[mythtv-users] lirc output reliability
Dan Wilga
dwilga at MtHolyoke.edu
Thu Oct 20 11:33:12 EDT 2005
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
--
Dan Wilga dwilga at mtholyoke.edu
Web Administrator http://www.mtholyoke.edu
Mount Holyoke College Tel: 413-538-3027
South Hadley, MA 01075 "Who left the cake out in the rain?"
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