stm32_bitbang_i2c

Library to implement I2C on any GPIO for STM32 MCU's. (I2C implemented in software).

Currently only tested on STM32F103, but should work on most STM32 MCU's.

Important setup

Do define your I2C pins, use STM32CubeMX. Use the following user labels:

For your SCL pin: SW_I2C_SCL

For your SDA pin: SW_I2C_SDA

The pins should be Open Drain and Pulled-up.

Example use

     #include "main.h"
     #include "stm32_sw_i2c.h"
     #include "dwt_stm32_delay.h"
     
     #define SLAVE_ADDR 0x1E
     
     uint8_t _txBuffer[6];
     uint8_t _rxBuffer[6];
     uint8_t _reg[2];

     int main(void){

              I2C_init();
              DWT_Delay_us(1000); //1 ms
              MX_GPIO_Init();
              
              //Example transmit
             _txBuffer[0] = 0x05;
             _txBuffer[1] = 0x04;
             _txBuffer[2] = 0x15;
             _txBuffer[3] = 0x00;
              I2C_transmit(SLAVE_ADDR, _txBuffer, 4); //4 is the size of the transmission (4 bytes)

             DWT_Delay_us(5000);
              //Example receive
             int reg_size = 2; //Size of reg addr to read 
             int rx_size = 4; // Number of bytes to receive
             reg[0] = 0x85;
             reg[1] = 0x20;

             for (int i = 0; i < rx_size; i++)
	            _rxBuffer[i] = 0x00; // clear rx buffer

            I2C_receive(SLAVE_ADDR, reg, _rxBuffer, reg_size, rx_size); // Stores received bytes in _rxBuffer
        
     }

Credit

This was inspired by and adapted from: https://calcium3000.wordpress.com/2016/08/19/i2c-bit-banging-tutorial-part-i/ and https://github.com/tobajer/i2cbitbang