Support for STM32F1xx

There are STM32F103 based boards available at very affordable price-point, commonly referred to as the Bluepill as in the Matrix. The pin maps is available via STM32Duino.

SPI Mode

Using 1st bank of pins for SPI mode according to diagram here. SPI pins are in the table below |Pin function| Pin Number| |------------|-----------| |MOSI | PA7 | |MISO | PA6 | |SCK | PA5 | |CS | PA4 |

Bluepill SPI Wiring

UART Mode

NOTE - Pin functions are reversed on the ATM90E26 Side

Software Serial - TBD

Pin function (STM32) Pin Number
RX 10
TX 11

Hardware Serial - Tested Working

Pin function (STM32) Pin Number
RX PB11
TX PB10