Thanks for your fast reply Kurt!
Ah, I see. I’m using this IMU from sparkfun, an older version of the one you posted. Looking at the schematics, like you suggested the only option would be MOSI (PB3) or MISO (PB4). I hope they can be access in the code, maybe just check PB4 before sending serial?
If not I could simply use an external OR gate or a NAND gate (use a 2. NAND for inverting the output of the first NAND). I think I’ve some old TTL and CMOS chips somewhere… I’m currently using a level converter, but I’m not sure if its needed since it worked fine without while running the test code on another ARC-32. I started using the level converter when I noticed the bug started when RXD-BAP went low without sending any data from the IMU, and to make sure the bug didn’t occur due to 5v vs 3,3v issue.
Thanks!