TS-4100 CPU RTC
From embeddedTS Manuals
On this platform, the NXP SNVS Low Power Realtime Clock (RTC) module inside of the i.MX6UL CPU is used at the hardware clock. This is presented as "/dev/rtc0" from the Linux kernel and is accessed using the standard hwclock command. In order to keep time, there must be a constant 3.3 V provided on CN1_36 to keep the RTC active.