[mythtv-users] Serial IR Blaster Stopped Working

George Mari george_mythusers at mari1938.org
Sat Jun 28 12:25:23 UTC 2008

Richard Woelk wrote:
> Jason Sharpe wrote:
>> Hello All,
>> I am using a serial IR blaster with MythDora 5.0. I am using the 
>> blaster to control a Dish Network 301 STB which is recorded by a PVR-250.
>> Everything has been going great for a couple of years but after a 
>> reboot of my dedicated backend a couple of weeks ago the blaster seems 
>> to have stopped working with no apparent reason. (the STB still 
>> responds to the Dishnetwork remote just fine). I purchased the blaster 
>> from IRBlaster.info a couple of years ago and it includes a red led 
>> that goes off when it blasts for a visual indication of it working. 
>> The red LED no longer goes off either when it should be blasting.
>> The backend logs report no errors when changing channels for a 
>> recording and if I manually run the change_chan.sh script, no errors 
>> are reported.
>> I also try running "irsend --device=/dev/lircd 3100 1" and it doesn't 
>> report any errors, however nothing appears to be blasted either. (the 
>> STB doesn't respond and I see no Red LED)
>> So thinking that the blaster may have gone out for some reason, I 
>> ordered a new serial ir blaster from IRBlaster.info however the new 
>> one has the same exact problem.
>> I am not sure what else to try.
>> I see there is a newer version of lirc out (0.8.4) but I wasn't sure 
>> if upgrading would fix it or not.
>> Anyone have any ideas on what else to check to try to resolve the issue?
>> I guess my serial port on the motherboard could have just gone bad. 
>> Does anyone know if a USB to Serial adapter will work with lirc and a 
>> blaster?
>> Some info:
>> *****************************************************
>> [mythtv at mythtv ~]$ lsmod | grep lirc
>> lirc_serial                       16020       0
>> lirc_dev                          15044       1 lirc_serial
>> ******************************************************
>> ******************************************************
>> [mythtv at mythtv ~]$ yum info lirc
>> Installed Packages:
>> Name  : lirc
>> Arch    : i386
>> Version: 0.8.3
>> Release: 74_cvs200080314.fc8
>> Size: 1.5M
>> Repo:  installed
>> *******************************************************
>> *******************************************************
>> [mythtv at mythtv ~]$ vi /etc/rc.d/rc.local
>> #!/bin/bash
>> # This file allows you to execute things at the end of boot
>> touch /var/lock/subsys/local
>> #IRBlaster
>> setserial /dev/ttyS0 uart none
>> /sbin/modprobe lirc_serial type=0 irq=4 io=0x3f8 softcarrier=1
>> /usr/sbin/lircd --device=/dev/lirc0 --output=/dev/lircd
>> /usr/sbin/lircd --driver=default --device=/dev/lirc1 
>> --output=/dev/lircd1 --pidfile=/var/run/lircd1.pid
>> ***********************************************************
>> I have tried both COM1 and COM2 in the rc.local and I again get the 
>> same results, nothing appears to be blasted, but no errors.
>> In all my testing I have never once gotten an error from my Mythtv 
>> box, either in logs or with me manually running commands.
>> I am also open to just getting a new USB Blaster if that is an easy 
>> way to solve this, can anyone recommend one?
>> Thanks for any help you can provide.
>> Jason Sharpe
> Do you have an IR receiver on the same serial port? You could test the 
> driver with mode2 and aim a remote at it. (make sure lircd is not 
> running) If it spits out numbers, it will tell you if the driver has 
> loaded properly and it is working.
> Using a USB to serial adapter usually won't work with LIRC. The LIRC 
> device uses the serial port in a non-standard way, a USB device can't 
> toggle the handshake lines quick enough or with the right timing. I 
> think a PCI serial card should work though I haven't tried one.

You can test if your serial port has gone bad or not by temporarily 
connecting a serial modem to it, if you have one or can borrow one.  If 
you can use a terminal program to 'talk' to the modem, then the serial 
port is obviously good.

Or, if you have another Linux box with a serial port, temporarily setup 
your hardware and lirc config on that, just to see if your IR hardware 

I've blown out several serial ports on my remote front end - it sits in 
the basement and cables for video, audio and serial IR receiver lead 
upstairs to the TV in the family room.  What I found is that the long 
cable for the IR receiver connected to the serial port (about 25 feet / 
8 meters long) was susceptible to static, especially during 
thunderstorms we get here in the Midwest).  I've since added serial port 
surge protectors on both ends of the cable, and all has been well.

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