You're right, I'm an idiot. Of course it's lsb first. For some STUPID reason I was thinking the first bit was a STOP bit, not a START bit and got the whole thing wonky. It's been awhile since I've had to troubleshoot serial stuff.

Okay, now I've got it and it's even more perplexing that this doesn't work since the display is getting the right code. When I send out [$7A, $55], that's indeed what I see on the scope.

I think it's a timing issue and tried using DEFINE CHARACTER_PACING but that doesn't work either for values 1000 to 20000.