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I have been trying to decode Infrared Protocol used in a set-top-box.I have tried comparing with standard protocols but it doesn't match. I am using an Arduino Uno with Arduifruit IR Library's decoder sketch. The output on the serial terminal is:

Decoded Unknown(0): Value:0 (0 bits)
Raw samples(50): Gap:18904

Head: m2600  s850

0:m450 s450  1:m400 s450    2:m450 s850 3:m400 s900     
4:m900 s350 5:m400 s500      6:m400 s450    7:m450 s450     
8:m400 s450 9:m450 s450      10:m400 s450   11:m450 s450        
12:m400 s450    13:m450 s450         14:m400 s450   15:m450 s450        

16:m450 s400    17:m450 s450         18:m850 s900   19:m400 s450        
20:m450 s450    21:m400 s450         22:m400 s500   23:m400

Extent=26100
Mark  min:400    max:900
Space min:350    max:900

What I could infer from the data (Possibly):

The Header consists of Mark of 2500 i.e. 5 x 500 uSeconds and space of 2 x 500 uS. The bits mostly have equal mark and space of 500 us. Except for some bits. Is this some standard IR protocol. And do the number of bits transmitted by buttons of a remote differ.

JAL
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Suyash Singh Bitti
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  • http://www.sbprojects.com/knowledge/ir/index.php some protocols have a start pattern, some do not. normally the number of bits per button do not change unless it is a universal remote and some buttons are tv some are dvd, some set top box, etc basically if the protocol changes. some protocols have a repeat pattern which is shorter or different than the main data pattern. but no the number of BITS doesnt change for buttons within the same protocol. some protocols use long and short periods so the over all TIME may change to transmit from one button to another. – old_timer Feb 12 '16 at 16:06
  • do what you are doing then try other buttons you should see some of either the mark or space times change but overall the same number of marks and spaces. the ones with a start pattern which is what it appears you have are imo easier to decode as you have a...starting point... – old_timer Feb 12 '16 at 16:07
  • even if it doesnt line up with one of the standard ones, you should still be able to figure it out by measuring mark and space times. – old_timer Feb 12 '16 at 18:58
  • Actually i want to decode it to some hex code so that i can program an android phone with a built in IR blaster to send these signals back. – Suyash Singh Bitti Feb 13 '16 at 07:29
  • exactly. one step at a time. figure out the protocol, decode it to ones and zeros. (binary/hex) and send it to the app in whatever format you want. – old_timer Feb 13 '16 at 13:58

3 Answers3

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You can make your own device and play/decode with any infra codes using Arduino. Check this link. It is very easy.

https://learn.sparkfun.com/tutorials/ir-communication

ideeps
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  • Instead of posting links as answer add some text to explanation how this answer help to OP in fixing current issue.Thanks – ρяσѕρєя K May 23 '16 at 10:48
  • The thing you are saying above is not possible. Android phones doesn't have any infrared receivers. They only have proximity sensors. So you have to built a device. It is very easy. Follow the link I have provided. You can get the IR codes from any IR remotes like this http://i.stack.imgur.com/gePw5.png and use them. – ideeps May 23 '16 at 11:04
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The mark and spaces in range 500-1000 make me think to a phase shift coding rule. Also the variable number of bits can derive from phase shift coding. You can try with more common phase shift protocols (RC5, RC6). Here an encode/decode that can help you in investigations: https://github.com/msillano/irp_classes, it uses Arduino as RAW rx/tx and works with any IRP.

msillano
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0

I found AnalysIR tool very useful to decode IR protocols. It is no free, but cost about $10-15

ilia
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  • Thanks i saw the product seems cool. How does it works with unknown protocols ? Till now i am using Arduino to reverse engineer the ir protocols but the raw timings contain a lot of error because of arduino's speed. – Suyash Singh Bitti Feb 16 '16 at 19:19
  • They have a DB of many protocols, so probably your is a known. In my case, protocol was unknown, but visual presentation got me a clue. – ilia Feb 17 '16 at 06:49