batteader9.py for esp8266 & esp32

[sfranzyshen]

batteader9.py

[sfranzyshen]

https://www.programcreek.com/python/example/101393/machine.ADC
micropython/micropython#2352
https://forum.micropython.org/viewtopic.php?t=3054

https://github.com/micropython/micropython/blob/073b9a5eb888b26be7ce4c65e9649b6c3857ba39/ports/esp8266/machine_adc.c#L41

[sfranzyshen]

using the built in read vcc adc will not work well for battery testing because all esp's are 3.3v and have a regulator ... a external circuit connected to the external adc should be designed into the OttoDIYESPShield