APM 2.x / MP Version Compatibility

I recently acquired some unused APM 2.4 and 2.5 boards. Understanding that I need to use the correct legacy firmware for them, which version of Mission Planner would be best to use? I loaded copter 3.2.1 into a 2.4 board and MP connects, but it seems to lock up when I attempt to calibrate the IMU and does not seem to show any compass activity. I have not tried anything with the 2.5 board yet. Thanks for any direction on this!

Those boards are over seven years old. So get a Mission planner from 2015 and it will work fine.

Right on, thanks for confirming that. I’ll probably be back.