I hope I'm in the correct category. Board - UNO.
I have some surplus Futaba 2x20 VFD modules, probably intended for POS terminals. Mfgr probably ~ 2010, I've had them a decade.
When I got them, I hooked one up to the desktop and used a terminal program to talk to them, so they work. Only 3 wires, 5V, GND, and "232". Pretty straightforward.
The Uni is clearly talking, and the same setup speaks correctly with a very similar Futaba VFD interface, although that one (with graphics mode) requires a three word 'opcode' before the data word, yet this one only displays garbage.
The displayed characters are valid, and the pattern somewhat consistent .. but I can't command ASCII "A" for example. Instead it may display the Greek Iota.
Tried playing with baud rate, parity, stop etc, with different results. Sure seems as if either a timing issue or word length.
Oddly .. with playing about, I still seem to have less instances of letters A-Z than expected in the garbage. I've pretty well exhausted head scratches.
The Uno manual lists the supported baud rates, but I have noticed I can type a random number .. like 7500, and the IDE returns no errors. Is the board actually sending at 7500, or is defaulting to one of the rates listed?
Played around with delays between characters, no help.
Here's my bit of test code: Don't know why my loop starts at 20 .. probably a typo, but irrelevant.
.
int a = 20;
void setup() {
Serial.begin(9600, SERIAL_8N2);
delay(5000);
Serial.write('A');
delay(a);
Serial.write('B');
delay(a);
Serial.write('C');
delay(a);
Serial.write('D');
delay(a);
}
void loop() {
for (int x = 20; x <= 255; x++) {
Serial.write(x);
delay(100);
}
}
Note that the display is not scrolling through all 256 characters, but seems to prefer about 20 or 30.
Can anyone throw a guess at the side of the barn?
I know 232 has evolved in the last 50 years, but I doubt the display is looking for a +/- 12V swing on a relatively modern 5V board.
I guess today I'll try inverting the data signal .. don't know why but it'll only take 5 minutes and a transistor.
Any help would be appreciated.