The Real-Time Clock card (RTC) uses the NXP PCF2123 and a CR2032 battery to keep time of day even when your robot or other automation is unpowered. It has an active low alarm output that can turn on your robot or automation at a preset time. The alarm output is designed specifically to driver the remote-on input on the PD25 and PD15 cards.
- NXP PCF2123
- CR2032 battery backup
- Alarm LED and open-drain output
- Alarm output can control power-ON on PD25 or PD15
- Uses the ESPI 7474 circuit for reliable operation
The schematic and layout of the RTC are shown below. The Eagle schematic and board files are available here: rtc.sch and rtc.brd. The bill-of-materials file is available here: rtc.txt.