I took a look at the Chronodot and it only has eight pins. Why is there an extra GND on the right?
I thought it could be used as a way to tell whether a Chronodot or this board was plugged in. Would require a pin on the MCU and an external pullup resistor. I looked for a way to do it strictly through software, not sure there is a good way yet, but the jury isn't quite all in on that point yet. Just in case the software wanted to take advantage of the alarms in the DS3231 on the Chronodot, or something similar.