i'm working on a Minix NEO X8-H (Android media center, 4.4.2) and i need to send HDMI-CEC command to TV: when my App receives a call i want to change automatically the TV Source to the Minix hdmi source.
Actually the Minix offer some options to enable HDMI-CEC and the media center software XBMC is reported to support CEC. But only in "receive mode" i guess: the user can command the Android device using TV remote. I want to work the opposite way. I browse XBMC's source code and i found very interesting code but do not know if it can be useful to me.
I found the serial device that get HDMI-CEC input commands
/dev/input/event7
The kernel references are placed at: "/sys/devices/virtual/input/input7/"
# cat /sys/devices/virtual/input/input7/name
cec_input
This is a part of dmesg log:
<5>[ 0.000000@0] Kernel command line: init=/init console=ttyS0,115200n8 no_console_suspend storage=5 cvbsdrv=0 vdaccfg=0xa007 logo=osd1,loaded,0x15100000,4k2ksmpte,full hdmimode=4k2ksmpte cvbsmode=576cvbs androidboot.firstboot=0 hdmitx=cec0
<4>[ 0.000000@0] kernel get hdmimode form uboot is 4k2ksmpte
<4>[ 0.000000@0] hdmitx: cec: Function List: disable, , ,
<4>[ 0.000000@0] hdmitx: cec: HDMI aml_read_reg32(P_AO_DEBUG_REG0):0x0
<4>[ 0.000000@0] hdmitx: cec: HDMI hdmi_cec_func_config:0x0
<4>[ 1.392440@1] hdmitx: cec: CEC not ready
<4>[ 4.872752@0] hdmitx: cec: CEC init
<4>[ 4.876194@1] hdmitx: cec: CEC task process
<4>[ 4.876398@0] hdmitx: cec: hdmitx_device->cec_init_ready:0x1
that proves the effective presence of HDMI-CEC built-in support.
I found libCEC and i managed to cross-compile it using Android NDK toolchain and i was able to install "libcec.so" and a demo client binary "cec-client" onto the Minix.
These are the build options:
asd@vm-ubuntu:~/Desktop/libcec/libcec-master/build$ cmake ..
-- Could NOT find PythonLibs (missing: PYTHON_LIBRARIES PYTHON_INCLUDE_DIRS)
-- Could NOT find PythonLibs (missing: PYTHON_LIBRARIES PYTHON_INCLUDE_DIRS)
-- Could NOT find PythonLibs (missing: PYTHON_LIBRARIES PYTHON_INCLUDE_DIRS)
-- Could NOT find PythonLibs (missing: PYTHON_LIBRARIES PYTHON_INCLUDE_DIRS)
-- Could NOT find SWIG (missing: SWIG_EXECUTABLE SWIG_DIR)
-- Configured features:
-- Pulse-Eight CEC Adapter: no
-- Pulse-Eight CEC Adapter detection: no
-- lockdev support: no
-- xrandr support: no
-- Raspberry Pi support: no
-- TDA995x support: no
-- Exynos support: no
-- Python support: no
-- lib info: compiled on Linux-3.13.0-35-generic, features: P8_USB
-- Configuring done
-- Generating done
-- Build files have been written to: /home/asd/Desktop/libcec/libcec-master/build
I know that libcec works with an external hdmi-cec controller or, if build with Raspberry support feature it can runs smoothly on a raspi, using its integrated video controller.
If it can run on raspi it must be able to run on a Minix, i guess.
The cec-client was a demo client, developed to communicate with a serial interface and actually it can not communicate with /dev/input/evet7 because of some errors:
root@NEO-X8:/data # cec-client -t p -p 4 /dev/input/event7
== using device type 'playback device'
using HDMI port '4'
CEC Parser created - libCEC version 3.0.0
opening a connection to the CEC adapter...
DEBUG: [ 7] Broadcast (F): osd name set to 'Broadcast'
ERROR: [ 3520] error opening serial port '/dev/input/event7': Invalid argument
ERROR: [ 3521] could not open a connection (try 1)
ERROR: [ 6355] error opening serial port '/dev/input/event7': Too many open files
ERROR: [ 6355] could not open a connection (try 2)
ERROR: [ 8243] error opening serial port '/dev/input/event7': Too many open files
ERROR: [ 8243] could not open a connection (try 3)
ERROR: [ 9501] error opening serial port '/dev/input/event7': Too many open files
ERROR: [ 9501] could not open a connection (try 4)
unable to open the device on port /dev/input/event7
NOTICE: [ 10506] connection opened
But AFAIK Hdmi-CEC use a serial communication protocol using pin 13 of the HDMI connector so even if "cec-client" is a demo client it must be able to work properly! As you see there is a problem on locking the device or something similar.
Problems:
If Java way is not possible there are no problems: my own app is built using Qt and actually i'm already using a couple of native shared librare ".so"
Anyone has tips? How can accomplish that?
My two cents on the issue:
I went through all the trouble you went, too, especially with libCEC, so I'd like to describe the only way I got any interaction going between an Android TV box and the TV connected to it with HDMI cable.
Send a request for connected device's power status
echo 0x40 0x8F > /sys/class/cec/cmd
To get the response, you can:
read the "registry"
cat /sys/class/cec/dump_reg
wait and look for the response in logcat
// Example:
02-06 16:33:10.568 4012 4105 D CEC : [cec_rx_loop]msg:04 90 00
02-06 16:33:10.570 4012 4105 D HdmiCecExtend: onCecMessageRx
02-06 16:33:10.657 4012 4012 W HDMI : [1]:Unhandled cec command:<Report Power Status> src: 0, dst: 4, params: 00
02-06 16:33:10.762 4012 4104 D CEC : [cec_send_message][4 -> 0]len:3, body:00 90 00 , result:success
Magic numbers (codes) explanation:
40 - Playback device #1
04 - TV device #1
On - 90 00
Off - 00 00 // in registry or no response at all in logcat
Other available codes can be constructed or read on Cec-O-Matic or amlogic.
I still have to try and get to Android's HdmiControlService but I still don't know how, probably through Java reflection. You can see HdmiCecExtend: onCecMessageRx so the API is available on the device, but you cannot use it in Android Studio, as far as I know, it's only available to Android TV vendors.
Will update if anything comes along.