I want to use a mini or nano or some such on a board I am making.

I need to have the ability to add a data logger and RTC at some point, but that will be more of a rare option. to that end, I want to install the board with holes for a data-logging shield. when I laid out the pro-mini, the connections between the two boards seems like there is no sense of alignment. then I realized the pro-mini was designed to be plug and play with the Basic-Stamp. so, I grabbed a NANO and found the I/O pins were aligned but the other pins, power, ground and such were not.

anyone know if there is some variant of small board that is directly pin for pin with a data logger/RTC sheild? I cannot use an UNO or full sized board and then stack. my case will not handle two stacked boards.

This one ?
That is a ‘shield’ to be used with an Arduino Uno and other boards like that.
Do you have to use that shield ? Or can it be a seperate module for SD and RTC ?

I see that the Adafruit shield is the most common. My project is a simple home alarm. couple of window and door sensors and some motion sensors. I want to data log any trip times when the unit is in set mode. the data logging will be a debug action if there are false alarms that cannot be accounted for.

had one that would go off in the middle of the night, could not figure out what was tripping it. the data logging will only be installed after there are unknown false alarms.

I am looking at the added cost of just putting the data logger and RTC on every board and then only installing an SD card for actual data logging when there is a problem.