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Decoding an IR remote RC2094501/B but getting random codes
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oPossum:
The RCxx codes use Manchester coding, so they require IR receiver modules that have symmetrical carrier on/off response times for reliable decoding. Most other CIR protocols care mostly about the time between bursts so they will work with almost any decoder module even if it is quite asymmetrical and the wrong carrier frequency.
 
I created a simple way to do IR capture that provides both timing and carrier frequency information. The web page is here: http://compendiumarcana.com/irwidget/
There is also an AVR version here: https://forums.adafruit.com/viewtopic.php?t=4890
and a MSP430 version here: https://forum.43oh.com/topic/695-consumer-ir-cir-capture/

Currently working on a CH551 version.
Samishkakumble:
Excellent post! I go valuable information here. Thanks for such an excellent piece of information!
Clockwerk:
update

I have acquired a cheap Sigrok compatible Logic Analyzer (24Mhz 8ch) and the DSO138 which I know are basically toys but can help a lot with low speed / basic signals like in this case. Whereas I still have to actually learn how to use them properly, I made some improvements on this matter. Turns out I could try with a TSOP38338 which shows some consistency and better results compared to the other IR receiver I was using (TSOP4838).

As per the datasheet, the best option would actually be the TSOP38336 which is 36Khz and specific for RCMM but I don´t have it yet to compare.

Nevertheless, this time capturing the data looks promising:



Zooming out and timing set



Any insights or comments about the above signal would be appreciated.


Note to @oPossum

Thanks for your valuable information, I was unaware you can use any led to actually receive. Also, I will borrow some TSOP98200 to play with following your post, as it makes more sense to play around when you don´t know frequencies or protocols. Nice job.
soldar:
I faced a similar issue some time ago. I will share the basics in case it is of any help.

The IR carrier is detected by the receiver so the receiver outputs the modulating signal. It helps a lot to deal with the detected signal.

This I recorded by using the audio input to the computer. I recorded the data of each key several times and I found that the modulating signal carried 27 bits of 8.88 mS, about 240 mS total. As long as the key is pressed the same code is repeated at about 4 times per second.

First bit is always 1 (start)
Bits 2 and 3 always 01 except in a couple of keys.
Bits 4 and 5 alternate between 01 and 10 each time the same key is pressed.
Bits 6 to 15 always the same combination. I imagine identifies manufacturer and device
Bits 16 to 27 carry a different combination for each key but never carry more than two ones or two zeros consecutively

I assume there are many different systems but this might give some idea of the philosophy behind them.
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