The device received an additional byte beyond the required number of bytes, and the additional byte failed to match the correct PEC CRC value for the byte stream.
Possible Causes:
- Wrote too many bytes (i.e. 16 bit write to an 8-bit register)
- Wrote incorrectly computed PEC byte
- Signal Integrity issues with I2C
- Perturbation of the I2C bus
Remedies and Workarounds
Here are some experiments you can try to narrow things down:
- Lower the bus speed (View > Preferences) and see if the problem goes away
- Clear the fault to see if it returns / is recurrent
- Disable other masters on the bus that may be conflicting with LTpowerPlay
- Be sure only one master is talking at the same time. Optionally you can take LTpowerPlay 'offline'
Scope Debug
- Trigger the scope on the falling edge of the ALERTB signal, and
- Look at SCL/SDA signals preceding the ALERT
- This will tell you the offending command/data sequence and may illuminate other problems on the bus (contention, etc)