[mythtv-users] lirc output reliability

Robert Denier denier at umr.edu
Thu Oct 20 14:53:27 EDT 2005

I thought I saw a device that connected via a serial port that would
send remote codes awhile back, but I can't remember its name.  Basically
you would send a "2" or whatever via serial, and not the complex
modulation pattern.  The devices hardware would handle the rest.

Now, I've no idea if such a thing would work with multiple dish 301
receivers or not, but perhaps someone can at least think of the name of


On Thu, 2005-10-20 at 11:33 -0400, Dan Wilga wrote:
> At 10:08 AM -0500 10/19/05, Robert Denier wrote:
> >For some reason my lirc output has been very unreliable lately.  I keep
> >getting wrong channels, particularly sense I went to dish 301 receivers
> >from the newer model version.
> I have the same problem. I believe it has to do with the fact that 
> lirc relies on the RTC timer. If something happens to interrupt it 
> while it's pausing, the frequency of the output will be off and the 
> receiver will balk. I think what makes the 301 more sensitive to this 
> than other IR devices is the fact that it operates at a higher 
> frequency (56000 Hz) than most.
> I'm using an opto-coupler to interface my serial port to the Dish 301 
> receivers, so I know it's not an LED-related problem. I have tried 
> niceing the lirc process so it won't be as likely to get interrupted, 
> but that doesn't seem to help.
> My next step is to build a device that will send the IR pulses 
> independently of the PC, but I don't know how long that will take. 
> For now I just put up with the occasional missed program.
> By the way, I analyzed the signal received by the Dish receiver with 
> an oscilloscope and compared it to what was being generated by my 
> device. After tweaking, I came to this lirc config, modified from the 
> stock "3100" remote:
> begin remote
>    name 3100
>    bits           16
>    flags SPACE_ENC
>    eps            30
>    aeps          100
>    header        550  5830
>    one           550  1550
>    zero          550  2570
>    ptrail        550
>    gap          5530
>    min_repeat      8
>    toggle_bit      0
>    frequency    56000

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