Using an IR Blaster with MythTV

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Introduction

The mission: Get MythTV to change channels on my Cable provided STB (Set Top Box). I connected a cable from the STB to my tuner card, but you cannot tune/change stations using the TV tuner built into the card. Instead you need an Infra Red emitter to send signals to your set top box whenever Myth needs to change channels.

Hardware

You can build your own serial port IR emitter very inexpensively or you can buy one.

  • MyBlaster - $45 - $50 - Reportedly very easy to set up and use. Does not use lirc. However it is a large item. Scripts for changing the channel on your box included in the Myth contrib directory. Info and purchase here.
  • irblaster.info - $12 - $15 - inexpensive serial IR blaster similar to what you might build yourself. I used this one. You stick it with included double sided tape right to the STB pointing at the STB's IR reciever.
  • DIY - with parts from Radio Shack. Wish I had a good link!


Alternative IR Blaster HOWTO

Andy's HOWTO is the easiest to follow, but is Fedora specific. It says Fedora Core 3, however I have used it on Fedora Core 4, and it should work for most Fedorae. It expects that Myth has been setup according to Jarod Wilson's Guide.

A second IR BLASTER HOWTO BROKEN LINK has been posted to HERE with a mirror at [1] This HOWTO is not Fedora specific, but requires recompiling LIRC.

If you have a Hauppauge PVR-150, it may include a built-in IR output capability. See Hauppauge PVR-150.

Installing the IR Blaster

Use the links above for detailed instructions. You will plug in the IR Blaster to a serial port on the Myth box (backend), and the other side with the diode is pointed at the STB. Normally you put it right over the STB's IR eye.

You have to load lirc_serial. There are instructions above. The way I do it on Fedora is to edit modprobe.conf. Since you likely also have an IR receiver, such as on the hauppage cards, you need two lirc modules loaded, the lirc_i2c module for the IR receiver, and lirc_serial for the IR emitter.


Configuring Myth Backend

Troubleshooting

Note that MythTV sends frequency IDs to the external channel changer script and not the channel number. If you see some weird four/five digit numbers being sent through the IR blaster, you will need to go to the channel editor in setup and change the freqid for the channels to match the ones that you expect to receive through the IR blaster.

Note: You can get MythTV 0.20 to send out channel numbers as the parameter. First, get EPG working. Then using, mythtvsetup, channel-editor, remove all your channels. To add the channels again, this time, instead of scanning for channels, get the channel list from the epg service and readd those channels.

When using the script and setup at http://losdos.dyndns.org:8080/public/mythtv-info/IR-BLASTER-HOWTO.html

  • do not* be tempted to change the configure options to set COM1/IRQ4 in the pre-make configuration. Rather, follow the directions and pass those options through /etc/modules.conf or /etc/modprobe.d/aliases.

Changing the settings at the earlier stage will produce a module that conflicts with the standard lirc (and a frustrating string of errors in dmesg: ledxmit_dev: register_chrdev failed ledxmit_serial: Unknown symbol ledxmit_register_plugin).

Alternative setup that does not require LIRC

If you prefer not to have to mess around with LIRC there are alternatives. One of these is the MyBlaster serial. (See the vendor list below.) It is a commercial product but the linux drivers are GPL. The latest driver can be found on SourceForge. To set up, simply edit the perl based driver script for your port and device and call the script using the external channel change script configuration option in mythtv-setup. It is that easy.

IR Blaster Vendors

In the USA

Mythblasterz offer an inexpensive IR blaster with 5+ meter range.

IRblaster offer serial port IR blasters, as do:

MyTVStore sells the MyBlaster products.

IguanaWorks also sell IR blasters.

In Canada

CommandIR sells a hardware-based USB multi-blaster. Available in Canada and the US.

In Europe

Dvbshop.net sell IR remotes, receivers & blasters

IRtrans sell IR transceivers (combined receiver/blaster) & LAN equipped units too

RedEyeRemote They don't look much, but these IR transmitters work via serial port with NTL PACE and Samsung STBs.

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