Code finished, uploaded, time to take it out for a test. I wired up everything, confirmed that the IR LEDs were in fact lighting with my digital camera (FYI, IR LEDs will glow with a purple tint to them when viewed through most cameras). The first test was unsuccessful. The sign taunted me with it's “STOP MODE” message. The sign will beep on IR received but I heard nothing. So I spent some time adjusting the pulse times. Still nothing. I spent a few more hours adjusting the code without success.
Then, as a last ditch effort, I wondered what would happen if I flipped the pulses around. That is to say, instead of pulsing the IR LED at the top of the graph (1), pulse it only at the bottom of the graph (0). I made the change, uploaded the code and was rewarded with “BEEP BEEP BEEP” coming from the sign. I then tried to remember all of the other changes I made and reverted back to them.
Like any good programmer, the first thing to write is “HELLO WORLD.” It's not without it's problems, however. The key strokes aren't always received 100% which is frustrating. Double key presses (for instance, the two LL's in HELLO) need to have a long pause inserted into them or it believes the key was held down by accident. The sign is fairly old so it may not have the best equipment inside. Or I may have gotten something wrong. Anything's possible!