Getting started with IR, specificaly controlling tvs?

rwgast_logicdesign · 2012-07-31 20:49

So I had an idea for a project im pretty excited to get started on! It involves communicating with TVs via IR. So I went to radio shack and got a little bag with 1 reciver and transmitter, I also have plenty of old junk I can recyle IR LEDs out of to experiment with.

What I was wondering is are all IR led transmitters compatible with recivers, they dont have to be tuned to a certain wavelength or something do they? i.e the IR led set I just bought should work with a TV? And also does anyone know where to get started finding out exactly how to pulse the LED at a certain TV, I would assume this would be published info for universal remote manufactures but im really not sure how to search google for this info, just keep coming up with remote codes!

ElectricAye · 2012-07-31 21:05

You might have a look at this to get started:

http://www.parallax.com/Portals/0/Downloads/docs/prod/sic/WebIR-%20v1.1.pdf

You can also google site:parallax.com ir remote etc. and see what comes up.

Also, look on the OBEX:

http://obex.parallax.com/objects/search/?q=codes

rwgast_logicdesign · 2012-07-31 23:39

ok thanks for the links its helped me get started. one thing i cant figure out is that the ir reciever that came in my pack is just a two lead clear led, no data pin casing or anything, does anyone know what do woth it its not like any of the recievers in any of those links or tutorials ive read.

LoopyByteloose · 2012-08-01 00:17

For many years now, I have wanted to do a proper IR project. Almost everyone only gives examples of how to code 12 bit Sony TV controls, but the world is much bigger than that.

I discovered a Linux project that allows you to decode any IR device and to exploit any remote control that you have. Search and download of copy of the "Linux Infrared HOWTO" and consider using Linux as a way to research and decode remotes. It will save a lot of time and Linux can always be installed as a second OS via a dual boot. You don't have to dump Windows to have Linux available.

There are two Linux projects -- the Linux/IRDA project and the Linux Remote Control project. You probably want the second.
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And yes, transmitters need to be modulated at a carrier frequency - often around 38500 Khz. The world is full of IR noise and the receivers are tuned to ignore most of it. If you were to just try to receive the whole world of IR, you would have 60 cycle hum from lights and heat from all sorts of sources.

rwgast_logicdesign · 2012-08-01 04:50

ok thanks for the links its helped me get started. one thing i cant figure out is that the ir reciever that came in my pack is just a two lead clear led, no data pin casing or anything, does anyone know what do woth it its not like any of the recievers in any of those links or tutorials ive read.

PJAllen · 2012-08-01 05:44

Propeller Chip
Forum for all Propeller related discussions, including the HYDRA.

ElectricAye · 2012-08-01 06:00

Maybe this will help you in regards to using your specific Radio Shack components:

http://www.radioshack.com/graphics/uc/rsk/Support/ProductManuals/RadioShack_DIY_March_POTM.pdf

ElectricAye · 2012-08-01 06:01

Loopy Byteloose wrote: »

...
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And yes, transmitters need to be modulated at a carrier frequency - often around 38500 Khz. ....

Looks like a typographical error. I think Loopy meant 38500 Hz.

JonnyMac · 2012-08-01 07:05

I wrote a column on SIRCS TX and RX for Nuts & Volts that may be helpful

-- http://www.parallax.com/Portals/0/Downloads/docs/cols/nv/prop/col/nvp4.pdf

Note, though, that I've updated the drivers so that the PASM code is compatible with PropGCC. The updates (that were used in the DEFCON 20 badge) are attached.

Toby Seckshund · 2012-08-01 08:41

There are other carrier frequencies used, some as high as 56KHz, but those are not common. The receiver modules have band pass filtering in them, usually it is around the 38KHz region and they are reasonably fussy. The protocols then sort out a lot of different device types. I have only messed with NEC, Sony and Philips's RC5.

There is a toggle bit on some of them so you can tell if this is a fresh button push or the continuing stream of a previous push.

TV Begone is a great device, until somebody susses it was you !

LoopyByteloose · 2012-08-01 08:46

Darn typos - yes 38.5 Khz. But they do vary.

If you got just a clear LED for a receiver, that is not enough. Sure, it will receive IR, but the whole bandwidth as it doesn't filter out anything. It is useless. I know as I have a few. You can use them with a laser pointer to receive a trigger down at the bottom of tube and that is about all.

Ragtop · 2012-08-01 09:25

MagicIR in the Object library.

I have a remote control project that I am documenting in the project forum

This thread also has a list of the common IR freqs which can be set in the Magic IR object.

Beau Schwabe · 2012-08-01 10:10

In addition to MagicIR and others mentioned, here is something that I put together as more of a debug, but it contains the right building blocks to be a fully functional Universal 'learning' IR transmitter/receiver.

- It implements a compression technique to store the mark/space timing of the IR code so that it can be reproduced reasonably accurately.
- Automatic bit detection
- Manchester, fixed mark, or fixed space detection

Tested Remotes:

BIONAIRE             - Wireless floor heater
PANASONIC            - TV/VCR                
RCA Generic          - UNIVERSAL             
Phillips             - DVD/VCR Player        
JVC  (RM-V715U)      - VIDEO camera         
SONY (RMT-V154A)     - TV/VCR                
SONY (RM-736)        - TV/VCR                
SONY (RM-D190)       - CD PLAYER             
Technics (SH-R808)   - Radio/Tape/Turntable  
Chrysler Auto Remote - Rear Seat DVD remote 
Generic DVD          - DVD Video / TV       
iLive (IBCD2817DP)   - Radio/CD player      
Credit Card Remote   - Generic 008                                          
Polariod (RC-6007)   - Camera

PST example serial output:

Bit Count for current IR code sequence:
13

Compressed IR Code sequence (includes timing data): - see DAT section of this program
32310A190A0C0B190A0D0A190A0D0A0C0B190A0D0A0C0B0D0A0D02

Bit Pattern: Fixed Space/Manchester
..1.1.11.1111

Bit Pattern: Fixed Mark/Manchester
............1

blittled · 2012-08-01 11:28

Radio Shack carries a 38kHz IR receiver http://www.radioshack.com/product/index.jsp?productId=2049727. I have one but as with most RS stuff it didn't come with any documentation so I never got it to work right.

Edit: I bought it long ago before comments were on their site and I just noticed the comments give some info on how to use it.

rwgast_logicdesign · 2012-08-01 14:02

Wow guys thanks that is alot of info plenty enough to get me going! Someone had mentioned the TV-Begone that was the insperation for my project acually, I figured you could make the propeller do the same thing in 1/8th the time of the attiny and it would be alot cooler if there was a channel up/down volume up/down so when you cant get the waitresses attention you can just change the channel yourself

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Ok the one thing im not real clear on still though i have an 850nm wavelength transmitter to get started with, i know there are 950 ones too, do certain sets use certain leds?

Mark_T · 2012-08-01 16:11

Just to clarify some confusion I saw earlier - the infra-red wavelength used for remote controls will not pick up heat radiation at all - its very close to visible red light and temperatures of 1000's of degrees are needed to start radiating this appreciably - so heaters/heat sources won't be detected, but most white light sources will be. Sunlight is the main problem as its far brighter than anything else and can saturate the photodiode input circuit.

The Infra-red part of the spectrum covers a vast range of wavelengths from 1mm to 750nm, over 1000 to 1 ratio. Heat radiation of everyday objects is somewhere in the middle of this range. IR sensors for this heat radiation range are basically very sensitive heat detectors rather than photodiodes and are many orders of magnitude slower to respond to change.

Moutasem · 2012-12-11 12:10

Hello Everyone,
One of my project ideas is to build a Boe-Bot with multiple IR transmitters, and I might not have as many as I need. Would removing IR transmitters from a TV remote control work with the Parallax circuit-board and if so does it work on the same frequency?
Thank you.

Peter Jakacki · 2012-12-13 06:10

Funny thing is that one of my first uses for my 3.5" touchscreens will be to replace all my remotes including those so called universal remotes. The unit won't be much bigger than the 3.5" touchscreen and I am including IR leds as well as an RF transmitter to send to slave IR leds plus I will use the IR LED(s) as a receiver to learn the carrier frequencies and codes of the other remotes. The thing with the touchscreen is that I can change the buttons dynamically to suit what I'm doing so I won't be hunting in the dark for that mute etc. The remote will also control several devices simultaneously so that everything switches in harmony (not that harmony).

Pity these IR remotes don't include codes to actually turn the power on or off because it seems that many just toggle the power, so frustrating. Many moons ago when I did networked TV control systems for hospitals etc the lack of this feature necessitated power sensing circuitry, normally in the mains, to make sure it was on or off.

Mike Green · 2012-12-13 07:56

Most of the comments (and examples) mentioned here make use of an IR detector which recognizes only modulated IR with a modulation frequency of 38.5KHz or 40KHz or something like that. The RadioShack package you mentioned contains only an IR LED and an IR phototransistor which is missing a whole lot of stuff inside to amplify the IR signal, filter it, and detect a specific modulation frequency. Look at the datasheet for each to clarify what the differences are.

LEDs and phototransistors are designed for specific wavelengths of light. They don't respond well to light of a different wavelength. The datasheets show the response curves.

Getting started with IR, specificaly controlling tvs?

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