STM32: Check for NACK

[nefelim4ag]

stm32f0_i2c - tested.
stm32/i2c - I do not have.

Currently, HW I2C ignores NACK bit in any case.
Valid case when this is the end of the transfer.
With this change, it will correctly report NACK instead of an empty read or timeout.

reproduce:

def _init_sht3x(self):
        ....
        logging.warning("sht3x: start read with stretching")
        self.i2c.i2c_read(SHT3X_CMD['MEASURE']['STRETCH_ENABLED']['HIGH_REP'], 6)
        logging.warning("sht3x: stop read with stretching")
        logging.warning("sht3x: start read without stretching")
        self.i2c.i2c_read(SHT3X_CMD['MEASURE']['STRETCH_DISABLED']['HIGH_REP'], 6)
        logging.warning("sht3x: stop read without stretching")

Output with patch:

Configured MCU 'host' (1024 moves)
sht3x: start read with stretching
sht3x: stop read with stretching
sht3x: start read without stretching
Transition to shutdown state: MCU shutdown
Dumping 7 requests for client 140733793436160
 .....
MCU 'mcu' shutdown: I2C NACK error encountered!
 .....
Printer is shutdown

Thanks.

---

#6674

[KevinOConnor]

Thanks. In general it seems fine to me. I think we should avoid adding punctuation to error strings (in keeping with existing messages) - so no exclamation mark.

-Kevin

[nefelim4ag]

Oh, I just thinking about avoiding increasing ROM size, so just reused https://github.com/Klipper3d/klipper/blob/master/src/atsam/i2c.c#L139
But this is a different mcu.

Np, updated.

[KevinOConnor]

Thanks.

-Kevin