Infra Red Codes

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fritz42_male

Senior Member
Hi, I'm unable to search the forum at the moment (don't know why but it times out).

I need to be able to get an LCD TV to switch on automatically in an unmanned showroom. The problem I have is that the TV defaults to standby mode when power comes on (automatically at 9am). I'd like to be able to knock up a Picaxe circuit to wait 30 seconds and then transmit an ON code to the TV via IR.

I have two problems. One is identifying the on code and the other is transmitting the code. I know there are various databases I can use to hopefully get the on code but are all codes of a similar format? I know the Picaxe uses the Sony standard?

Thanks

Mike
 
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inglewoodpete

Senior Member
There are a number of standards. The major one is the NEC 32-bit standard and most household consumer appliances that have IR remote control use this format. Sony is the most common exception.

In my house, LG, Akai, Grundig and Topfield appliances all use the NEC format, so it's quite common. I presume the NEC appliances also use it :). The software I published here decodes and displays NEC code using an IR receiver module (A$7) and a 20X2 PICAXE. It also provides an explanation of how 32-bit NEC codes work.

While designing and testing the software, I used another PICAXE to generate the 0's and 1's to get it working before using one of my many remote controls to do the final development and debugging.

Some TVs can also use serial (RS232) to control them (My LG does).
 
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Haku

Senior Member
An alternate method would be to get a small universal remote that can switch the tv on and get the Picaxe to 'press' the power button. Remotes typically run off 3v and an 08m can run off 3v so powering them from the same source shouldn't be a problem.
 
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fritz42_male

Senior Member
Pete - perfect! Trust a SandGroper! Will this module be OK? http://www.jaycar.com.au/productView.asp?ID=ZD1952&keywords=infrared&form=KEYWORD


Haku - yes I'd considered that but would prefer a neater solution. The IR code solution allows me a lot more leeway as once I've sorted all the codes then I can control the TV AND the media player. This means that I can come up with a solution that also allows me to do motion activation on the Media Player.
 
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hippy

hippy

Ex-Staff (retired)
The main thing is to work out what the code sent is. That can be done with a DSO, logic analyser, sound card scope, or an IR protocol analyser which is probably easiest -

http://www.ostan.cz/IR_protocol_analyzer

There was a thread on the forum where that software was brought to our attention and how to interface to it was described but I cannot find it with a quick search so don't know who to credit for finding it. It works very well in my experience.

Once you know what you have to send it's then a question of generating a code which matches. You will probably want a PICAXE which can run quite fast ( 32MHz or 64MHz ) to get fine adjustment over timing but there should be some reasonable leeway in timing.
 
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westaust55

Moderator
Yes that is the right type of IR receiver given in your post 4 link.

Check they are selling the 38 kHz version if possible.
 
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inglewoodpete

Senior Member
@fritz: Jaycar's ZD1952 is what I used for the 20X2-based version. It is wired as per the diagram in Manual 2's "IrIn" Command. The ZD1952 is the "38 kHz version" that WA55 refers to. It should also work fine on the input of the soundcard.

I have used the soundcard as a sampler for an oscilloscope before I got a "proper" one but never used it with an IR phototransistor.

The PC-based IR protocol analyser that hippy refers to was quite recent.
 
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fritz42_male

Senior Member
All very useful - thanks guys.

Westaust55 - I had assumed that someone would have been looking at IR stuff before but I was unable to search the forum at the time. The forum was running very slowly and searches were just locking up.

Thanks again. Picking up some parts today.
 
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inglewoodpete

Senior Member
4:00am UTC is the time the webservers appear to do their backups. Trying to do anything on the forum between 12:00 and 12:15pm W(A)ST is near impossible.
 
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John West

Senior Member
inglewoodpete said:
4:00am UTC is the time the webservers appear to do their backups. Trying to do anything on the forum between 12:00 and 12:15pm W(A)ST is near impossible.
Click to expand...
I've noticed that on more than one occasion. That's about 10:00 PM here in CO, USA, so I run into it a lot.
 
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John West

Senior Member
hans99 said:
Here is the Manual!

Regards,
Hans
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I note that I did not properly thank hans99 for providing the manual pdf. I'm not sure why I could not download the original from the site, but strange things seem to happen on a regular basis on my computers.

Thank you, hans99. The info looks good and the program is handy and just what I need right now, what with all of the old remotes I have lying around.
 
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