Sunday, May 18, 2008

The TiVo finally died

As the subtitle of this website mentions, part of my mythtv journey has been getting my wife to give up the TiVo in favor of the mythbox. After several years of resistance, I finally started to really win her over one we got our new HDTV. In the 2 months since then, she stayed pretty clear of the TiVo. She went back briefly on a few occasions when the mythbox failed to record something. However, even that occasional problem has been solved now that she knows she can just get the episode via a torrent.

She's been 100% TiVo free for over a month now. Things have been going so good, I was just about getting ready to pull the plug on the TiVo permanently. However, yesterday the issue was forced...the TiVo no longer functions. It's failing to pass through any signal via the coax or ouput anything on the composite output. The system powers up, the drive spins, but nothing happens. I just get a blank screen.

The TiVo functioned for a good 4.5 years, so at least I feel I've gotten good use out of it. I'm just glad I was able to get her to make the transition on her own terms, rather than having the thing yanked out from under her. The mythbox was able to win on its merits, rather than by default. here to read more!

Tuesday, April 29, 2008

MythTV iMON server - alpha release 1

As I mentioned before, I've been working on an LCD server for mythtv in my spare time with the intention of making full use of the iMON LCD's icons. I'm happy to say that I'm ready to release the first alpha version. Its a little rough around the edges, and very basic in functionality at the moment, but it's a decent start.

Note: this application is specifically for the iMON LCD...NOT the VFD. If your display doesn't look like the photos at the bottom of this page, you have the VFD, and this program won't do you a bit of good.

How to get it
First, you will need to download 2 separate archives. The first is the application specific archive, and the second is an archive of perl libraries I've written.



Make sure the RFLibs folder exists as a subdirectory of the folder where you put the mythimon files.

Running it

The first thing you want to do is to disable any other software that is outputting to the lcd (including LCDproc). The only thing you want to keep loaded is the lirc imon lcd driver.

Next, the simpler test is to try running and make sure you get output on the LCD. If you have the older version of the iMON LCD, you will need to edit the code and change '15c2:0038' to '15c2:ffdc'. Also, if your device is setup somewhere besides /dev/lcd0, modify that setting too. If it works, you are good to go for the next test. If not, check for things like perl libraries, and make sure you are using at least perl 5.8 (needed for the thread support).

Next, you can try the application. First you need to open it up and setup a few config variables. Specifically, the port numbers for the lcd server and the network control, the location of the frontend log file, the location of the lcd devices, and the iMON version.

If you don't have logging enabled for your frontend, you will need to add logging by adding the necessary paramters to the script that launches mythfrontend (ex "-l /var/log/mythtv/mythfrontend.log"). You will also need to have enabled both the network control port (found under setup->general) and the lcd port (under setup->appearance). You may need to restart the frontend for these changes to take effect.

Once that's all setup, you want to kill the existing instance of the mythlcdserver (so you can steal the port from it) and quickly start up the application. You can do this with the command:

killall mythlcdserver; ./

You should now be looking at a screen with a clock. Next, you need to wait up to 10 seconds for mythfrontend to connect to the lcdserver port. When it does, you will see the output "FIRST COMMAND RECIEVED FROM MYTHLCDSERVER" appear on the command line (not on the LCD).

Now, when you go to watch TV or listen to music, you should get info on the screen and icons lit up. If not, again, check for perl libraries. Make sure you have the mythtv perl bindings installed.

Known Limitations

Being a work in progress, there is (by definition) a lot of stuff to be added or improved upon. Here are some of the known limitations, and what I plan to do:

Menu Support - This will be added most likely in the next version. I plan to integrate it with the front panel controls of the case via lirc. This way the menu's won't pop up whenever there is a menu change in myth (as mythlcdserver does). Instead, it won't display the menus until you hit the specified button on the front panel to enter menu mode. Then the menu display will override everything else until you hit the specified exit key or you let the menu timeout.

Volume Support - This will be added eventually. I plan to add a bit of configurability here...perhaps with plugin modules. One of the things I want to do for my specific setup is to integrate it with my TV, so it controls the volume via the serial port. I prefer this to adjusting the volume within mythtv. However, that's not going to work for most people, so I'll make it work both ways. With a simple plugin architecture, I'm thinking people could customize it to work with their setup (such as controlling an AV receiver).

Generic Info - This is info like photo names in the photo gallery, etc. Hopefully this will be in the next verison also.

Pausing/Stopping - There are times when myth doesn't send progress updates (like when playing music in the background). As a result, I've taken it upon myself to continuing calculating the progress on the assumption that playback is proceeding as normal. However, since myth sends no pause events, I have no way to track them. Thus, when you pause, my script doesn't know it, and keeps going. A similar problem exists with not knowing when music playback has stopped. I haven't yet figured out an ideal way to handle this. Probably some hack of monitoring the IR codes, cross reference that will the current location as reported by the network control port, etc.

Ideas for future expansion

I welcome feedback on ideas for what other types of things to do. There are some things I'm not sure about:

Uses for icons/display features - Anything interesting I can do with the top progress bar, other than just duplicating the bottom progress bar? When I add menu support at a later time, I was thinking I could use it to track progress through the menu (like a scrollbar on the side of your browser). How about the spinning disk, and the tray icon right below it? And the vol and time icons (one use is obvious, but also kind of pointless)? How about the source icons? I've taken advantage of TV and HDTV, but not SRC/SRC1/SRC2/FIT (and while we are at it...what the heck is FIT for anyway?).

Any good way to get the recording status out of the backend for the rec icon? I could also try monitoring the backend log, but that won't always be available on the remote frontend.

Anyone know a way to get codec data out of the music player to light up those icons?

How about getting weather data out of mythweather?

Is there any easy way to get spectrum analyzer data out of myth or the linux audio system?

Custom Fonts

I've created 2 different fonts for the application. The first is a normal font, 16 pixel tall (currently used for the clock). The other is an 8 pixel tall font with small caps instead of lowercase letters. OK...technically I made a 3rd font, but it only consists of 1 charachter (space), and is only meant as a vertical spacer in the display.

If you would like to make your own fonts, you can use this utility

If you come up with some good fonts, please feel free to share them with me.


 here to read more!

Tuesday, April 22, 2008

Developng an iMON client for MythTV

Over the last few weeks I haven't posted anything here. I've been using whatever time I could to work on developing an iMON client that can interface with MythTV. I've been making some decent process, and although I have a lot of features I still want to implement, I think I might be ready to release a limited-functionality alpha version in a few days. For now, I just want to discuss why I'm developing it and what it has to offer over the standard mythlcdserver.

Why not use mythlcdserver

The iMON LCD device has a lot of new capabilities. It's not just a standard 16x2 (or whatever) text display. It goes way beyond that. It's actually a 96x16 pixel display (1-bit each). In addition to displaying text, it can display arbitrary graphics. This gives it a lot of options. You can use custom bitmapped fonts of any size. You can draw symbols on the display. Really, anything you can imagine. The only real limitation (other than size and bit depth) is that, like a lot of inexpensive LCDs, the response time is a bit slow, so animations don't work well (it kind of blurs together).

In addition, the iMON also supports custom icons. You can turn on icons for different a/v formats (mp3, divx, dts, etc), icons to represent the number of audio channel, and a bunch of others.

These sort of features are completely absent from mythlcdserver. They aren't something that would work with a small tweak. They would require a complete overhaul of the application. It would also require some changes to the way myth itself works, since currently myth doesn't provide any of this data to mythlcdserver. In the end, it would be a huge change, which presents 2 obstacles. First, getting a change that major into myth would be a bit difficult (I've had significantly smaller changes in there for months without anybody accepting/rejecting or even commenting on it). The second is that, even if it were to get included, it would require a myth recompile for people, or would make people wait until the changes made it into the next release of mythtv (or mythbuntu, knoppmyth, etc).

In summary, it just seemed to me to be better to do it in a new application.

What cool things can be done?

The first obvious thing that can be done is to support the iMON's 40+ icons. The next thing you can do is to use the 4 horizontal lines as progress bars, instead of wasting an entire row of the display on the progress bar. This gives you more space for display info while still having the progress bar visible at all times.

As I already mentioned, the bitmapped LCD gives a lot of options for bitmapped fonts. Not only can you do half height text (8 pixel) or full height (16 pixel), but you can do any size you want. Perhaps a slightly bigger 11 pixel font on top and a tiny 5 pixel font on the bottom. Or instead of the 5 pixel font, you can display icons across the bottom for the functionality of the front panel buttons (pause, rewind, etc).

How does it get the data

The correct way to get the data would be explicitly from myth. However, as I already stated, this data isn't readily available, and making it available would require a wide range of modifications to mythtv. Instead, I'm going the quick and dirty route. I collect the data from a variety of sources. I pretend to be the mythlcdserver program and monitor port 6545. I scrape data from log files. I gather data from the network control on port 6546. I watch for IR commands. I then weave all of this data together to get a coherent picture of what is going on in myth. It's not 100% perfect, but it works well enough to make me happy. here to read more!

Saturday, April 5, 2008

Getting iMON 0038 LCD working with LCDproc

Yesterday I discussed how to get the iMON display working in LIRC. The next step after that is to get the LCD display working. The most popular program for controlling the LCD is probably LCDproc. As it turns out, once you've got LIRC running the LCD properly, it's relatively easy to get LCDproc going too.

Once again, these instructions are specific to the 0038 version of the iMON LCD. Other versions may need slightly different instruction. Check over at the forums for details.

Step 1 - Making sure your LIRC installation is good

LCDproc relies on the lirc_imon driver that is part of LIRC. If that isn't properly configured and installed, you have little hope of getting LCDproc going. Well, I've heard it's possible to have LCDproc control the LCD directly without LIRC, but I haven't tried it so I don't know if it's true, and even if you were to do so you'd lose its IR and front panel button capabilities. For this reason, LIRC is really the right way to go.

To test if your LIRC installation is correct, you can run the following command:

perl -e 'print pack "H*", "80000000091e0088"' > /dev/lcd0

When you run this command you should see the LCD clear itself and then display a clock with the time "AM 09:30" (in an ugly font, where the 4's look like 9's, and are only different by a single pixel, but I digress). If that's what you get, then lirc_imon is configured fine. You can proceed to step 2 after resetting the LCD with the following command:

perl -e 'print pack "H*", "4000000000000088"' > /dev/lcd0

If you weren't so lucky, then you might have a problem. First thing you want to do is make sure the driver is loaded:

lsmod | grep lirc_imon

You should get back a few lines of text that contain the lirc_imon driver and some other drivers (lirc_dev, usbcore, etc). If you get back nothing, try loading the driver manually:

modprobe lirc_imon

Then try running the command to set the clock again. If it works now, you may need to find a way to load the lirc_imon driver automatically (possibly by putting lirc_imon in /etc/modules). After that, you can proceed to step 2 (turn off the clock, first).

If it STILL isn't working, go back again and test whether the iMONs IR and/or front panel buttons are still working with LIRC. If not, somehow you don't have LIRC built correctly, with the correct patches, so you need to fix that first. Check out yesterday's post on that topic. However, if it does work, then my best guess is that LIRC thinks you have the VFD rather than the LCD and built the lirc_imon module for that device.

If you configured LIRC for only a single device (the Soundgraph iMON IR/LCD), then it should have handled everything for you. However, if you are like me, and have a separate IR receiver that you are using, and thus need to install LIRC with multiple drivers, you probably configured it something like:

./configure --with-driver=all

As I covered in an update to my post on setting up LIRC with multiple devices, the --with-driver=all option will configure it to use the VFD rather than the LCD. You will need to change config.h so that the line:
/* #undef LIRC_IMON_LCD */

#define LIRC_IMON_LCD 1

and then recompile and reinstall LIRC. Then unload and reload the lirc_imon driver. Then once again try the perl command to set the clock. It should now work (once again, be sure to turn off the clock before proceeding). If you still have problems...I have no clue. You are on your own. Try posting over at the forums.

Step 2 - Configuring LCDproc

This is actually a much simpler process than it was configuring lirc. Once again, you will want to follow the basic instructions post by Dean at the forums. However, you will want to make the following changes.

1) Instead of using dean's lcdproc-0.5.2-imonlcd-0.3.patch patch, download my slightly modified version. I've made a few tweaks where he forgot to set an icon flag or set the wrong icon flag.

2) After running automake but before running configure, you will want to download my slightly modified version of madCoder's patch for the 0038 model, and apply it by running

patch -p1 <../lcdproc-imon_0038-v2.patch

3) When you get to the part about modifying the /usr/local/etc/LCDd.conf file, rather than changing the file manually, you might want to start by downloading my patch for the conf file and applying it with:

patch /usr/local/etc/LCDd.conf ../LCDd.conf.patch

This saves you from the error prone process of modifying it manually, especially since it's easy to leave off the leading or trailing slash on the DriverPath setting (in fact, deans instructions even left off the trailing slash).

4) Dean mentions changing the RENDER_FREQ from 8 to 1. You might want to experiment with other values in between (2 to 4). While I found 8 to be too fast, 1 update per second was too slow for my tastes. If you decide to play around with it, you will need to recompile each time (it would be better to move this to the config file, but I didn't find it important enough to waste the effort on). After making a change, you do NOT need to rerun configure or any of the previous commands. Just make and make install.

Step 3 - Testing LCDproc

This part is quite easy. Just run the following command:

LCDd -f -r 4

The display should light up with some text from LCDproc. If not...well, I really don't know what could have went wrong. Just make sure you carefully followed all of the instructions in the proper order (are you sure you ran the command to turn off the clock in step 1)?

Thats it!

See, it was quite easy. In fact, if you take a look at my instructions, you'll see that there was more detail involved with debugging your lirc_imon setup than there actually was getting LCDproc going.

You can now go on to configure your other applications to interface with LCDproc. Sorry, I have no advice on that part yet. I'm actually working on my own interface program at the moment (it seems I've got more things going on than I have time to write about). I'm sure I'll talk about that at some point. here to read more!

Friday, April 4, 2008

Getting iMON 0038 LCD working with LIRC

As I mentioned before, getting the iMON display working was a bit troublesome. However, I managed to get it all working. Since it was so problematic, I'd like to share details of how I did it.

Before continuing on, I have to give huge thank you to Dean Harding for setting up the forums and for all the work he did with the iMON. Also, thanks to many of the people in those forums who provided followup info and helped troubleshoot/patch things to work with newer versions of the hardware (especially madCoder for his patch for the 0038 model).

Also, I just want to say that, while the following instructions may seem a bit long, it really doesn't take that much work. A lot of this will just be verbose text. I'm trying to provide as thorough instructions as possible and describe whats going on, so that if you run into problems (ex: your configuration is a bit different), hopefully you will understand what needs to be done and figure out how to work around it.

Step 1 - Determine which version of the iMON you have

First, you need to get the ID of your iMON device. Run the lsusb command and look for a line that says Soundgraph. Before that will be the ID string. In my case, it's 15c2:0038, with the 15c2 being the vendor ID and the 0038 the product ID. If this is the version you have, then the rest of the instructions on this page should hopefully get you up and running.

If you have the 15c2:ffdc version, you have the original, and you can probably just follow Deans instructions from If you have another version number, then that means either Soundgraph has changed the device again, or you don't actually have the LCD (perhaps you have the VFD, which is a very different device). In either case, you can have a look around at the forums and see someone has figured it out.

Step 2 - Determine if usbhid is controlling the iMON

Originally, the instruction I found for setting up the iMON display didn't work. I followed them to the letter, but had no luck. Well, as it turns out, it seems newer versions of the kernel (I'm running Debian 2.6.24) have support for the iMON in the usbhid driver. That means when the usbhid driver starts, it takes control of the iMON. Later, when the lirc_imon module loads, it's unable to take over the device.

So the first step necessary in setting up the iMON is to make sure the usbhid driver hasn't taken control of it. Run "cat /proc/bus/usb/devices". The output of this will be 1 block of info for each USB device in on the system. You want to find the block(s) that has Vendor=152c and ProdID=0038. Then look down a few lines further in the block and look for the line that contains "Driver=". That will tell you what driver is loaded for that device. If the driver is "usbhid", you need to continue on to disable it. If it's "(none)", you can just skip step 3. If you see lirc_imon, then you already have the proper driver loaded. Anything else and you are on your own.

Edit: It has come to my attention that /proc/bus/usb/devices doesn't exist on all systems. Apparently not every distribution has usbfs mounted. You can run the command

mount -t usbfs none /proc/bus/usb

to mount it, and then /proc/bus/usb/devices should exist.

Step 3 - Prevent usbhid from controlling the iMON

Assuming the usbhid driver has been loaded, you now need to disable that. You probably don't want to completely disable the usbhid driver, because that can prevent other devices from working properly (such as usb keyboards and mice). Instead, you want to tell the driver to ignore your particular device. The following instruction work for the 2.6.24 kernel under Debian.

1) Edit /etc/modprobe.d/usbhid (create it if it doesn't exist) and add the following line. The first hex code is the vendor ID, the second is the product ID, and the 0x0004 means ignore this device.

options usbhid quirks=0x15c2:0x0038:0x0004

2) Run the command: depmod -ae
3) You need to rebuild your initrd. If you are running a typical installation, you can do this by running:

update-initramfs -u

In my case, I'm doing a diskless boot over NFS, so I had to do it slightly different. Edit /etc/initramfs-tools/initramfs.conf and make sure BOOT is set to nfs. The run "mkinitramfs -o initrd.img.netboot". Finally, copy the new initrd.img.netboot over to the appropriate location on the tftp boot server (and rename it if you are using a different filename in your setup).

Once this is all done, a reboot should use the new settings and stop loading usbhid for your iMON. Run the "cat /proc/bus/usb/devices" once again. This time, the driver should be listed as (none). If it is still usbhid, do NOT continue on with these instruction until you've figured out how to deal with it for your particular distribution.

Step 4 - Installing LIRC

The basic installation instruction come from this post in the forums. The patches to deal with the 0038 model come courtesy of this post by madCoder. In addition, I've made a few small changes to the patch to deal with the iMON pad remote and the front panel buttons on the Thermaltake DH-101 case. Other cases with front panel buttons likely require this same patch. If you don't have this case, I don't really see any harm in using my patch anyway.

You can get detailed info from the above 2 posts, but I'll summarize it below to help you keep things in order between both posts. Also, I'll provide links to actual patch files you can download, because copying and pasting the patch files from the forum are likely to get you "malformed patch" errors because of formatting issues.

Also, before beginning, you'll want to make sure you don't already have an installation of LIRC by running "apt-get remove lirc"

1) Make sure you have the prerequisites for LIRC installed as listed on this page. In my case, I was able to do that through apt-get:

apt-get install libtool automake1.9 autoconf

2) Download the current version of LIRC from CVS.


With the latest version of lirc (as of sometime in early 2009) all the necessary patches have been included into the CVS version of lirc. It is now possible to get full iMon support without applying any patches to the CVS branch (at least until SoundGraph decides to create a new iMon device with different control codes :)

Anyway, I'm crossing out the info that is no longer needed (but I'm leaving it here in case anyone has any use for it)

The 0038 version of the iMON hardware requires you to patch the LIRC code first. Download this patch and then install it by running the following command from within your LIRC directory:

patch -p1 < lirc-imon_0038-v2.patch


The code in CVS has changed slightly, and a critical part of the patch no longer applies automatically. Until I get a chance to update the patch, you will need to do the following AFTER applying the patch:

  1. Edit drivers/lirc_imon/lirc_imon.c

  2. Find this line:

    { USB_DEVICE(0x15c2, 0xffdc) },

  3. Add this line after it:

    { USB_DEVICE(0x15c2, 0x0038) }, /* IR & LCD */

Then you can continue with the next step


It looks like cvs has been updated to handle the new version of the imon. However, from what I've heard, it appears that the patch applied to cvs wasn't as comprehensive as the patch I applied, and some of the buttons on the pad remote as well as some of the case front panel buttons might not work.

I haven't yet had a chance to look at the new version to see what it takes to get it going. In the mean time, if you would like to try with the old version from CVS, you can download the version I used from:

4) Run and This will give you the configuration dialog. Choose the following sequence:

Driver Configuration -> USB Devices -> Soundgraph iMON IR/LCD

Save configuration & run configure

5) Run make, make install, and then modprobe lirc_imon.

With the 0038 version, you should have devices setup for /dev/lcd0, /dev/lcd1, /dev/lirc0, and /dev/lirc1. In addition, you are also going to have a device for /dev/lirc, but thats not really important. The actual devices we need are lirc0 and lirc1.

Notice to Ubuntu users: I received an email from Sascha Zucca who said that after following these instructions, he did not get all of the appropriate devices showing up under /dev. After working through the problem with him, he discovered that Ubuntu was loading its modules from a different directory than the lirc installer was putting the compiled files in. As a result, even after installing the new modules, lirc was loading the old version without the iMON fixes. Here is how he told me he fixed it:

i had to
mv /lib/modules/2.6.24-16-generic/ubuntu/media/lirc/lirc_imon/lirc_imon.ko{,.OLD}
ln -s /lib/modules/2.6.24-16-generic/misc/lirc_imon.ko /lib/modules/2.6.24-16-generic/ubuntu/media/lirc/lirc_imon/

I've since received a half dozen emails from other users who encountered the same problem. Performing the same fix worked for each of them (taking into account that the path will be slightly different for different versions of Ubuntu). Also, take note of the line wrapping. Those are actually only 2 commands.

FYI - Why are there 2 LIRC devices?

The iMON pad remote acts like a mouse/keyboard in addition to a remote. In the old version, it was my understanding that this was all handled through one LIRC device. However, the 0038 version splits it into 2 devices. All of the mouse/keyboard related keys come through the lirc0 device (the directional pad, left click, enter, the number button, ect....however NOT including the Mouse/Keyboard toggle button). Everything else comes through the lirc1 device (play, eject, colored buttons, zoom, the Mouse/Keyboard toggle button). Finally, if you have front panel button, they will also come through the lirc1 device (at least they do on the DH-101).

If you have no plans to use the included remote, and plan to use a separate LIRC receiver with a different remote, you might think you can just skip the lirc0 part and use lirc1 for the front panel buttons. However, that may not work. Even if you don't use the iMON's IR receiver, it will still pick up some of the IR signals from certain remotes. When it does you will run into a problem. The iMON buffers up the inputs from each device separately, but maintains the sequence of events between the 2 buffers. If you only run the lirc1 device, everything will work fine until the iMON picks up an IR signal that it decides to put in the lirc0 buffer. When that happens, the lirc1 buffer will appear to have locked up and will not generate any more events. In reality, it's just maintaining the event sequence, and the next event is waiting to be removed from the lirc0 device. Until you do that, you will see no more events coming from the lirc1 device.

Now, on to the testing.

Step 5 - Testing and using LIRC

First you are going to need a lircd.conf file. For the pad remote, you can download this file. For the Thermaltake DH-101, you can download this file. If you want to use them both, you can just combine them into the same file. Whichever file you use (or both files combined), you will need to put that file in /etc/lircd.conf.

Once lircd.conf is in place, you can do the actual testing of LIRC. You need to get both devices up and running. The way to do this it to run 2 copies of lircd. The first one needs to listen to a socket and output its events there. The second one connects to the remote socket, gets events from there, and combines those with its own events. Each of the 2 processes will be listening to a different iMON device. Run the following 2 commands:

/usr/local/sbin/lircd --driver=default --device=/dev/lirc0 --pidfile=/var/run/ --listen=8765
/usr/local/sbin/lircd --driver=default --device=/dev/lirc1 --pidfile=/var/run/ --output=/dev/lircd --connect=localhost:8765

Now you can run the irw program and start pressing buttons on the remote and/or front panel, and you should see the event output on the screen. If you have a different case and don't get output from the front panel buttons, you will need to record a custom configuration file for it using irrecord.

First, you need to kill off the lircd processes (kill `pidof lircd`). Then you need to run irrecrd, but you need to point it at the right LIRC device:

irrecord --device=/dev/lirc1 frontpanel-lircd.conf

Follow the instructions to create your config file. When it's done, you will want to add the contents of frontpanel-lircd.conf to your /etc/lircd.conf file. Then restart both lircd processes and try irw again. Everything should be fine (hopefully)


If you made it this far, then you must have got everything working. Now you probably want to do something useful with the LCD. The most common program to control it is LCDproc. I've covered getting LCDproc setup with the iMON in this post.

If you have any questions or problems, be sure to leave a post in the comments below, or email me (you can find my email address through the "My MythTV Patches & Add-ons" link at the top of the right hand column). Or you can post about it in the iMON forum over at here to read more!

Wednesday, April 2, 2008

Setting up LIRC with multiple devices

In the process of building my latest mythbox, I've been doing a lot of adhoc experiments with a various things over the last few weeks. I thought it was time I start putting some of them together to start moving towards a working system. One of those things I needed to do was get all 3 of my lirc devices working together. The process turned out to be a bit trickier than I expected, but I got it done, and thought I'd share the details of a couple of the trickier spots

Why three lirc devices?

I wish I could say I only needs one device, but unfortunately that's not the case. First of all, my new Thermaltake DH-101 case has a set of front panel buttons, and the driver handles those buttons by treating them like IR codes and sending them through LIRC. I certainly would like those buttons to work, so that's one device.

In addition, as I discovered in my driver writing experiment, the iMON (which handles the front panel buttons) will block the input queue if it receives certain IR signals. The only way to unblock it is to remove those signal events from the queue, and the way that gets done is by exposing a second lirc interface. So, I need to have that interface working if I want my front panel buttons to continue working.

Finally, since the iMON can only receive a very limited subset of IR signals, it is pretty much worthless as a general purpose IR receiver. Therefore, I have a separate receiver...the IRA-3 (which appears to lirc as an Irman).

Compiling LIRC to support both drivers

The 2 iMON interfaces use the lirc_imon kernel driver (via the lirc default driver), while the IRA-3 uses the irman driver. Therefor, I need to get both drivers installed. However, thats one are where lirc is a bit troublesome.

The suggested approach is to configure/make/install lirc once for each individual driver, and then configure again with the --with-driver=all flag. This will configure lirc to make and install every supported lirc driver available. That's not exactly ideal, but it works. However, when I tried that, I got errors during the build complaining the the necessary bttv libraries were not installed and it couldn't continue. Now, it seemed silly to have to install dependancies for drivers I never even planned to use, so I was determined to find a better way.

I tried every way I could think of to run configure: with individual --with-driver parameters (one for each driver), as well as using a single flag and specifying both drivers (space separated, comma separated, quoted, etc). Nothing I could come up with would work. After searching and finding no resolution, I started trying to hack the configure script (which got me nowhere). However, I eventually found a trick that worked...hack the generated makefile.

The trick here was to configure it with --with-driver=all, and then edit the drivers/Makefile script. In here, there are 3 parameters to be edited. Each parameter contains a list of all the lirc drivers. You want to remove any drivers from that list you aren't interested in. The three parameters in that file you want to edit are: lirc_driver, DIST_SUBDIRS, and SUBDIRS. Once you've modified those lines to remove the extra drivers, just run the make and make install.

Edit: Well, a few days later, I get to work trying to setup my lcd display and realize it's not working. It seems that compiling lirc for all drivers makes it pick and choose between some mutually exclusive settings. One of those setting was whether the lirc_imon driver is built for the LCD or the VFD. It picks the VFD. In order to fix this for the iMON LCD, after running configure you need to edit the config.h file (in addition to the drivers/Makefile). Change config.h so that the line:
/* #undef LIRC_IMON_LCD */

#define LIRC_IMON_LCD 1

Then continue on with the make and install. You may find a similar issue occurs with some of the other hardware.

Getting all 3 devices working

Now that I had lirc installed with all the drivers, I needed to get the 3 lirc devices functions. First steps was to test them out individually using irw and then merge them together. Unfortunately, I had an odd bug which I was able to resolve, but can't explain. My lircd.conf file has definitions for 4 remotes (my hauppauge remote, my wife's tivo remote, the iMON Pad's IR codes, and the case's front panel butons). For some reason, the Tivo/Hauppauge remotes would work no matter which order they were in, but the, but the other 2 wouldn't work with the TiVo and hauppage remotes defined first. I had to switch the order to get all 4 to work.

As far as I can tell, they are all valid definitions, and they all work. I was able to pinpoint the problem more specifically. If the earlier definition had the post_data_bits attribute definited, the iMON and front panel button definitions failed to work. Commenting it out fixed the problem with the lower definition (though it broke that one). Curiously enough, each of the 4 definitions has a post_data_bits attribute set, yet they all work fine when in the correct order. I can't seem to make sense of it.

Getting them working together

Now that I had each one working individually, I needed to get them working together through a single interface. I found documentation specifying how to use the listen and connect parameters to connect multiple lircd instances together. I tested, and that worked well enough for 2. However, as soon as I added the third, only one of the 3 would work.

It turns out that lircd has its client/server model a bit different that what I'd expect and would believe is the normal way to do it. Normally, when you have multiple processes connected together by sockets, you have one server that listens on the port and then multiple clients that connect to the one socket. And indeed, if you attempt this with lirc, it works perfectly. The one server will happily establish connections with multiple clients, but it won't actually do anything.

Instead, what you need to do is have all but 1 instance of lircd running as a server (ie: listening), and then have a single client connect to all of the servers, aggregate their data, and output it all on the single interface. Once I figured that out, it worked like a charm.

Just for reference, in case you'd like to see the actual commands I used:

lircd --driver=irman --device=/dev/lirc --pidfile=/var/run/ --listen=9988

lircd --driver=default --device=/dev/lirc1 --pidfile=/var/run/ --listen=9987

lircd --driver=default --device=/dev/lirc0 --output=/dev/lircd --pidfile=/var/run/ --connect=localhost:9988 --connect=localhost:9987 here to read more!

Sunday, March 30, 2008

Writing my first linux driver - Part 1

I've always wanted to write a driver for a piece of hardware, but hadn't the slightest clue how to go about it. It seems like such a complex process...interfacing with the system at the kernel level, dealing with the necessary subsystems (ex: USB), reverse engineering the device's communication protocol. Where does a driver writing noob even begin?

Getting my inspiration

Luckily, I found a very insightful and well written series of articles by Greg Kroah-Hartman, who is the official maintainer of (among other things) the linux USB subsystem code. In his series, he covers all kinds of topics dealing with driver writing. Theres a lot of content, and it's not exactly laid out in step-by-step tutorial form. Still, it is by far the best resource out there that I've seen so far.

A list of the articles is located here. Lots of those articles are useful, but the most enlightening for someone getting started were the articles on writng usb drivers, writing your first kernel space driver, then rewriting the driver as a user space driver. In addition, the article on snooping the usb stream was helpful in figuring out how to reverse engineer a devices protocol from the working Windows driver that almost every usb device has.

Choosing a device for my first driver

So now that the series of articles had inspired me, I needed a piece of hardware to serve as my first driver. I quickly figured out a way to kill 2 birds with one stone.

I've been having some success getting my LCD working, but I've been having some trouble with the IR part of it. It seems that when the IR sensor receives certain signals, it locks up and stops responding. However, it works fine under Windows, so theres some issue in the current linux driver for this device.

The device seemed to be simple enough. I didn't envision a lot of back and forth communication. I envision a one way stream of incoming data for the IR sensor, and another of outgoing data to write to the LCD. The hardware didn't appear to have a lot of conditional states built into it. That meant there probably woulnd't be a lot of tricky reverse engineering such as "this command does X if the device is doing A, but Y if it's doing C, or Z if it's doing C or D" etc. appeared it would (hopefully) be fairly straight forward.

Reverse engineering the protocol

If I needed to, I could always try to strip some protocol information out of the existing partially working driver. However, I figured it would be best to start out from scratch (that would be the most rewarding experience for my learning process).

I downloaded a copy the Snoopy program for Windows, hooked the LCD up to my Windows system, installed the drivers, and started monitoring the stream with Snoopy. Snoopy has it's pluses and minuses. It's very simple to use, but it doesn't let you monitor the stream in real time. It records it all to a log file, which you can later look through. The entries are all timestamped (relative to the start of the log), so you can tell what happened and when.

So first thing I did way was start up the log and watch the event counter grow. After a couple seconds, the counter stopped. I waited 10 second and the count remained steady. Great...that means I can look at that bunch and treat it as the initialization code. I then pressed a single button, waited for the event counter to stabilize, and then waited another 10. Then I started doing the same with other things (turn the volume knob, hit the menu key, switch the driver into graphic eq mode, etc).

At the same time I was doing this, I was writing down on paper a list of what actions I took at each step, and what type of feedback I got for each action (text on the LCD changed, an icon blinked, etc). After doing this for about a dozen different actions, I stopped and saved the log file.

Now, all I had to do was go through the list and start picking out some common things. I saw that every event had one pair of command codes in common. Looking at my notes, the one thing that every event had in common was that it blinked a particular icon. I now figured out the first code was to turn the icon on, and the other to turn it off.

Comparing them, they were very similar codes. Almost all zeros, except for the last byte (which was identical), and one of the other bytes had a single bit set in one of the codes but not the other. I quickly figured out that the last byte indicated that we were toggling the icons, and which bits were set in the other bytes indicated which icons to turn on.

I then looked at my written list. One of the other action had toggled a different icon. I suspected that If I looked in the corresponding series of events, I'd find an event where the command code had the same last byte, but a different set of bits turned on in the other bytes. Indeed, there was. I had now figured out how to toggle the icons. All that was left was to determine which bits handle which icons...a trivial task.

Comming Attractions!

Before I got much further in the debugging, I decided I needed to test my theory about the icon command. It was time to start writing a very basic driver. In my next post, I'll cover writing the first bits of driver code and putting my theories about the protocol to the test. here to read more!

Wednesday, March 26, 2008

Got my Thermaltake DH-101 case with iMon LCD

I'm currently in the process of building a dedicated frontend box for my living room. Choosing most of the hardware was easy, since I'm modeling this after my other myth boxes. However, for the case, I wanted something that would blend into the entertainment center a bit better.

After looking for options for several weeks, trying to decide which HTPC case I like, I finally settled on the Thermaltake DH-101 case. It arrived yesterday, and I quickly began putting it together. Once it was up and running, my first task was to figure out how to get the new hardware features (the LCD and front panel control buttons) working. It's been tough, but I'm making progress.

iMon hardware is not linux friendly

Not that it was any surprise, but Soundgraph (makers of the iMon hardware) have been less than helpful with using the iMon hardware on linux. They refuse to release a linux driver for the hardware, and that's really not such a big deal. There are plenty of people willing to write the drivers for them (as is usually the case for hardware under linux). However, they also refuse to release the protocol for the hardware. Thats not such a big deal either. Again, plenty of hardware hackers out there enjoy reverse engineering this stuff.

The thing that is most annoying is that, after people went through the processes of reverse engineering the protocol and writing the driver for it, Soundgraph decided to suddenly change the hardware's protocol, thus breaking a lot of the work that had been done. Luckily (as can be expected) people have already gotten underway figuring things out again.

The forums over at have been filled with discussion about the iMon hardware, with lots of helpful advice on getting the hardware working. There's even info and patches that explain how to get the new iMon hardware (denoted by the hardware ID 15c2:0038). I wasn't having any luck at first, but I'm starting to make some progress here. I'll post more details in the coming days as I come up with a more concrete description of just what it takes.

Initial impressions on the case

The case is very nicely constructed, and looks even better in person that what I had thought from the photos. Assembly was nice and easy, organization of the case was very good. However, I do have a few complaint. First, the stock fans are quite loud. I'm going to have to replace them with something else if this is to go in the living room. Second I'm a bit disappointed with the LCD. Besides the fact that I ended up with the new "redesigned, for more difficult linux compatibility" model, I'm also disappoint by which LCD color they used.

The photos on the Thermaltake website all show the system used with the Soundgraph negative white LCD. However, the one I got is using the negative blue. Negative white has a dark, unlit background, so all you really see is the lit up elements (text and symbols). The negative blue, however, has the whole display backlight with a dimmer blue light. That has 2 downsides. First, it gives off more light. When you are in a datk room watching a movie, the fewer sources of bright light, the better. But more so than that, having the whole background lit up means less contrast for the characters being displayed. here to read more!

Tuesday, March 25, 2008

Enabling Quality of Service for the HDHomeRun

A few times recently, I've had problems where I was generating a large amount of bandwidth at the same time mythtv was recording a few HD programs from my HDHomeRun. The HDHomeRun transmits its data over the network via UDP instead of TCP, so when it ends up on the losing end of an oversaturated network, it's packets just get dropped and the data is never retransmitted. The end result is a lot of packet loss, and the recording will be full of skips and other corruption. Having damaged recordings is an unacceptable situation, and was something that I needed to resolve. Simply scheduling any heavy network activity around the recording schedule was not acceptable, either. I needed a better solution.

Upgrading the network

As it just so happens, I also had another problem at the same time. My home network had grown considerably, and I was now out of ports on my router and switch. I needed to add another switch to the network. In looking around, I found the D-Link DGS-2208 and it seemed to be both inexpensive and had very good reviews. It also had something else I found for 802.1p Quality of Service delivery.

QoS on the HDHomeRun

When I saw 802.1p support in the feature list, something clicked in my mind. I remember reading once that the HDHomeRun could enable Quality of Service flagging on its packets. I figured that would be a great feature to enable, to ensure that the HDHomeRun got priority over other devices when the network starts getting saturated.

I figured it would be as simple as changing a setting in the HDHomeRun, and all data would be streamed with a QoS flag. Do that once, and it would be transparent to everything else. I promptly opened up a support ticket with Silicon Dust to find out how to do it. I got a prompt response back indicating how it could be done.

As I expected, the solution was quite simple. Simply pass an extra flag to hdhomerun_config when you tell it where to stream the data to. Instead of

hdhomerun_config FFFFFFFF set /tuner0/target "udp://"

it would be

hdhomerun_config FFFFFFFF set /tuner0/target "udp:// qos"

(note...the quotes in the parameter list are important so that the qos string doesn't get treated as a separate parmaeter).

I gave it a try and it worked. That was a very easy solution. However, there was a slight problem here. The way this was enabled meant that a patch would need to be applied to mythtv to enable this to happen each time it opened up the stream.

Patching MythTV

The patch to make this happen wasn't very difficult. There were only a few tiny changes that needed to take place. A single line of code could be used to accomplish this, except for the fact that 802.1p tagging is applied as part of the 802.1q standard for virtual LANs. This meant in order to QoS tag the packet, the packet had to be destined for a VLAN (the HDHomeRun uses VLAN 0).

By default, linux will ignore packets that are received for a VLAN unless it has been explicitly configured to do otherwise. This means that a quick and dirty patch to mythtv would break HDHomeRun functionality for anyone who doesn't have VLANs configured, as the packets from the HDHomeRun would never be handled. Obviously, this needed to be a feature that could be toggled on/off in the capture card setup of mythtv-setup. This made the patch just a tiny bit more complex, because it requires a schema change to the database so you have somewhere to store this flag. Regardless, I was quickly able to code up the patch. I'll release it soon, but I first need to run a few things by the mythtv-dev mailing list.

Enabling VLAN support under Debian

As I mentioned, linux ignores packets destined for VLANs unless explicitly configured to do otherwise. It turns out that configuring Debian to handle a VLAN wasn't all that difficult.

The first step was to install the vlan package ( apt-get install vlan ). Once that was done, you needed load the 8021q module ( modprobe 8021q ). Finally, you just needed to tell linux to accept packets for VLAN 0 on your adapter ( vconfig add eth0 0 ). Your network is now accepting VLAN 0 packets. This created an entry for eth0.0 under /proc/net/vlan/. If you view its contents ( cat /proc/net/vlan/eth0.0 ), it will give you network usage statistics for that VLAN.

That last thing you need to do is make sure your VLAN configuration survives a reboot. Simply create a script called /etc/init.d/vlan that runs your modprobe and vconfig commands. This script can then be run automatically when your eth0 interface comes up by adding the line "up /etc/init.d/vlan" to your /etc/network/interfaces file in the section for "iface eth0". here to read more!

Thursday, March 20, 2008

Patch to configure mythmusic exit action

I released a tiny new patch today. This patch is for the mythmusic plugin. It allows you to configure the action you want mythtv to take when exiting the mythmusic plugin while music is playing back.

Currently, when you are use the mythmusic pluging and are playing some music, if you try to exit the plugin (perhaps to do other things in myth), you get prompted whether you want to stop playback or contiue playback. For myself, if I didn't want the music to keep playing, I'd hit the stop key first, so getting prompted every time gets a bit annoying. In addition, if I hit a jumppoint key (perhaps to jump into the photo gallery), music playback stops instantly with no option to exit.

This patch gives you the option to configure the action to take when exiting. By default, it maintains the current behavior. However, you can also set it to always stop playing or to always continue playing. In either case, you can exit myth without being prompted. In addition, if you set it to always continue playing, it will do so even if you exit the plugin by using a jumppoint.

This patch will work with either myth 0.21-fixes or trunk.

You can download the patch file from Ticket #5008. here to read more!

Wednesday, March 19, 2008

My USB-UIRT failed on me

Just when my wife was REALLY starting to take a liking to mythtv (she's been rejecting the mythbox for years, all the while desperately holding onto the TiVo), I suffered a tiny setback to my progress. I had to experience a hardware USB-UIRT died on me. Luckily my wife is pretty understanding of stuff like that, and I was able to get things back up and running quickly enough, so she really hardly noticed:

My previous IR experience

For several years, I had been using a IRA-3 serial port IR receiver from I was very pleased with the device, and it served me quite well. However, when I decided to rebuild my entire mythtv system late last year, I decided I had a few additional needs. One, I wanted something that could transmit as well as receive. Second, I wanted a USB device that I could use to wake the machine up from suspend-to-ram when I pressed the power button on the remote. After searching around, the USB-UIRT seemed to be the device that best suited my needs and had some happy users.

Unhappy with the USB-UIRT

My experiences with the device, however, had been less than satisfactory. First, there had been some code reverted in the latest kernels, and the device no longer functioned without patching and rebuilding a kernel driver. After spending a lot of time figuring that out, and then finally successfully getting it all working, the next release of the kernel seemed to fix the problem, so all of my work accomplished little. However, being that linux isn't an officially supported platform for the USB-UIRT, I could hardly blame the manufacturer (well...I guess I COULD blame them for not caring to support linux).

Once the device was up and running, my next task was to program the device. I immediately had trouble, as irrecord kept telling me there was an error reading the signal. After much trial and error, I was able to brute force my way through the errors and get it to record my lircd.conf file. By contrast, my IRA-3 worked perfectly every time in this regard.

Once that was working, the next thing I noticed was that the device was VERY finicky about the remote being pointed directly at it. If I pointed it just a tad too high, low, or to the side, it would only pick up the IR signal intermittently. A little more that that and it wouldn't see it at all. By contrast, with my IRA-3, I could point the remote at the ceiling, the opposite wall, or even stand in an adjacent room and it would still pick up the remote.

Next came the task of getting the device to wake the machine from suspend. I was able to program it with my remote's power button signal and get it to wake the machine successfully. However, I then ran into the discovery that, as soon lirc tried to use the USB-UIRT, the device's state would somehow get corrupted and it would no longer wake the machine up. I would have to physically unplug the device before it would wake the system again. Thus I had my choice of using it for lirc, or using it to wake the machine, but not both.

The final straw came this weekend. The USB-UIRT was working perfectly. I left the room, came back 30 minutes later, and the red light was stuck on. The device was no longer responding to IR signals, and nothing could get it to work again (rebooting or unplugging it didn't help). There were other posting of the same problem in the support forum, but no response was ever posted by the manufacturer. Now it looks like I'll need to send it back.

Final outcome

Overall, I was quite disappointed in the device. It's performance was inferior to the IRA-3 in almost every respect. The one aspect where the USB-UIRT actually didn't disappoint me was with the IR emitter. I was able to get the IR emitter working successfully with little effort. However, I never got a chance to actually implement that aspect of it on my system, so I never got to put it through its paces.

For now, luckily my IRA-3 was still sitting around, unused and functional. I was able reconfigure my myth frontend (drivers, config files, and scripts) and get it working in relatively short order. My wife barely noticed downtime.

The only downside to the IRA-3...I've only got one serial port, and now I'm using it. I was just about set to start controlling my TV via the RS-232 serial port, but now I have to put that plan on hold. I've ordered a PCI serial port card and am waiting for it to arrive before I can continue. I've also still got to find a solution for waking the machine from suspend, and I may need to come up with another device to do the IR transmit functionality. here to read more!

Blog spam is a PITA

I'm a few days later than expected in getting this blog started. It seems that google suspected my blog was blog spam (for reasons unknown) and locked it, so I had to wait for them to fix it. So, now it's time to get started...

Don't bother to click this link here to read more!

Sunday, March 16, 2008

First Post

I thought it would be useful to have a place where I can put some of my daily thought on using and developing mythtv. Somewhere to talk about features I'm working on, patches I release, problems I run into, things I discover, etc.

Don't bother to click this link here to read more!