Home > Uncategorized > Weak immune system; MythTV – getting VFD (lirc_imod) to work with serial IR receiver dongle (lirc_serial).

Weak immune system; MythTV – getting VFD (lirc_imod) to work with serial IR receiver dongle (lirc_serial).

August 1st, 2007

I think I picked up a bug from my Cousin’s live-in girlfriend when I went down to San Diego for a visit. And no, I didn’t get “close” — I’ve got a lame ass immune system and it sucks. As my brain has refused to work, I spend the day catching up on a lot of TV that I hadn’t watched, though I don’t see the point as there really aren’t many good shows on TV now-a-days. Because I was sick of using the keyboard to control my MythTV (IR receiver stopped working) I set to solve it.

Turns out it got squashed and some pins broke off on one of the components from the circuit board, as well as a break in the cable. I fixed that, and went to solving my VFD problem. Basically, the IR receiver doesn’t work if the VFD was plugged in (to USB port). I suspected that it had to do something with the order the modules were loading, and sure enough that seemed to be the case. I looked around at some way to specify the load order of kernel modules using /etc/modprobe.conf but gave up. I did discover that you could bypass the loading of a module by using the install operative. So I added this line to the file.

install lirc_imon echo foo > /dev/null

The ‘install’ command will not load the module called for, rather, it will do whatever action is at the end of the line. I’m not sure if the command is even required, but I put something innocuous there just in case. I’m not sure when lirc_serial loads, but I know that /etc/rc.d/rc.local is run last in the boot sequence, so I added these lines to that file…

modprobe –ignore-install lirc_imon
/usr/local/sbin/LCDd &

The –ignore-install flag will ignore the ‘install‘ command we added to /etc/modprobe.conf, and actually load the module. This fixed it for me. Oh, and LCDd is the server from lcdproc which MythTV uses to display text on the VFD. It is actually quite a nice implementation.


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