Infrared Codes reading mechanism

[Wond3rboy]

Hi, i am wanting to read different types of remote control IR codes(SIRC, NEC, Philips and others etc). I intend to use the 16f628a. I wanted to ask about the best way one could accomplish this, to do this i have a few questions:

1. First, i could only find Sony's coding mechanism and that too through Nigel's Tutorials. Can anybody point me to the other company's coding mechanisms, i cant seem to find them.

2. The second one is about how best to approach this, one idea would be to select the company code being received by using the start bit(time duration being different). I could then raise a flag and then use the appropriate bit times/bit size for each company code. Ofcourse this method is only usable if we have the same kind off time duration logic being implemented in the other remote controls.

I will be using hi tech C to make things easier for me.Thanks.

 

[Nigel Goodwin]

You can't really measure bit times - the whole point of the different coding schemes is that bit timings don't accurately survive the trip as IR.

Sony SIRC's overcomes this by having a VERY wide spread of pulse widths for each type of bit, RC5 uses Manchester coding which ignores width entirely, and uses transistions (high/low low/high) instead.

 

[Robin2]

Are you trying to make a device that will respond correctly to codes sent by different transmitters?

Or are you trying to figure out what code sequence is sent by different transmitters so that you can choose the most appropriate transmitter?

 

[Mike - K8LH]

There are a few different IR protocols described here; https://www.sbprojects.com/knowledge/ir/index.php.

Regards, Mike

 

[Wond3rboy]

Hi, thanks for your replies, nice link mike, Yes Robin i am trying to make a receiver that will read codes from different remote controls, a universal remote kind off thing. Nigel, thanks for pointing out the mechanisms, NEC and SIRC use duration for the different parts of a transmission. Philips codes will be a problem with the manchester encoding so the start bit duration methodolgy wont work. Actually i got this idea from the Arduino library IR Remote. Have been pondering on making it from scratch or trying to convert it for the PIC. Thanks.

 

[Robin2]

Hi, thanks for your replies, nice link mike, Yes Robin i am trying to make a receiver that will read codes from different remote controls, a universal remote kind off thing.

It may be easier to help if you explained in some detail what you want your device to do.

I can't imagine an application where the device would have to work with any old remote transmitter that happens to come along. So perhaps you already know exactly which remote transmitters will be used. Or, alternatively (and better) you could chose transmitters whose codes are easy to use.

Then there is the question of what the device is supposed to do when it receives a signal from a remote transmitter? Again it hardly seems likely that it will have to recognize every single code and do something different for each one - that could mean 50 or 100 possible operations.

 

[Wond3rboy]

Yeah sure, the idea is to make a remote controlled extension cord(not available here locally). As far as the remote controls are concerned, i will be dealing with Sony, philips, panasonic, LG, Samsung. Have been looking at other 'simpler' options too like make a transmitter myself (takes out all the hard work cause the extension cord can also confuse tv channel changes with the cord tasks). Just thinking over what controller would be most suitable for the transmitter, something that is cheap and small. Thinking about the new 12f series but cost obviously is a factor.

 

[Robin2]

Yeah sure, the idea is to make a remote controlled extension cord

Perhaps I'm slow or just too old but I still can't envisage what your device is intended to do.

 

[Wond3rboy]

Perhaps I'm slow or just too old but I still can't envisage what your device is intended to do.

I am thinking something like this

**broken link removed**

Ofcourse with all the stuff i mentioned above.

I intended to use TV Remote control signals for turning the switches ON or Off, the problem that i just thought off now was that TV signals could unintentionally turn the switches On/Off unintentionally so have thought to make up a transmitter for it as well. the one in the link only has one switch, the module that i am wanting to make would fit in the multiple switch extension cord sockets already.

 

[Robin2]

The link you posted makes sense - up to a point.

I still don't understand why you need to be able to interpret signals from different remote control transmitters? Why not just find one that is easy to interpret and go with that. Can you get the replacement TV remote controls that can be programmed to work with several different TVs etc? If so use one of them and set it to a different type of TV than the one you own - that way there will be no chance of you switching off lights when you try to change channels on the TV.

 

[Mike - K8LH]

Perhaps the OP has a number of surplus IR Remotes, like me, left over from old broken DVD players, or such. I'd like to build something like this myself (like the **broken link removed** or the IR Widget) in order to determine the protocol being used by these remotes.

 

[Robin2]

Perhaps. But let's wait for the facts from the OP.

 

[sahu]

check it hope useful for u
infra-red-rx-nec-sony-rc5-rc6-toshiba

 

[Wond3rboy]

Hi, thanks for your replies. I have another query though. I have since scrapped using standard remote controls(cause the 'device' that i am planning to make might have TVs in the vicinity and the sent signal can also do operations on the TV). I have decided to make up a simple remote using a small PIC(12f629 preferably), i only need to send 5 codes. I intend to use the TSOP34838(only one available here locally) which only works at 38Khz, which ofcourse would need to be generated in software using a timer etc. What i wanted to ask was if any one has worked with it before, is it reliable to do this? Also, if not, than i can get a simple IR Receiver that way there would be no frequency dictation.

 

[Nigel Goodwin]

Hi, thanks for your replies. I have another query though. I have since scrapped using standard remote controls(cause the 'device' that i am planning to make might have TVs in the vicinity and the sent signal can also do operations on the TV). I have decided to make up a simple remote using a small PIC(12f629 preferably), i only need to send 5 codes. I intend to use the TSOP34838(only one available here locally) which only works at 38Khz, which ofcourse would need to be generated in software using a timer etc. What i wanted to ask was if any one has worked with it before, is it reliable to do this? Also, if not, than i can get a simple IR Receiver that way there would be no frequency dictation.

Check my PIC tutorials that cover what you need - using a timer isn't needed though, and is less accurate than simple software loops.