The Issue
The first revision of the AIOB’s serial data transmit (labeled RRX on the board), does not work. This impacts radio programming and CAT control.
If you have bought an AIOB after 08/01/2024, this issue will already be resolved on V1.2
The Cause
V1.0 of the AIOB implemented a voltage divider to bring the 5V serial transmit from the original AIOC design to a safe 3.3v most radios expect. However, the AIOC already does this, so this “fix” ended up breaking serial TX
The Fix
This can be resolved by removing the two resistors that form the voltage divider, located here:
These can be removed even with a rather large soldering iron by dabbing it with solder first to remove both ends. No need to be particularly careful, as we dont need these resistors to work or be useable after we’re done. Just be careful not to hit any other components on the board.
Then, once these resistors are done, use the 5V RRX pad located to the right of those two resistors as the 3.3v serial transmit (the line the radio’s serial RX will be connected to).
Send in for modification
I will also do this modification for any v1.0 customers. Simply mail it to 110 N Mason Rd, Brookline, NH 03033 by October 2024 with a return label or $5 for USA return shipping and we’ll fix any you include!