Why in some cases there is no I2C communication anymore after a system reset?

[elrhoul]

In some cases with the BMAx sensors after a system reset from host processor (MCU or AP), no I2C communication is possible.

[elrhoul · Accepted solution]

If the system is sending a reset command while the I2C communication is still ongoing. Then the slave is waiting for clock falling edge to change the values but the host is already in reset mode.  In this case, the SDA line will be locked to GND and only manually release the SDA line can recover from this.  To avoid such problem, reset can only be executed after one complete I2C communication is finished.