MS3 only accessible in bootloader

[hydrochloric]

Hi all, a few days ago I finished building my MS3X, and today I powered it up... And promptly got confused and frustrated.

At first I wasn't even sure if the daughterboard had firmware on it, so I spent a while trying to get that on it (which was exacerbated by trying to use a Mac with a virtual machine, then the Mac side, then discovering the FTDI Mac drivers have a bug... etc.). Finally I switched to a windows machine, but noticed that my bench power supply was outputting 21.8V! It's supposed to be regulated to 13.8, so that's something I'll need to look into anyway, but I'm hoping that didn't damage anything. I did check voltage, and the only difference at the ECU was 5.03v vs 5.00v once I had it on a proper 12V supply. Additionally, I had the JP1 pins 1-2 jumpered on the daughterboard because of the setup guidelines for my particular application (basically a FC RX7), until I realized the JP1 referred to was actually on the mainboard and wasn't named as such because it was the V3.0, not the V3.57 the guide was written on.

After removing the jumper, success! I had the bootloader jumper in place, msload saw the MS3 and identified it as such, and flashed successfully. Then TunerStudio... Well, every time I flash it (only possible in bootloader mode), TunerStudio detects it once, sometimes correctly but more often as "unknown" and occasionally not at all. After that, it won't communicate at all anymore until I reflash it.

I'm using the built-in USB, not the serial port, and I don't have a serial connection to use to try a loopback. I'll go through and re-check my soldering on the serial stuff especially, though I'm also considering removing the DB9 and associated components entirely since the USB-Serial converter is clearly working... Sorta.

I'm open to any advice! Luckily this isn't holding up the project, but I'd still like to get it sorted.

[hydrochloric]

Something was wrong with the mainboard's serial setup. I don't know if I damaged the IC, or there's some other issue, but once I removed all the serial components off the V3.0 board, the MS3 connected fine and talks to TunerStudio.