I sett the realtimeclock.
I disconnected the USB cable for a few seconds
After power up, the realtime clock is zero.
I found some references to “described in the ebook” I read the ebook and other materials in the turorials, but found no reference to installing or checking the realtime clock battery.
I did find some references to batteries for other boards.
The code examples under “Time Services” led me to believe there may be a battery installed
To use the RTC hardware, we first need to check if the RTC hardware has the valid time or not. Maybe this is a new battery or the new system and the RTC has not been set yet. If RTC has a valid time then we can read the RTC (hardware) and use that to set the NETMF system time (software). If time is not valid, then you will need to set the RTC to the correct time.
But how do we check if time is valid? One way is to use the built in battery ram to store some magic numbers that we check later to determine if the battery ram data is still valid. If they are then most likely the RTC is valid. Also, it is a smart idea to check the RTC for some reasonable time. For example, check if the year is not less than 2011.