I'm hoping someone has insight into the code used to sense the battery voltage on pin PB09 of U1. The schematic shows a voltage divider of R8 (330K) and R9 (1M) wired to pin PB09 of the processor. Based on the divider values I see this will limit the voltage input on PB09 to 3.3V when the battery is at 4.4V. Clearly this indicates that the battery voltage can be read and utilized by a program. What is the name of the variable and/or is there some documentation regarding this? Many thanks.