[mythtv-users] IR Blaster - pin 7 instead of pin 4?
Jay Littlefield
jmythtvusers at melandjay.org
Sat Nov 18 00:30:55 UTC 2006
Hello all,
I have a very strange problem affecting my MythTV system. I've searched
the archives for similar items and have not had much luck. As this is
becoming a case of spousal embarrassment, I'm hoping someone out there
can assist me. :-)
I've built a MythTV system based upon Jarod's Fedora guide.
(http://wilsonet.com/mythtv/fcmyth.php) I'm using Fedora 5 and MythTV
0.20. I have an ASUS M2NVP-VM motherboard AMD64 machine. (HDTV
outputs and Composite TV out included.) I have a PVR-150 card that is
working fine, including the IR Receiver. (The "newer grey" remote in
Jarod's description.) The system has been working absolutely fine with
local broadcast, but once I got DirecTV hooked up in my new apartment, I
have had problems trying to get the channel changing capability
working. The box is a DirecTV D11-500. This is the last item I need to
get the system so that I can do timed recordings, and I have struggled
with it for literally some weeks now.
I stumbled across Andy's site at:
http://www.eggshellskull.com/lirc/blaster/index.php. I was hopeful this
would solve the problem, so I walked through it step by step. I bought
an IR blaster from http://www.irblaster.info/ and followed the
directions on the site, downloding the RPMs from atrpms.net.
Installation went smoothly, but the blaster does not respond to the
channel changing script. I verified the IR blaster works by using the
digital camera trick while driving it from a 9V battery. (You have to
hold it REALLY close to the transmitter, but I could see it light up.)
After several days of frustration, I went onto the motherboard with a
voltmeter and measured the pins. I found that instead of using pin 4
(DTR) as the transmit pin, it is actually pin 7 (RTS) that is toggling.
When measured against pin 5 (SG), it displays a negative voltage.
(Approaximately -11V). I put Andy's change_chan.sh script in a loop to
keep the channels changing and measured the pin voltages. Pin 7's
voltage starts fluctuating. On my digital meter, it looks like it jumps
between about -9.5V and -11V. As soon as I stop, it returns to a
steady -11V. I'm quite sure this is the pin that is being controlled.
I am attempting to drive the pin using the DirecTV codes from
http://lirc.sourceforge.net/remotes/directv/G051204 in my LIRC file in
place of Andy's Motorola box codes. I'm fairly certain the
configuration is correct. It almost appears as if the lirc_serial
control is driving the incorrect pin, but I have no idea why that would be.
Every piece of documentation I have seen on ir blasters use pin 4 (DTR)
for the transmitter pin. I have downloaded the appropriate 64-bit RPMs
for all 5 LIRC components and have verified the correct kernel version
(2.6.18-1.2200). I'm wondering if there's some basic issue I am missing
with regards to this. The lirc_serial logs messages that signals are
being received. It just seems like they are being routed to a different
location.
As an alternative, I commented out the mods to rc.local and
modprobe.conf found on Andy's page and tried to implement the
configuration found on this page:
http://www.mythtv.org/wiki/index.php/Controlling_DirectTV_D11_via_USB
I had all the necessary equipment to try this, but I am running into
constant timeouts from the serial port. After multiple retries, it
simply fails. I have tried various combinations of baudrates, key
combinations, etc. After several weeks of failed efforts, I have begun
to simply blame the serial port for all failures. :-)
I'm searched the archives here and can't seem to find anything similar
to this. Does anyone have any suggestions as to why this may be
happening and what suggestions I can try to fix it? I have the Kernel
source code RPMs downloaded, but I'd really love to steer clear of
recompiling the drivers if it's at all possible.
Thanks for your help!
-- Jay
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