On USB projectors, linux and libam7xxx

by ao2, January 18, 2012

I was looking into compact/mini/pico/handheld projectors, and I obviously wanted something I could use under GNU/linux, there were basically two choices:

Pick up a projector with VGA/HDMI: Operating System independent.
Pick up a USB projector: shipped only with drivers for MS Windows (and sometimes for MacOSX too).

Since the first choice was more expensive and I verified that writing a driver for the second case wasn't too hard, I picked up an Acer C110, I paid it about 160 €, but you can find it even cheaper somewhere else, grr.

AM7X or AM7XXX

The C110 is based on an Actions Micro AM7212P IC and uses USB bulk transfers with a simple packet based protocol on top to exchange data and commands to and from a host system and the AM7XXX chip.

Other projectors using the same protocol are:

These projectors use the USB Vendor and Product IDs 1de1:1101 in mass storage mode and 1de1:c101 in display mode.

Some DPFs too (from Hannspree for instance) are known to use these chips but I don't know yet if they can be put in USB display mode.

I will refer to these devices as either AM7X or AM7XXX devices.

Open Source driver for AM7XXX devices

Reto Schneider and I are reverse engineering the USB protocol used by these devices, using USB dumps and disassembling the Windows device driver, and a basic but already usable library to communicate with those AM7x based projectors can be found in libam7xxx. Reto was the first to start working on that, in the form of acerc11xdrv.

So you can now get these projectors to work wherever libusb-1.0 works, that means you can use them with your phone if it can run GNU/Linux for instance, or even Android/Linux but I don't have an Android device to verify that.

For now all the communication about the development is happening on the #am7xxx IRC Channel on the Freenode Network, come find us, and let us know if you want to help: like hosting a mailing list for us, or sponsoring some hardware (USB projectors you want to use freely or devices you want to use these projectors with).

Side note: the user manuals of these devices sometimes refer to the functionality of displaying images over USB as Display over USB (or DoUSB), this definition is used on a lot of projectors but I don't know if it refers always to the same protocol/mechanism to send images over USB.

Linux running ON other projectors

Incidentally, when I was doing my pre-purchase market research, I ran into several projectors which —unsurprisingly— are running a Linux system themselves (linux kernel, busybox, etc.), here is a summary of what I found out:

Samsung SP-H03 (not based on AM7X): the firmware image can be downloaded here, and Samsung is providing the source code for the Free Software used in it, you can find it on opensource.samsung.com (AFAIR Harald Welte gave them some directions about GPL compliance, right?).

This could be an interesting device if you want to run your own code on a projector.
Acer K330: based on a chip of the same am7x family as the C110.

The firmware image is available for download and it does contain the Linux kernel and other Open Source software, but the source code is not available, neither Linux or the GPL are mentioned in the downloadable documentation; I am going to do more research on this later to see if Acer is in compliance with the GPL.

Open Projectors?

Having the ability of processing an image before projecting it —either on an external system, or on the projector itself— opens up to a lot of possibilities, and I can foresee an increase of AR applications using projectors; so, do you think there is enough interest for an Open Projectors project? A place where we can share the techniques (keystone correction, or some more sophisticate anamorphic transformations by the means of a Camera-Projector system) and the Open Source software implementing them, all in a single place.

Get in touch if you have any ideas about that.

Short link: http://ao2.it/69

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Comments

by Dhanraj Rajput (not verified) | Thu, 16/02/2012 - 16:44

Hello , I Have C120. will

Hello ,

I Have C120. will this source work for C120 as well? if not then please let me know what changes i should be doing in the source.

thanks
Dhanraj Rajput

by ao2 | Thu, 16/02/2012 - 17:43

Hi Dhanraj, the library

Hi Dhanraj, the library should work with the C120 as well.

Contact me by email, or join the #am7xxx IRC channel on Freenode for more details.

Ciao, Antonio

by Dhanraj Rajput (not verified) | Mon, 20/02/2012 - 09:51

Acer C120 has Product ID

Acer C120 has Product ID 0xc102.

by Michael Renner (not verified) | Sun, 13/05/2012 - 14:57

How to compile? I try to

How to compile?

I try to compile the current version at my kubuntu 10.04 LST. I guess I have to use cmake for this, right?

renner@mars:/usr/src/libam7xxx-d526982$ cmake src
CMake Error at CMakeLists.txt:4 (find_package):
  Could not find module Findlibusb-1.0.cmake or a configuration file for
  package libusb-1.0.
  Adjust CMAKE_MODULE_PATH to find Findlibusb-1.0.cmake or set libusb-1.0_DIR
  to the directory containing a CMake configuration file for libusb-1.0.  The
  file will have one of the following names:
    libusb-1.0Config.cmake
    libusb-1.0-config.cmake
CMake Warning (dev) in CMakeLists.txt:
  No cmake_minimum_required command is present.  A line of code such as
    cmake_minimum_required(VERSION 2.8)
  should be added at the top of the file.  The version specified may be lower
  if you wish to support older CMake versions for this project.  For more
  information run "cmake --help-policy CMP0000".
This warning is for project developers.  Use -Wno-dev to suppress it.
-- Configuring incomplete, errors occurred!

The development libraries for usb userspace applications are installed

renner@mars:~$ cmake --version
cmake version 2.8.1
renner@mars:~$ dpkg --list | grep libusb
ii  libusb-0.1-4                                       2:0.1.12-14ubuntu0.2                                 userspace USB programming library
ii  libusb-1.0-0                                       2:1.0.6-1                                            userspace USB programming library
ii  libusb-1.0-0-dev                                   2:1.0.6-1                                            userspace USB programming library developmen
ii  libusb-dev                                         2:0.1.12-14ubuntu0.2                                 userspace USB programming library developmen
ii  libusbmuxd1                                        1.0.2-1ubuntu2                                       USB multiplexor daemon for iPhone and iPod T

Any hint?

Thanks

by ao2 | Sun, 13/05/2012 - 20:30

Hi Michael, this is how you

Hi Michael,

this is how you compile the code:

renner@mars:/usr/src/libam7xxx-d526982$ mkdir build
renner@mars:/usr/src/libam7xxx-d526982$ cd build
renner@mars:/usr/src/libam7xxx-d526982/build$ cmake ../
renner@mars:/usr/src/libam7xxx-d526982/build$ make

Ciao,
Antonio

by Giuseppe (not verified) | Thu, 17/05/2012 - 10:12

Hello it's possible to use

Hello it's possible to use libam7xxx library on Windows platform? I am currently testing this library with a C120 acer projector but libusb give me following errors

libusb: 0.116006 error [composite_submit_control_transfer] no libusb supported interfaces to complete request
libusb: 0.121007 error [composite_submit_bulk_transfer] unable to match endpoint to an open interface - cancelling transfer

can you help me please

by ao2 | Thu, 17/05/2012 - 10:30

Hi Giuseppe, libam7xxx and

Hi Giuseppe,

libam7xxx and picoproj work on Windows, yes, info are in the README and HACKING documents.

But the problem in your case is that C120 is not supported (and cannot be) by libam7xx because it uses a different protocol to communicate with the host system.

If you want I can put you in contact with other owners of C120 if you guys want to reverse engineer the protocol yourselves. Join the #am7xxx IRC channel or write me privately.

Alternatively, if you really need an open source driver for C120, you could donate a C120 to me and I'll try to do that :)

Ciao, Antonio

by Giuseppe (not verified) | Thu, 17/05/2012 - 14:33

Hi Antonio, many thanks for

Hi Antonio,
many thanks for your prompt reply! Unfortunately I have supposed that C120 product was compatible with libam7xxx library.
For now I think I will just use regular projector drivers, because I am not able to do reverse enginering of protocol. Anyway many compliments for your great job!
Ciao, Giuseppe

by Michael Renner (not verified) | Sun, 17/06/2012 - 18:31

There is one more

There is one more error:

root@solaris:/usr/src/libam7xxx-d526982/build# cmake ../
-- The C compiler identification is GNU
-- Check for working C compiler: /usr/bin/gcc
-- Check for working C compiler: /usr/bin/gcc -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Found Git: /usr/bin/git 
-- Found date: /bin/date
-- Generator is: Unix Makefiles
--  - "git archive" will use the date too!
-- Found libusb-1.0:
--  - Includes: /usr/include/libusb-1.0
--  - Libraries: /usr/lib/i386-linux-gnu/libusb-1.0.so
-- Looking for avformat_open_input
-- Looking for avformat_open_input - not found.
CMake Error at examples/CMakeLists.txt:27 (message):
  Function avformat_open_input missing.  Please use a newer FFmpeg release.


-- Configuring incomplete, errors occurred!

It is the current kubuntu version 12.04. It comes with
ffmpeg 0.8.1. I can compile the current ffmpeg version 0.11.1, but will this solve the problem?

Thanks

by ao2 | Wed, 20/06/2012 - 17:32

Michael, I'll try to figure

Michael, I'll try to figure out what the minimum required version is and that highlight that in the documentation.

I really want to avoid adding compatibility code for older ffmpeg/libav versions.

Thanks, Antonio

by Michael Renner (not verified) | Mon, 25/06/2012 - 22:58

Moin, no problem, I installed

Moin,

no problem, I installed the current ffmpeg-version to /usr/local. But now I run into an other problem: Linking the play binary fails:

[ 66%] Built target am7xxx-static                                                                                         
Linking C executable ../bin/am7xxx-play
/usr/local/lib/libavformat.a(swfdec.o): In function `swf_read_header':                                                    
/usr/src/ffmpeg/libavformat/swfdec.c:107: undefined reference to `inflateInit_'
/usr/local/lib/libavformat.a(swfdec.o): In function `zlib_refill':
/usr/src/ffmpeg/libavformat/swfdec.c:75: undefined reference to `inflate'
/usr/local/lib/libavformat.a(swfdec.o): In function `swf_read_close':
/usr/src/ffmpeg/libavformat/swfdec.c:269: undefined reference to `inflateEnd'
/usr/local/lib/libavdevice.a(lavfi.o): In function `lavfi_read_packet':
/usr/src/ffmpeg/libavdevice/lavfi.c:295: undefined reference to `av_buffersink_get_buffer_ref'
.
.
.

The debian packages liblz-dev and liblz1-dev are installed. Anyhow: I can not find the "-lz" switch in the makefile. Any hint?

by ao2 | Tue, 26/06/2012 - 10:15

Hi Michael, about passing

Hi Michael,

about passing options to the compiler you can do something like:

$ CFLAGS="-lz" cmake ../

Or alternatively you can disable things when compiling ffmpeg/libav.

And be sure that cmake picks up ffmpeg headers from /usr/local/include, as a general rule you should compile using the headers of the same version of the library you are going to link the binary to.

Another choice you can explore is to find an Ubuntu PPA which provides a newer ffmpeg/libav version already packaged.

by Michael Renner (not verified) | Tue, 26/06/2012 - 22:13

Moin, thanks for your work

Moin,

thanks for your work and all the help you gave me here. I maneged it to compile the source. It's running fine now! Now I'm going to compile the application on my other machines. Maybe writing some scripts to start it automaticly by plugging the USB connector in or so ;-)

by roliopolio (not verified) | Sun, 05/08/2012 - 14:49

Hi, I have just managed to

Hi,
I have just managed to build picoproj under Xubuntu 12.04.

If it helps anyone I've written a rough log of my attempt at

http://roliopolio.weebly.com/acerc110.html

I haven't managed to build am7xxx-play yet because I'll probably need to write an xcb.pc.

So, thanks to ao2 and other shoulders for this library; I now have a nice 50 lumen projector for €50 off Ebay.

Next, I'll need a way to make it display my laptop screen, possibly in reverse as a back projector.

by ao2 | Mon, 06/08/2012 - 11:34

@rp, try installing

@rp, try installing libx11-xcb-dev, note that XCB is optional anyways.

BTW, join the IRC channel if you need more help with compiling the example programs.

by konstl (not verified) | Fri, 14/09/2012 - 19:54

Hi, is there any possibility

Hi,

is there any possibility to pass a device id to am7xxx-play?
I own two C112 projectors from Acer and want to display
different images on each of them

Konstantin

by ao2 | Fri, 14/09/2012 - 21:38

Hi Konstantin, the library

Hi Konstantin,

the library has support for multiple devices, but the functionality is not exposed in the example programs because it has not been tested (none of us has more than one projector).

Join the IRC channel and I'll give you an experimental patch to test. Please try to hang out for a while in the channel, we may be slow to answer :)

by ralf (not verified) | Sun, 16/09/2012 - 19:37

hi guys ein kleines howto

hi guys

ein kleines howto findet ihr auf ubuntuusers.de

http://wiki.ubuntuusers.de/Baustelleamer_Acer_C110

viel erfolg und spass beim schaun.

lg ralf

by paul (not verified) | Sun, 04/11/2012 - 23:15

Hi, on my mk802 armhf i am

Hi, on my mk802 armhf i am trying to build like this:

root@debian:/test/2# git clone http://git.ao2.it/libam7xxx.git
Cloning into 'libam7xxx'...
root@debian:/test/2# cd libam7xxx
root@debian:/test/2/libam7xxx# mkdir build
root@debian:/test/2/libam7xxx# cd build
root@debian:/test/2/libam7xxx/build# cmake -D CMAKE_BUILD_TYPE=debug -D STRICT_COMPILATION_CHECKS=ON ../
-- The C compiler identification is GNU 4.6.3
-- Check for working C compiler: /usr/bin/gcc
-- Check for working C compiler: /usr/bin/gcc -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Found Git: /usr/bin/git (found version "1.7.10.4")
-- Found date: /bin/date
-- Generator is: Unix Makefiles
--  - "git archive" will use the date too!
-- Found libusb-1.0:
--  - Includes: /usr/include/libusb-1.0
--  - Libraries: /usr/lib/arm-linux-gnueabihf/libusb-1.0.so
-- Looking for avformat_open_input
-- Looking for avformat_open_input - found
-- Looking for sigaction
-- Looking for sigaction - found
-- Looking for strtok_r
-- Looking for strtok_r - found
-- Found PkgConfig: /usr/bin/pkg-config (found version "0.26")
-- checking for module 'xcb'
--   found xcb, version 1.8.1
-- Found XCB: /usr/include
-- Found libusb-1.0:
--  - Includes: /usr/include/libusb-1.0
--  - Libraries: /usr/lib/arm-linux-gnueabihf/libusb-1.0.so
-- Found Doxygen: /usr/bin/doxygen (found version "1.8.1.2")
-- Configuring done
-- Generating done
-- Build files have been written to: /test/2/libam7xxx/build
root@debian:/test/2/libam7xxx/build# make
Scanning dependencies of target am7xxx
[ 14%] Building C object src/CMakeFiles/am7xxx.dir/am7xxx.c.o
[ 28%] Building C object src/CMakeFiles/am7xxx.dir/serialize.c.o
Linking C shared library ../lib/libam7xxx.so
[ 28%] Built target am7xxx
Scanning dependencies of target am7xxx-static
[ 42%] Building C object src/CMakeFiles/am7xxx-static.dir/am7xxx.c.o
[ 57%] Building C object src/CMakeFiles/am7xxx-static.dir/serialize.c.o
Linking C static library ../lib/libam7xxx.a
[ 57%] Built target am7xxx-static
Scanning dependencies of target am7xxx-play
[ 71%] Building C object examples/CMakeFiles/am7xxx-play.dir/am7xxx-play.c.o
Linking C executable ../bin/am7xxx-play
[ 71%] Built target am7xxx-playa
Scanning dependencies of target am7xxx_mode_switch
[ 85%] Building C object examples/CMakeFiles/am7xxx_mode_switch.dir/am7xxx_mode_switch.c.o
Linking C executable ../bin/am7xxx_mode_switch
[ 85%] Built target am7xxx_mode_switch
Scanning dependencies of target picoproj
[100%] Building C object examples/CMakeFiles/picoproj.dir/picoproj.c.o
Linking C executable ../bin/picoproj
[100%] Built target picoproj

witch to me looks ok, but when i try to access the files, it acts as if nothing is there.

root@debian:/test/2/libam7xxx/build# cd bin
root@debian:/test/2/libam7xxx/build/bin# cd picoproj
-bash: cd: picoproj: Not a directory
root@debian:/test/2/libam7xxx/build/bin# ls
am7xxx_mode_switch  am7xxx-play  picoproj
root@debian:/test/2/libam7xxx/build/bin# picoproj
-bash: picoproj: command not found

i am a complete noob to linux so i am probably missing the obvious.
Could someone tell me what i do wrong ?(ps, i am installing it on a wheezy headless debian version through ssh)

by ao2 | Mon, 05/11/2012 - 00:15

Hi Paul, in order to execute

Hi Paul,

in order to execute programs in the current working directory you have to use the ./ prefix, so the command will be ./picoproj -h.

The prefix is not necessary for programs in one of the directories listed in the PATH environmental variable. You can look up on the web for more details on that.

Of course feel free to keep asking libam7xxx specific questions.

Ciao, Antonio

by paul (not verified) | Mon, 05/11/2012 - 08:31

Tnx a lot, that did the trick

Tnx a lot, that did the trick :)

by paul (not verified) | Mon, 05/11/2012 - 08:58

a quick followup

a quick followup question.
The device that i would like to use my picobeamer with, does not use a normal videocard.
I installed xfce, but it gives me an error about not having found a screen.
I would like it to use the picobeamer as primary (and only) screen.
Happen to know of a guide that can help me achieve this, or got any tips?

by ao2 | Mon, 05/11/2012 - 14:35

If the device has a

If the device has a framebuffer interface (/dev/fb0) then you can easily use am7xxx-play with a command line like ./am7xxx-play -f fbdev -i /dev/fb0.

If you want to run Xfce, Xorg could use this interface too with its own fbdev driver IIRC; once you got Xorg running you can use am7xxx-play with the x11grab format instead, look at the help or at the man page.

If not even a framebuffer interface is available then you could try with the Virtual Frame Buffer (vfb) kernel driver or with the xf86-video-dummy driver for Xorg.

by Jonas (not verified) | Sat, 19/01/2013 - 15:56

Any news regarding

Any news regarding C120?

Sincerely,

by ao2 | Sat, 19/01/2013 - 17:10

Hi Jonas, The Acer C120

Hi Jonas,

The Acer C120 supports a different protocol to send images to the projector via USB, it won't be supported by libam7xxx.

If I had one of those I could write a linux driver for it, but I do not plan on getting one by myself.

Regards, Antonio

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