Using UIRT to record IR codes directly from remote

[Paul M]

Hi,

I'm interested in building a UIRT primarily so that I can record the codes from remote controls for several small projects (not actually controlling the computer with the remote, although I may also use this sometime).

I previously tried reading the codes using a laptop's IrDA port configured as a serial port and using the serial watcher interface but every press off the remote gave inconsistent responses presumably due to a timing issue with the IrDA port.

What I want to know is, will the UIRT give me the raw codes that the remote is transmitting? I realise that in normal operation it converts all codes to a 6-byte string before sending it to the PC, but can this be overridden to read the raw code of the remote?

I'd also like to be able to send raw IR codes that I have recorded back out of the UIRT so that I can test my codes for the project are correct and that the device receiving the remote codes responds correctly.

The version I intend to build is the Ruud van Gessel one since it does not need a power supply and will allow me to use it easily with my laptop (e.g. for testing remote control response of my car stereo). Range is not important since I can use the device within a few centimetres of its target.

I'd like to know if the requirements I have above will be fulfilled by building the UIRT, and if so what is the best software to do this? BTW I later intend to use the recorded remote codes in a PIC program of my own in some self-contained projects possibly in-car.

Thanks for any help :)

[kari]

What I want to know is, will the UIRT give me the raw codes that the remote is transmitting?


In most cases, yes. It may have problems with some unusal remotes (wildly different carrier frequency or modulation), but most it can read quite reliably.


I'd also like to be able to send raw IR codes that I have recorded back out of the UIRT so that I can test my codes for the project are correct and that the device receiving the remote codes responds correctly.


Thats what the T in UIRT stands for, transmitting. :)


The version I intend to build is the Ruud van Gessel one since it does not need a power supply and will allow me to use it easily with my laptop (e.g. for testing remote control response of my car stereo).


Ahh, actually the very fact that Ruud's design is powered from the serial port has been causing some problems. In short it won't work on all computers. Add to that the fact that many laptops have unusually low voltages on their ports, and I foresee trouble. Having said that, it may work, and if it doesn't it can be converted for external power supply.


... what is the best software to do this?


I assume you mean the best software for communicating with the UIRT? Well, the obvious choice is Girder. It can be persuaded to do most anything in windows, and there are plugins available for the various UIRT firmwares. If you were intending to write a dedicated program, the protocol is simple enough to implement, or, if you are using Ruud's firmware, you may wish to try out the DLL on his page.

Hope this helps,
-Kári.

[Paul M]

Thanks for your help :). I suppose the transmit thing was a rather obvious one when the Transceiver bit is included in the forum name!

Ahh, actually the very fact that Ruud's design is powered from the serial port has been causing some problems. In short it won't work on all computers. Add to that the fact that many laptops have unusually low voltages on their ports, and I foresee trouble. Having said that, it may work, and if it doesn't it can be converted for external power supply.

I had wondered about that - although I have an older Digital laptop I use for these things (newer on has no serial port believe it or not - USB rules these days). It can program both PICs and EEPROM chips on a JDM programmer I built no problems using the serial port's supply, likewise it can through-PIC program the EEPROM on a smartcard using a loader file with a Phoenix programmer.

The only time I need an external supply is when manipulating a ready-programmed smartcard using the Phoenix (i.e. emulating the smartcard interface). The responses from the card tend to be incorrect without the external PSU, but this applies to my desktop PC also. Therefore I believe I should have a good chance of running the UIRT off the laptop's serial port supply.

Adding a supply would just be a case of using the 78LS05 along with associated caps etc I assume? It does make portable use a bit more difficult but if I need to do so then no problem.

Cheers,
Paul.

[kari]

Adding a supply would just be a case of using the 78LS05 along with associated caps etc I assume? It does make portable use a bit more difficult but if I need to do so then no problem.

Basically, yes. A few components become obsolete when this is done, D2 obviously and also D3 and T1 (short drain and source on T1). Also, if your power supply is in any way connected to the computer ground, you will have to switch the GND connection of the serial cable to circuit ground.

-Kári.

[Paul M]

Thanks. I'll order the parts for the UIRT then get the soldering iron out and we'll take it from there :)