Once the GPS module goes into standby the i2c stops working, you can no longer wake it up via i2c, all you can do is a reset via the pytracks deep sleep function.

@fsergeys said in Changing the GPS frequency and configuring which NMEA sentences the gps posts.: GALILEO and GALILEO Full satellites Do you know what the difference between the two is? Also I wonder what is the default configuration for the tracking system? I think the application note regardig I2c mentions to perform a dummy write after each command prior to get back to reading see my example here: https://forum.pycom.io/topic/2442/pytrack-and-gps-balloon-mode/3 and the sequence chart in the application note: http://www.quectel.com/UploadImage/Downlad/Quectel_L76-L_I2C_Application_Note_V1.0.pdf <- requires login. and here is the code to perform checksum testing yourself: requires the sentence to be a bytes object. def _checksum(self, sentence): l = sentence[0] for c in sentence[1:]: l = l ^ c return l def _test_checksum(self, sentence): if self._checksum(sentence[1:-3]) == int(sentence[-2:], 16): return True return False