Mitsubishi Ac Remote Decoding

[easy electronics]

Hi gurus .

i want to hack this remote.


i just want to resist temperature + and temperature - key.

i have read its wave and here is image.

i have analized that
every time i press any button , the remote send current status on remote.
so every time when i press start or stop it also send current temperature status of remote (remote lcd).

i want to know that what are protocol of this remote like NEC, RC5 or any other .

i want to block only temperature keys .

Is it possible .

 

[betwixt]

One image alone is insufficient to decode the pattern. Most sequences are made partly from an address and partly from data, the first thing to do is compare the sequences from all the keys to find out which part is constant (the address) and which part is different from one key to the next (the data). Repeat the process several times and compare the first and subsequent presses of the same key to make sure you get the same sequence. Some sequences, for example RC5 have a "first press or repeat" bit which is changed after the first press of the key to indcate it has been held down rather than released and re-pressed, comparing waveforms will demonstrate this and give a strong clue it may be RC5. Also consider that RC5 and RC6 protocols are licensed so some manufacturers avoid them to save costs.

Also consider that most protocols are protected, typically by sending the same data twice but with the data inverted second time. This is not the same as inverting the waveform you are monitoring, it means the bit that created the waveform is reversed so whatever produces a '1' pattern in your waveform produces a '0' pattern instead and vice versa.

How did you extract the waveform you show? Is it IR or RF and did you monitor at the sending end or receiving end?

Brian.

 

[easy electronics]

Thanks brian for your reply.
i have decoded RC5 and NEC remotes and worked well.
but in this case
as i have mentioned that every time remote sends current status of all keys.
for example if we only press temperature + button
remote will send all of data displayed on lcd + current temperature code.
i mean
Temperature data+ timer status + timer value + fan + mode data.
so every time temperature code will be different depends upon current remote condition.

All of this stuff is basically arranged to synchronization between remote and Air conditioner .

i have connected Ir receiver to mic and extracting data from software "ir protocole analizer ".

i have saved 10 samples of each keys of remote and analysed all this information .
4ms low + and 2.5ms + high start pulse and + data bits .
i just want to block temperature temperature keys without touching ac circuit and Remote .
again thanks for your reply.