Feature: Get battery charge status on connect

[wementoat]

Ideal Scenario / User Request

When connecting to a STH (or even just listing them), users want to see the battery state to gage if the STH needs charging.

Current Situation

You can only see the charging state if you take a measurement with the battery voltage included, and you would need to know in which range this voltage is usable.

Possible Solution

I am unsure as to where and how we should implement this - maybe this request is better suited for or should be first adressed in an underlying library. Any comments are appreciated.

[sanssecours]

I talked with @bertlderschreckliche, @LoydIrrving and @PPelzmann today about this topic.

Ideally for something like this we need an extra chip that monitors the amount of discharge from the battery. This should be the case if we switch to new hardware e.g. from Nordic Semiconductor.

In our current situation we can only monitor the supply voltage, which changes depending on the current battery status. I added an issue about this topic to the ICOtronic repository. After we implement this functionality we should be able to use

• SensorNode.get_battery_charge or
• SensorNode.get_battery_status

to read the current state of charge after we connect to the sensor node. I still need to check, if it is also possible to read the supply voltage before connecting to a sensor node.

Implementation

• Determine, if it is possible to get supply voltage without connecting to sensor node