Custom TV Controller Issues

[Kdog44]

For a small weekend project I wanted to build a device that can send a power command to a TV using an IR LED. My target TV is an LG ( model number : 32CL20-UA ). Online, from this source https://github.com/z3t0/Arduino-IRremote/issues/114, I found that LG TVs generally use the NEC 32-bit standard. I am having trouble determining what the actual command code, in hex, is that I need to send so the TV interprets it as a power signal. Below is a waveform received by a 38.5 kHz receiver. The sent signal was sent by the TVs' remote while the power button is being pressed. Note that the waveform is actually inverted from what was actually sent.   

[uncle_bob]

Hi

Set your sample rate on the scope to something that will get you at least 10 samples per bit at the highest likely clock rate. Look at the data with an IR sensor rather than something that is trying to demodulate it. Grab code samples multiple times. Lay them down on top of each other. You will have errors and this will let you spot them.

After a bit of looking, you *should* be able to work out a likely clock rate. Go out across 10 or more bits once you have a guess to come up with an accurate number.

At that point you can start working out what is preamble and data. Send multiple codes and see what does not change.

Yes, this is  generalized  / start from scratch approach. It does not use any shortcuts. Because of that, it's got a high chance of success.

Bob

[orolo]

I don't know anything about remote encodings, but a quick search brought up this. The "pulse length encoding" catched my eye: short pulse = 0, long pulse = 1. The initial very long pulse should be a syncing singal. Decoding the rest: 00100000110111110001000011101111 = 0x20df10ef, 32 bits if I'm not mistaken. Is that right?

[Kdog44]

The initial very long pulse should be a syncing singal. Decoding the rest: 00100000110111110001000011101111 = 0x20df10ef, 32 bits if I'm not mistaken. Is that right?

Yes you where totally correct! I was able to write an small function to modulate the data correctly and I got it to work.