# FAQ

# Hardware related

1. Is my USB IrDA dongle supported by LIRC?
   No, it's technically not possible to use USB IrDA dongles (as specified by the Infrared Data Association) with LIRC. This does not apply to USB receivers in general.
2. Can I use my home-brew receiver and transmitter on the same serial port?
   Yes.
3. The value of the resistor in the receiver circuit is labeled as '4k7' Ohm. Is this 4.7 Ohm, 4.7 kOhm or what?
   4k7 Ohm means 4700 Ohm. k is the abbreviation of kilo.
4. Can I use a home-brew LIRC receiver with a Serial to USB adapter?
   No, this won't work. But there is a project working on a dedicated USB transceiver or you can connect an IR receiver to a FTDI based USB chip. Using an Irman with USB adapter should work though.
5. I have a Hauppauge TV card. Can I use a different remote control with this TV card except the original Hauppauge remote control?
   The Hauppauge remote control uses the RC-5 protocol. You should be able to use any TV remote control that uses this protocol. Common brands that use this protocol are Philips and Marantz. A short description how to setup LIRC with an universal remote control was posted on the mailing list.
6. How do the drivers for the home-brew receivers work? Do they use polling?
   No, the serial port driver is fully interrupt driven. On each edge of the IR signal the interrupt handler is called and the time since the last interrupt is calculated. As the parallel port only generates interrupts on the rising edge of the input signal, the parallel port driver uses polling with the help of the hardware timer until the signal becomes low again. As it is polling only for microseconds this has no noticeable effect on system performance.
7. I would like to connect an LCD display and an home-brew IR receiver to the same serial port. Will this work?
   No, unless somebody writes a driver that merges the functionality of the kernel serial port driver and the lirc_serial driver. This is not trivial.
8. I need a IR transmitter device to control my TV/VCR/Settop box. But I'd rather buy a device than solder my own. Where can I buy LIRC compatible transmitters?
   Check the driver documentation in the configuration guide. Here is several commercially available devices including IrToy, IguanaIR and Tira.

# Software setup

1. I have trouble to create a working lircd config file for my remote. What can I do?
   Please read the documentation about how to add new remote controls.
2. Which kernel module do I have to load for my hardware?
   The documentation contains a detailed list how to setup the various devices supported by LIRC.
3. When I run irrecord or mode2 I get an error message like this:

       mode2: error opening /dev/lirc0
       mode2: Device or resource busy

   Another application is probably already accessing /dev/lirc0. Only one process can use the device at a time. You can find out which process uses the device by calling (as root) fuser /dev/lirc0.
4. Most of the time I have to push a button twice for LIRC to recognize it. What's wrong?

   The remote control probably uses the RC-5, RC-6 or RECS80 protocol, but irrecord wasn't able to recognize this correctly.

   Try running irrecord remotes/generic/RC-5.conf, irrecord remotes/generic/RC-6.conf or irrecord remotes/generic/RECS80.conf. You will find these template config files inside the LIRC source package. If this won't work read this.

5. Every time I press a button on my remote control irw will show at least 5 events (or any other number > 1) independent of how short I try pressing the button.

   In most cases this is the correct behavior. Many remote controls send the same code multiple times to make sure that at least one code comes through to the receiver when you press a button for a short time. The default .lircrc setup ignores repeat events. If you want to use the button to do things repeatedly when it is being hold down, like e.g. increasing the volume or something similar, you should use the delay token (will be available in 0.7.0) in your .lircrc file.

   You can identify such remotes by the fact that irrecord usually will add a min_repeat field for this remote control to the lircd.conf config file.

   If you want to suppress those repeats already at lircd level, you can also add suppress_repeat x to the lircd.conf config file where x is the number of repeats you want to suppress. This feature is available in lircd since release 0.8.6.

6. Only root can run LIRC applications. When I run LIRC applications (e.g. irexec) I get this error message:

           irexec: could not connect to socket

   Check the permission of the lircd output socket, usually /var/run/lirc/lircd. These permissions are defined in lirc_options.conf, the permissions option. You might need to remove the device and restart lircd for this to be effective.

# Misc

1. I need a config file for <brand> <device>. Do you have such a config file?
   If it's not on the website, then I don't have it. Please don't ask me for config files.
2. Do you speak German?
   Please only use English when sending emails.
3. Why didn't you answer my mail?

   I get way more mails than I can handle. If you don't get an answer to your question the probability is very high that you will find the answer in the documentation.

   Mails about Total irRemote will go to /dev/null unread.

# HOWTOs

- Learn how to control everyone's favourite XMMS with a TV remote - PDF (2348 kB)
- Illustration how to build a serial port receiver
- Setting up LIRC on Mandrake
- Leadtek Winfast TV 2000 XP Deluxe on Fedora Core 3 (Lithuanian)
- Description how to build a serial port receiver in Spanish

[LIRC Homepage]