Battery Level Status (BLE)

• The Battery Level Status characteristic is now supported for all BLE implementations (not to be confused with the Battery Level characteristic). This characteristic reports battery presence, power wire presence and charging/discharging status to the host computer.
• Unfortunately, MS Windows does not take advantage of this information yet. So, this release does not make any difference to the end user.
• According to the Battery Service specification, the Battery Level Status characteristic is optional, so most phone and desktop applications also ignores it.
• Now, the reported battery level will be 0% if there is no battery attached or the battery monitor is not configured properly.
• The firmware can detect whether the battery is being charged but cannot determine a reliable battery level in that case.
  It therefore reports a constant 66% battery level, preventing unwanted "low battery" warnings on the host computer.
• Custom setups not having a battery will report a constant 100% battery level to the host computer.
• There are two new, optional, public, API calls in the batteryMonitor namespace:
  • setExternalPowerWitness(): use a GPIO pin to sense wired power. The firmware has no use for this right now, but wire presence is reported to the host computer via BLE. In case you want to use it, you must drop the power wire voltage to 3.3V before it gets to the GPIO pin. A voltage divider should do the job.
  • setChargingWitness(): use a GPIO pin to detect if the battery is being charged. The battery charger chip should provide this signal. When not used (the default), the firmware will make a guess.

Full Changelog: 7.7.9...7.8.0