This project also can be the starting point for other data-logger applications, for example measuring temperatures etc. I implemented a few functions that automatically open a connection and send data, kind of fire and forget approach. The AT-Commands are now a bit more designed to be readable by humans as this is a standalone solution (but of course it can be used in context with a µC or something) so for example if there is a typo or you called a command wrong, it will tell you what was wrong.
The conversion to a cyclic logging instead of an event based one is very simple. An external sensor or the ADC(not really accessible on the breakout I have, [Tout pin] can be used to measure the values.
Currently I am polling the pin... there are interupt available but I was not able to make them work
currently the config for the logger is lost after reset, need to be written to the flash
Temperature only measured on event. this will result in an average that is not really the average of the day. For me this is ok as I just want to see tendences but this can be improved.