beagleplay/test-reports/dvt/test-procedure/test_32k_rtc.md

Testing system time using 32k clock

If 32k crystal is correctly configured, then system time (as measured against realworld time measured by stop watch) should match onboard RTC time. It is a good idea to disable networking to prevent NTP from adjusting time behind our back.

you need a stop watch, and linux shell prompt on board:

cd /sys/class/rtc/rtc1
cat time;sleep 120;cat time

Start stop watch at the time of pressing enter - it should print time = 120 seconds (+1 second to account for milliseconds).

debian@BeagleBone:/sys/class/rtc/rtc1$ cat time;sleep 120;cat time
06:40:32
06:42:32

Test onboard RTC as well (to ensure 32k crystal for that rtc is working)

debian@BeagleBone:/sys/class/rtc/rtc0$ cat time;sleep 120;cat time
06:47:02
06:49:02