Add telemetry support for cellular networks (GPRS)

[amotl]

TinyGSM integration

The coolest thing would be to support quite a bunch of GSM/GPRS modules by bringing the excellent TinyGSM library to the world of MicroPython. We mentioned that idea within stinos/micropython-wrap#3 and vshymanskyy/TinyGSM#362 the other day.

Pure-Python SIM800 support

On the other hand, using a specialized pure-Python module for supporting the SIM800 module at least is probably one of the more lower hanging fruits right now. We researched this topic already [1] and now found the implementation by @sarusso to be the most promising to integrate - thanks a bunch! We will further discuss that topic on our forum [2].

[1] https://community.hiveeyes.org/t/micropython-libs-for-sim800-on-esp32/1492
[2] https://community.hiveeyes.org/t/unlocking-and-improving-the-pythings-sim800-gprs-module-for-micropython/2978

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cc @poesel, @thiasB, @ClemensGruber

[amotl]

f3f892b is just a first attempt integrating SIM800 support and has not been tested yet. @ClemensGruber or @poesel might want to give this a try. Thanks again, @sarusso!

[amotl]

We have been working on that (see also [1]) and want to note that the implementation worked out well.

In order to configure Terkin for JSON over HTTP over GPRS uplink telemetry, just use these snippets within your settings.py configuration:

• SIM800 network configuration
• GPRS telemetry configuration

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[1] https://community.hiveeyes.org/t/unlocking-and-improving-the-pythings-sim800-gprs-module-for-micropython/2978