Once the firmware has been uploaded, you need do little more than give it power and flip the ON switch. The UPOD should blink green every time a sample is taken, and blink red every time the buffer is flushed and data is written to the SD card (if SD_WRITE is configured in the firmware).
The red and green LED are used to convey common problems with the UPOD.
- If the green and red LED are flashing in sync (and SD_WRITE is configured), then the UPOD is having problems communicating with the SD card. Common problems include poorly soldered SD card pins, improperly formated or corrupt SD card and, obviously, no SD card being present
- If the green and red LED are flashing in an alternating pattern, then the UPOD cannot communicate with the real time clock. Common problems include poor contact between the 3.3V RTC battery and the board (a dollop of solder on the pad will help) or a dead battery.