It’s pretty easy using the real time clock (RTC) on the Raptor. Connect any 3VDC watch battery across VBAT (X5 pin 5) and GND (X5 pin 10). That will keep the RTC powered up when the rest of the board loses power. Check out section 8.20 in the G400 user manual. You can use a Breakout TB10 Module, a Extender Module a G-Plug Module or the breakout board, all available from GHI. The code you need to set .NET Micro system time to the RTC is at [url]https://www.ghielectronics.com/docs/29/real-time-clock-rtc[/url] (same place you referred to in your OP)