TODO
----
-- USB connection check
-- BT on/off check: whether RX line is pulled up?
+- Lipo voltage ADC sensing
+- Lipo charger configuration: fast charge time: USB charger spec?
+- Low voltage alarm: LED indcates voltage of Lipo
- CTS/RTS lines are needed? just connect in loop back if no flow control is needed.
- CTS is needed for waking up from deep sleep?
-- USB/BT switching BT is on -> BT, BT is off -> USB
-
-- Low voltage lock out LVLO of DC converter for protection of Lipo
-- Lipo charger configuration: fast charge time
-- Low voltage alarm: LED indcates voltage of Lipo
-
-- Power saving: HHKB scan, BT radio control
-
- Serial API callback when data are available/received(and when send buffer is available)
- Serial API instance several serial ports can be used
+- DCDC converter: squeaky inducter with onsemi NCP1402
+- Lipo charger MCP73831: needs capacitor 4.7uF *2
+- Keymap layer bug: during space is pressed(mousekey) press Fn(HHKB) then release space before Fn, in result HHKB layer is locked(toggled) unintentionally.
+
+DONE:
+- USB connection check - 07.01
+- BT on/off check: whether RX line is pulled up? - checking RTS 07.01
+- USB/BT switching BT is on -> BT, BT is off -> USB - 07.01
+- Under voltage lock out UVLO for protection of Lipo - Lipo has discharge protection at 3.100V 07.01
+- Power saving: HHKB scan, BT radio control - 9h with 850mAh, this is enough 07.01
+- Power selector doesn't work; Q4 MOSFET leaks from Lipo to USB power line. -- use Schottky instead 07/04
+