Hello,
We have an example I2C multimaster doing a communication between two Masters (on one board using two different instances) and a Slave (on another board) in FW STM32H5.
In terms of configuration, you don't need anything particular, just make sure the masters have different own address.
On the Masters' side, you may need to check in your error callback if there is an Acknowledge error and if it's the case DeInit and Init again your I2C to discard the error. That way, you will be able to restart your communication.
void HAL_I2C_ErrorCallback(I2C_HandleTypeDef *hi2c)
{
/** Error_Handler() function is called when error occurs.
* 1- When Slave don't acknowledge it's address, Master restarts communication.
* 2- When Master don't acknowledge the last data transferred, Slave don't care in this example.
*/
if (HAL_I2C_GetError(hi2c) != HAL_I2C_ERROR_AF)
{
/* Workaround deadlock appear due to BUS error detection Errata 64209: START badly generated after misplaced STOP */
/* Workaround deadlock appear due to BUS error detection Errata I2C-090401 : Robustness issue when receiving an
illegal void message (no SCL edges between a START and a STOP condition) */
HAL_I2C_DeInit(hi2c);
HAL_I2C_Init(hi2c);
}
}
On the Slave's side, you will have to do the same for the Bus error.
void HAL_I2C_ErrorCallback(I2C_HandleTypeDef *hi2c)
{
/** Error_Handler() function is called when error occurs.
* 1- When Slave don't acknowledge it's address, Master restarts communication.
* 2- When Master don't acknowledge the last data transferred, Slave don't care in this example.
*/
if (HAL_I2C_GetError(hi2c) == HAL_I2C_ERROR_BERR)
{
/* Workaround deadlock appear due to BUS error detection Errata 64209: START badly generated after misplaced STOP */
/* Workaround deadlock appear due to BUS error detection Errata I2C-090401 : Robustness issue when receiving an
illegal void message (no SCL edges between a START and a STOP condition) */
HAL_I2C_DeInit(hi2c);
HAL_I2C_Init(hi2c);
}
else if (HAL_I2C_GetError(hi2c) != HAL_I2C_ERROR_AF)
{
Error_Handler();
}
}
I suggest you check the examples I2C_TwoBoards_MultiMasterIT_Slave and I2C_TwoBoards_MultiMasterIT_Master in the H5 FW to have a better view of how we implemented this use case.
