Post by thread:IR

On Wed, 5 Jul 1995, Berard wrote: > I've been following the discussion on IR communications > with some interest, and have a question about the protocol > used in commercial remote control units. > > I have several hand held remote control boxes for TVs, VCR, cable > boxes etc., along with a 'multi-remote' unit that can be set to control > 3 devices. I would like to be able to use one of these commercial > transmitters to provide the control for one of my PIC projects. > > I have been playing around with the IR Control Receiver Modules from > Digi-Key (LT1033-ND 32.7 KHz), and Radio Shack (GP1U52X 40 KHz) Here's what I've come up with (with test equipment) so far. Generally the remote controls use a carrier near 40 kc, which they then key on and off at approximately 600 us per pulse (half-cycle). Message length is around 24 bits, usually shorter. There's an initial settling time that the carrier is on, before the first bit. When a key is held down, most send the code over and over. Some just send the code once, then go to a "holding pattern", where a bit or two is sent at regular intervals while the key is held. Generally I figured that if you wanted to make a "universal learning remote" you'd have to just give up and use a brute force high sample rate, like at least a sample every 250 us, preferably more than that. I figured with a PIC16C57 you could just fit the information from one blast in the 64 upper registers, then take your time writing it to EEPROM. I have yet to try this out. If you wanted to mock a particular remote, that would be much easier, as you've observed, since you can just generate from the known timings. One more thing I've found: those receiver modules are *great* for receiver applications but not so good for learning remotes. The noise from them can look a *lot* like signal. If you just use a phototransistor and do the amplification yourself, you can just let the sensitivity be very low, forcing the user to hold the transmitter right up to the detector, and you'll get a more reliable signal. Come to think of it, I've never seen a learning remote that was at all sensitive. I guess someone else has been here. David -- Their address sums up their attitude: One Microsoft Way http://www.rt66.com/dthomas/

There are a couple of good articles on IR in the current issue of Electronics Now. Title: Electronics Now (formerly Radio Electronics) Publisher: Gernsback Publications Inc Subscriptions: Subscription Dept Box 55115 Boulder, CO 80321-5115 Editorial: 500-B Bi-County Boulevard Farmingdale, NY 11735 Phone: (516) 293-3000 FAX: <none> Cost: $19.97/yr ISSN: 0033-7862 --Chuck

Hi guys do anyone know what freq of modulation do normal remote control for vcr and tv used? regards soon lee

> do anyone know what freq of modulation do normal remote control for vcr and > tv used? std. between 38 and 40 KHz Martin <spam_OUTberentsenTakeThisOuTsent5.uni-duisburg.de>

On Mon, Feb 28, 2000 at 04:48:13PM +0800, Soon Lee wrote: > Hi guys > > do anyone know what freq of modulation do normal remote control for vcr and > tv used? Normally 40kHz, but 38kHz also commonly used. Simon.

For detailed information, see: http://www.ustr.net/infrared Soon Lee wrote: > > Hi guys > > do anyone know what freq of modulation do normal remote control for vcr and > tv used? > > regards > soon lee

thanks for that If I am using other devices that uses the small frequency will it interferences, is there any way in preventing it? thanks regards soon lee ----- Original Message ----- From: Martin Berentsen <.....berentseKILLspam@spam@sent5.uni-duisburg.de> To: <PICLISTKILLspamMITVMA.MIT.EDU> Sent: Monday, February 28, 2000 5:14 PM Subject: Re: IR > > do anyone know what freq of modulation do normal remote control for vcr and > > tv used? > > std. between 38 and 40 KHz > > Martin <.....berentsenKILLspam.....sent5.uni-duisburg.de>

Sorry but i can't access the url ----- Original Message ----- From: Wagner Lipnharski <EraseMEwagnerlspam_OUTTakeThisOuTEARTHLINK.NET> To: <PICLISTspam_OUTMITVMA.MIT.EDU> Sent: Monday, February 28, 2000 11:34 PM Subject: Re: IR > For detailed information, see: > http://www.ustr.net/infrared > > Soon Lee wrote: > > > > Hi guys > > > > do anyone know what freq of modulation do normal remote control for vcr and > > tv used? > > > > regards > > soon lee

part 0 3443 bytes Neither can I.  I'm getting a Forbidden error. Regards Mike <UL> {Original Message removed}

www.ustr.net/infrared/index.htm <http://www.ustr.net/infrared/index.htm> -----Original Message----- From: Michael Rigby-Jones [@spam@mrjonesKILLspamNORTELNETWORKS.COM] Sent: Monday, February 28, 2000 8:15 AM To: KILLspamPICLISTKILLspamMITVMA.MIT.EDU Subject: Re: IR Neither can I. I'm getting a Forbidden error. Regards Mike -----Original Message----- From: Soon Lee [SMTP:RemoveMEpslnTakeThisOuTCYBERWAY.COM.SG] Sent: Monday, February 28, 2000 4:08 PM To: spamBeGonePICLISTspamBeGoneMITVMA.MIT.EDU Subject: Re: IR Sorry but i can't access the url ----- Original Message ----- From: Wagner Lipnharski <TakeThisOuTwagnerlEraseMEspam_OUTEARTHLINK.NET> To: <RemoveMEPICLISTTakeThisOuTMITVMA.MIT.EDU> Sent: Monday, February 28, 2000 11:34 PM Subject: Re: IR > For detailed information, see: > http://www.ustr.net/infrared <http://www.ustr.net/infrared> > > Soon Lee wrote: > > > > Hi guys > > > > do anyone know what freq of modulation do normal remote control for vcr and > > tv used? > > > > regards > > soon lee

hmmm, some problems at the webserver... try the direct page: http://www.ustr.net/infrared/infrared1.shtml Wagner. > Michael Rigby-Jones wrote: > > Neither can I. I'm getting a Forbidden error. > > Regards > > Mike > > {Original Message removed}

----- Original Message ----- From: Soon Lee <pslnEraseME.....cyberway.com.sg> To: <EraseMEberentsesent5.uni-duisburg.de> Sent: Tuesday, February 29, 2000 6:33 PM Subject: Re: IR > Thanks for the infor > > Is it possible to have a unique modulation freq, does it means that we need {Quote hidden}> to build our own filter? > > regards > soon lee > ----- Original Message ----- > From: Martin Berentsen <RemoveMEberentseEraseMEEraseMEsent5.uni-duisburg.de> > To: <RemoveMEPICLISTspam_OUTKILLspamMITVMA.MIT.EDU> > Sent: Monday, February 28, 2000 5:14 PM > Subject: Re: IR > > > > > do anyone know what freq of modulation do normal remote control for vcr > and > > > tv used? > > > > std. between 38 and 40 KHz > > > > Martin <RemoveMEberentsenTakeThisOuTspamsent5.uni-duisburg.de> >