[mythtv-users] Hardware carrier serial blaster

Travis Tabbal travis at tabbal.net
Fri Dec 11 16:53:51 UTC 2009

On Fri, Dec 11, 2009 at 9:34 AM, Calvin Harrigan
<charriglists at bellsouth.net> wrote:
> The recent thread about the arduino blaster brought back up and idea I had a
> while back.  Are there any serial based hardware generated carrier DIY
> blasters?  One of the problems that I notice with the current serial blaster
> that I have is that during times of load channel changing fails more often.
>  I'm using the second schematic at http://www.lirc.org/transmitters.html
> It seems that the carrier might not be generated properly when the system is
> stressed.

The FTDI IR project uses an on-chip clock to deal with that. It's USB
though, not serial. It should be possible to use an oscillator for the
clock source and a logic gate to toggle the IR transmit. You would be
limited to whatever clock source you used, though I suppose you could
include a DDS chip or just use a few different oscillators. I believe
there are only a few widely used carrier frequencies.

Then you need to change LIRC to be able to pulse just the data rather
than the carrier.

More information about the mythtv-users mailing list