Elements of the PCB

Top side

1. Connector to provide 5V DC input.

2. USB connector to program the timer module.

3. Timer output terminal.

4. LED to indicate the status of the timer.

5. In-circuit programming port to attach the ST-LINK/V2 USB debugger/programmer. (Refer Firmware section of this documentation for more details.)

6. JP201 jumper, which is used to re-flash the MCU. (Refer Firmware section of this documentation for more details.)

Bottom side

The main component locates at the bottom of this module is the CR1220 battery holder. This button cell uses to back up the system time and RTC configuration.