[mythtv-users] Re: MyIRBlaster - Myth Issues Only??

[Dr. Doug L. Hoffman]

I've been using a MyBlaster with my DishTV receiver for some time now
with no problems. The receiver sometimes gets hung up, but that happens
with the hand remote as well:-) I use a Pundit and dual PVR-250s.


On Thu, 2005-10-27 at 11:41 -0400, Dan Wilga wrote:
> I have also experienced problems using LIRC to send IR signals 
> through the serial port. I believe the reason is LIRC's reliance on 
> the (low priority) RTC interrupt for timing. LIRC toggles a single 
> serial port control line up to 56,000 times per second, to directly 
> turn an LED on/off. If another thread takes control away from LIRC 
> for too long, a pulse gets stretched and the IR device becomes 
> confused.
> 
> However, this problem shouldn't affect devices like MyBlaster, 
> because its software uses standard serial I/O to send information to 
> the device. A single IR code consists of just a few bytes of data 
> sent using a slow (compared to LIRC) baud rate of 19,200 bps. The 
> MyBlaster then translates these few bytes into the many IR pulses 
> necessary to control the device.
> 
> I'm really surprised, and somewhat disappointed, to hear that even 
> MyBlasters have trouble. I was actually considering buying a 
> MyBlaster or constructing something similar on my own using a 
> microcontroller.
> 
> Maybe I'll set up a test to just send serial bytes in a predictable 
> order and see if they get garbled or missed over time while Myth is 
> displaying video.
> 
> My setup incudes a 3.0 GHz P4 running on an ASUS motherboard that use 
> the ATI chipset. So none of that matches the original poster.
> 
> I am also using a PVR-250 and a PVR-350. There's no secondary video 
> card; I'm using the onboard ATI video.
> _______________________________________________
> mythtv-users mailing list
> mythtv-users at mythtv.org
> http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users