Android System Power Indicator Cubietruck

Please move first, the operation of the LED, we use the same battrey_leds.sh
http://forum.cubietech.com/forum.php?mod=viewthread&tid=3212&highlight=%E5%B5%8C%E5%85%A5%E5%BC%8F%E5% Ad%a6%e4%b9%a0
[Embedded learning]led subsystem and LED trigger

Refer to the following three blog posts

1. How system services are started

http://blog.csdn.net/windskier/article/details/6417657

2. Android Batteryservice

Http://www.cnblogs.com/armlinux/archive/2010/09/15/2396916.html

3. Android 2.3 Battery Management

http://blog.csdn.net/z642010820/article/details/7341469


Android below also calls the same battrey_leds.sh file
but Android's Uevent trigger event is already in the system's own battery service, and we just need to execute the script battrey_leds.sh in it.
as you can see, only after the JNI updates the current value, the SH is executed

===== to do a brief explanation ========

1. Android System Services

V2.0_a20\android\frameworks\base\services\java\com\android\server\systemserver.java

battery = new Batteryservice (context, lights);//Battery Service

2. Android Battery Service

V2.0_a20\android\frameworks\base\services\java\com\android\server\batteryservice.java

mpowersupplyobserver.startobserving ("subsystem=power_supply");//register uevent, monitor power_supply

Uevent and kernel socket communication, a dead loop, the kernel has an event escalation, trigger onuevent

Public

void Onuevent (Ueventobserver.uevent event) {
Synchronized (MLock) {
Updatelocked (); See 309L
}
}


Native_update (); Refresh power, invoke the function of the battery service JNI layer
Processvalueslocked ();//Publish a Power update broadcast

3. Android Battery Service JNI

V2.0_a20\android\frameworks\base\services\jni\com_android_server_batteryservice.cpp

This JNI shares variables with the Java layer

The power and other parameters are defined in the Java layer, defined in Batteryservice.java, and used here

android_server_batteryservice_update//Refresh power and other parameters

4. Android Uevent

V2.0_a20\android\\frameworks\base\core\java\android\os\ueventobserver.java

while (true)//A dead loop of the line thread, waiting for the kernel to escalate the event
Observer.onuevent (event);//CALLBACK The observer registers the Onuevent function, and finally calls the onuevent in Batteryservice.java

= = = Specific implementation steps = = =
1. In the JNI layer of the battery serviceadd script execution functions in Com_android_server_batteryservice.cpp

static int execmd (const char* cmd)
{ 

    if (!cmd)
   & nbsp    return-1;
                          
    INT ret = System (CMD);  
        if (Ret < 0) {
           &NB sp;    Aloge ("==========execmd error '%s '", cmd);         
  &NBSP;&NBS P    }
        
    return 0;
}

exposed tointerface of the Batteryservice.javanative_setbatleds

//Set battery light

static void Android_server_batteryservice_setbatleds () { 
    ALO GE ("==========android_server_batteryservice_setbatleds");  

        execmd ("sh/system/bin/battrey_leds.sh");  
}

//Add set battery light native_setbatleds
static Jninativemethod smethods[] = {
     /* name, Signa ture, Funcptr */
        {"Native_update", "() V", (void*) android_server_ Batteryservice_update},
    {"Native_shutdown", "() V", (void*) Android_server_batteryservice_ shutdownnotfrompms},        
    {"Native_setbatleds", "() V", (void*) android_server_batteryservice_setbatleds},           
};

2. In the battery serviceBatteryservice.javaThe JNI interface is declared in the

private native void Native_setbatleds ();

Called in updatelocked ().

private void updatelocked () {
if (!mupdatesstopped) {
Update the values of Maconline, et. All.
Native_update ();

JNI Layer Set Battery light
Native_setbatleds ();

Process the new values.
Processvalueslocked ();
}
}        

3. However, you need to be aware of file node permissions
in Android/device/softwinner/sugar-cubietruck/init.sun7i.rc

chown System System/sys/class/leds/xxx/brightness
Chown System System/sys/class/leds/xxx/trigger
CHOMD 0777/sys/class/leds/xxx/brightness
CHOMD 0777/sys/class/leds/xxx/trigger

XXX Replace the LED lights you want to operate

5. Put the battrey_leds.sh in
Android/out/target/product/sugar-cubietruck/system/bin
chmod +x

There is another way to copy the battrey_leds.sh file into the file system.
can refer to
android\device\softwinner\sugar-cubietruck\sugar_cubietruck.mk
android/device/softwinner/wing-common/productcommon.mk
the Product_copy_files field in the

=====================================================
finally on my Android compilation steps summary

---------------Install JDK--------------
$ wget dl.cubieboard.org/software/tools/android/jdk1.6.0_45.tar.gz
$ sudo vim ~/.BASHRC

ADD:
Java_home=/work/tools/jdk1.6.0_45
Export JRE_HOME=/WORK/TOOLS/JDK1.6.0_45/JRE
Export path= $JAVA _home/bin: $JRE _home/bin: $PATH

$ source ~/.BASHRC


---------------Install Tools--------------
$ sudo apt-get install git gnupg flex bison gperf build-essential \
Zip curl Libc6-dev libncurses5-dev:i386 x11proto-core-dev \
libx11-dev:i386 libreadline6-dev:i386 mingw32 tofrodos \
Python-markdown libxml2-utils xsltproc zlib1g-dev:i386 libgl1-mesa-glx:i386 Libgl1-mesa-dev

$ sudo apt-get install Xsltproc
$ sudo apt-get Install Bison
$ sudo apt-get install Flex
$ sudo apt-get install Gperf
$ sudo apt-get install g++
$ sudo apt-get install Gcc-multilib
$ sudo apt-get install Libxml2-utils


---------------Download Source code--------------
$ mkdir/home/box/work/android_build
$ wget Http://dl.cubieboard.org/softwar ... droid_source.tar.gz
$ TAR-ZXVF v2.0_a20_android_source.tar.gz


---------------Build Kernel--------------
$ CD lichee/linux-3.4
$ make clean
$ cp arch/arm/configs/cubietruck_config. config
$ CD.
$./build.sh-p sun7i_android





---------------Build Android--------------
$ CD. /android
$ source Build/envsetup.sh
$ lunch
$//note:select Sugar_cubietruck-eng//For a targeted look, the suffix eng indicates that the engineering machine Userdebug the development of the debugger user end user machine
$ extract-bsp//Its role is to copy the drivers generated in the kernel into the product copy kernel-generated module and *.image
$ make-j8//First time here is best not add J8, otherwise memory is not enough error, if wrong, try to use J2, J4 try
$ pack

Android System Power Indicator Cubietruck