The third (and hopefully final) revision has:
- Ability to measure battery voltage
- I2C EEPROM (on I2C0 - same bus as the accelerometer)
- A ‘battery low’ LED
- External circuitry (D-latch) to turn on and off the whole unit, drawing only 1uA when off.
- The ability to turn on the unit by booping the bottom half of the Wio Terminal. The unit can turn itself off by bringing a GPIO high.
I also did a battery test today. With almost all the peripherals on, the screen and accelerometer running, but without WiFi running, I get a little over 3 hours with an 850mAh cell (4.2V --> 3.2V)