The Chinese development boards are available from webshops like Ebay, AliExpress, Wish, Taobao, and many more.
You can use mysx_stm32.h from MySX-boards-library
#define MYSX_D1 PA9 // TX MYSX_D1_DFM - Digital IO (USART TX (data from MCU))
#define MYSX_D2 PA10 // RX MYSX_D2_DTM - Digital IO (USART RX (data to MCU))
#define MYSX_D3 PB1 // INT MYSX_D3_INT - Digital IO (interrupt)
#define MYSX_D4 PA8 // INT MYSX_D4_INT - Digital IO (interrupt)
#define MYSX_D5 PB6 // PWM MYSX_D5_PWM - Digital IO (PWM)
#define MYSX_D6 PB0 // MYSX_D6_PWM - Digital IO (PWM)
// I2C 2
#define MYSX_D7 PB10 //
#define MYSX_D8 PB11 //
#define MYSX_D9 PA2 // MYSX_D9_A3 - Digital IO (analog input)
#define MYSX_D10 PA3 // MYSX_D10_A4 - Digital IO (analog input)
// SPI2
#define MYSX_D11 PB15 // MYSX_D11_MOSI - Digital IO (SPI MOSI)
#define MYSX_D12 PB14 // MYSX_D12_MISO - Digital IO (SPI MISO)
#define MYSX_D13 PB13 // MYSX_D13_SCK - Digital IO (SPI SCK)
#define MYSX_D14 PB12 // MYSX_D14_CS - Digital IO (also for SPI CS)
#define MYSX_D15 PA0 // MYSX_A5 - Analog input
#define MYSX_D16 PA1 // MYSX_A6 - Analog input
//LED pins
#define MYSX_LED_ERR PB8
#define MYSX_LED_RX PB7
#define MYSX_LED_TX PB3
SPI1 for NRF24
SPI2 for W5100|W5500 module (MYSX_SPI)
I2C 2 (MYSX_I2C) SDA PB11 SCL PB10
Before begin call
Wire.setSDA(MYSX_SDA);
Wire.setSCL(MYSX_SCL);
Sketch files:
Ethernet on any SPI with STM32 Cores
MySensors Gateway with w5500 | w5100 | Serial adapter
See conponent list on GitHub