7 or 10k where it should be 1k5 of 1k8). This error does not prevent the board from functioning, but it prevents you from uploading code with the usb port!

If you can rework a smd pcb it is easy to just replace the resistor with the correct value, but I am not quite setup for smd manufacture at the moment, and do not have smd components available anyway Maybe time to start getting into that ...

You can however use a USB to UART converter to upload code to the board. I have used Cytron's UC00C, which has a selector switch to select the uart voltage between 5v and 3v3.

My connections are as follows

UART PIN "Blue Pill" Pin

Vcc ( Red) 5v or 3v3, depending on what you selected

on the UART

Gnd (Blue) and GND Pin

TxD (Yellow) Pin A10 (Rxd)

RxD(Green) Pin A09 (TxD)

Be sure that you dont connect 5v to a 3v3 pin, as you will damage the development board !

You are now ready to program the "Blue Pill" board with the Arduino IDE

To test it, Click on File -> Examples -> A_STM32_Examples->Digital->Blink

Please change PB1 to PC13 in the code, as our builtin led is connected to pin 13 on port c ( other boards may be different )

Click on Tools->Board: and select Generic-STM32F103C Series

Click on Tools->Upload Method and Select "Serial"

Change the jumpers on the "Blue Pill" as in the photograph to enable us to upload to system memory.

Plug the usb cable into the usart and computer, the red power light will light up.

Click Tools->Port and select the port of the USB to UART converter.

Now you may click on upload and if you are lucky the led will start flashing once a second, as programmed ...

Change back the jumpers to their original position to have the board automatically run your code at startup

On Linux ( Ubuntu 18.04 ) I was not so lucky to have it work immediately, and after some additional reading and testing, found that there is some issue with the CH340 USB UART Chip and Linux CH340 Driver. I have a similar issue with ESP32 Wroom Modules..

The workaround is easy, but a bit of a pain. Press and hold down the reset button on the "Blue Pill"

Click and Hold Upload button in the IDE, Release Reset Button and Then Upload .. All should be well ...

I hope this helps someone. Please note that this may not be an issue with Windows, but i wont know as my OS of choice is Linux.

By the way, there is an Arduino bootloader available to enable you to upload software to the "Blue Pill" via the USB port. I have not been successful in getting it to work without changing that resistor yet, but will keep trying and post again when I have a solution

Update : I found a fix to allow uploading through native USB -> click Here to learn how to do that.