[mythtv-users] Gave up IR Blaster ordered MyBlaster

Robert Denier denier at umr.edu
Sat Nov 5 04:44:09 EST 2005

I finally gave up on an IR Blaster.  I tinkered with the gap various
times and never found a value that was rock solid with Dish Network
receivers.  If I had a remote receiver that would see the 56k pulses It
might help, in that I could get the value of gap that way, which may or
may be enough help.

>From what I can tell there are two problems with generic IR blasters.

1) The faster modulation frequency required makes it that much harder to
be consistently right and not mess up any channel changes.

2) Kernels these days hapilly multithread, and it is so easy for another
process to delay things and mess up the timing.  Maybe if the entire
blaster code was in the kernel, it might be able to remain solid
regardless.  I'm not sure if a kernel scheduler is available to insure
the precision needed to gaurantee this.  Even if it was, it would
probably be a lot of work to figure it out, and would probably take a
decent chunk of resources just for that task.

What is needed almost is to find an external interface that runs at
56kHz.  I can't see how using the data lines on a serial port can work
cleanly since you have the start and stop bits..  

Something like one of national instruments digital I/O boards would
likely be simple enough to program to do it, but then it is cheaper to
buy the my blaster.  Similarly you could develop something similar to
the myblaster, but then it is again easier just to buy the MyBlaster
product since the time involved, for me to do it anyway, would not be
trivial..  This might be something to think of if I ever get back to
working on figuring out USB chips with microcontrollers.. If nothing
else it would be a good learning project..

At any rate, as the title suggests, I basically gave up on getting an IR
blaster to work solidly in my case with Dish Network receivers.  I
suppose if you dedicated a machine just to that, it might work, since
there would be no large programs preempting things, but with myth doing
everything else, it just seems unlikely in my case..

I'll let everyone know my experiences with the MyBlaster in a week or
two, once I've had time to get it and be sure of it..

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