Posted on July 17, 2017 at 18:38Your STM32F4 may have up to 3 I2C peripheral busses. I2C1, I2C2, I2C3 for example. As a naming convention, in the HAL code, they would be hi2c1, hi2c2, hi2c3. Each I2C bus can have as many slaves as your address space and pull-up resistors allow
This is how I do it, but I'm just a hobbyist not a pro.
For this discussion, let us say the I2C address is 'dev_addr'. First thing I do is make sure the device will answer
while (HAL_I2C_IsDeviceReady(&hi2c1, (uint16_t)(dev_addr<<1), 3, 100) != HAL_OK) { }
Ok then, if we get past that, we can try to read a register
HAL_StatusTypeDef status = HAL_OK;
uint8_t array[24] = {0};
status = HAL_I2C_Mem_Read_IT(&hi2c1, // i2c handle
(uint8_t)(dev_addr<<1), // i2c address, left aligned
(uint8_t)reg_addr, // register address on the slave i want to read
I2C_MEMADD_SIZE_8BIT, // random device uses 8bit register addresses. eeprom uses 16bit usually
(uint8_t*)(&array), // write returned data to this variable named array
cnt); // how many bytes to expect returned
if (status != HAL_OK)
{
switch (status)
{
case HAL_ERROR: do error stuff; break;
case HAL_BUSY: do busy stuff; break;
case HAL_TIMEOUT: do timeout stuff; break;
}
}
and dont forget to add the callback
void HAL_I2C_MemRxCpltCallback(I2C_HandleTypeDef *hi2c)
{
if (hi2c->Instance = I2C1)
{
// do stuff when the transfer on hi2c1 is complete
}
}
