**Problem:**
- When the I2C is enabled, the part can hit the WWDG.
- It looks like the pointer to the function `XferISR` is getting set to NULL somehow.
- When this happens, the interrupts are not cleared, and it continually fires the interrupt because it is never cleared.
- This is hard to troubleshoot because, in my system, there are many higher priority interrupts, making it hard to know that this is the problem.
- On another note, it looks like the interrupts are not always cleared in accordance with **RM0440 Table 394**:
- In the error section, I2C_FLAG_PECERR, I2C_FLAG_TIMEOUT, and I2C_FLAG_ALERT are never cleared.
- Also in I2C_Master_ISR_IT.
**Background:**
- Using an STM32G4 with HAL v1.2.3.
- Using DMA or IT (different builds).
- Connected to many I2C sensors.
- It is in a pretty noisy environment.
- All calls are from the main loop (except what was generated by HAL); all reading of buffers is in the main loop.
- If I have an I2C error, I re-init the I2C to clear out problems.
**Recommended Solutions:**
```c
void HAL_I2C_EV_IRQHandler(I2C_HandleTypeDef *hi2c) /* Derogation MISRAC2012-Rule-8.13 */
{
/* Get current IT Flags and IT sources value */
uint32_t itflags = READ_REG(hi2c->Instance->ISR);
uint32_t itsources = READ_REG(hi2c->Instance->CR1);
/* I2C events treatment -------------------------------------*/
if (hi2c->XferISR != NULL)
{
hi2c->XferISR(hi2c, itflags, itsources);
}
/* Add this */
else
{
/* if you are very confident in the HAL */
ASSERT();
/* else */
ClearAllI2cInterrupts(hi2c);
}
/* End Add */
}
```
- When there is a problem, you want to bring that to the attention of the developer to deal with it.
- I would think clearing all I2C interrupts would be more palatable.
- Also, where `XferISR = NULL`, you could set `XferISR = ClearAllI2cInterrupts;` this way, it better covers the bases.
**Questions:**
- Have you seen `XferISR` set to NULL while getting interrupts?
- Do you have any ideas why this might happen?
**Final Remarks:**
- I am going to try this out. Maybe I am smashing memory and setting `XferISR = NULL`. If after initialization it should never be NULL and then it got set to NULL, then likely I did something wrong...
