创建Android Application工程：使用Eclipse的Android插件ADT创建Android工程，工程名称为Gpio，创建完成后将工程目录拷贝到packages/apps/文件夹下，并删除工程目录下的gen文件夹，不删除的话会造成类重复的错误。
src/com/android/gpio/Gpio.java：
package com.android.gpio;
import com.android.gpio.R;
import android.app.Activity;
import android.os.ServiceManager;
import android.os.Bundle;
import android.os.IGpioService;
import android.os.RemoteException;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
public class Gpio extends Activity implements OnClickListener {
private final static String LOG_TAG = "com.android.Gpio";
private IGpioService gpioService = null;
private Button setButton = null;
private Button clearButton = null;
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
gpioService = IGpioService.Stub.asInterface(
ServiceManager.getService("gpio"));
setButton = (Button)findViewById(R.id.button_set);
clearButton = (Button)findViewById(R.id.button_clear);
setButton.setOnClickListener(this);
clearButton.setOnClickListener(this);
}
@Override
public void onClick(View v) {
if(v.equals(setButton)) {
try{
int val='1';
gpioService.setVal(val);
} catch (RemoteException e){
Log.e(LOG_TAG,"setting value");
}
}
else if(v.equals(clearButton)) {
try{
int val='0';
gpioService.setVal(val);
} catch (RemoteException e){
Log.e(LOG_TAG,"setting value");
}
}
}
} 布局res/layout/main.xml：
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent">
<Button
android:id="@+id/button_clear"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="@string/clear"
android:textStyle="bold"
android:layout_marginTop="140dp"/>
<Button
android:id="@+id/button_set"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="@string/set"
android:textStyle="bold"
android:layout_marginTop="0dp"/>
</LinearLayout> 字符串res/values/strings.xml：
<?xml version="1.0" encoding="utf-8"?> <resources> <string name="app_name">GPIO</string> <string name="set">Set</string> <string name="clear">Clear</string> </resources>AndroidManifest.xml：
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.android.gpio"
android:versionCode="1"
android:versionName="1.0">
<application android:icon="@drawable/ic_launcher" android:label="@string/app_name">
<activity android:name=".Gpio"
android:label="@string/app_name">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest> 编辑工程目录下Android.mk：
LOCAL_PATH:= $(call my-dir) include $(CLEAR_VARS) LOCAL_MODULE_TAGS := optional LOCAL_SRC_FILES := $(call all-subdir-java-files) LOCAL_PACKAGE_NAME := Gpio LOCAL_CERTIFICATE := platform include $(BUILD_PACKAGE) include $(call all-makefiles-under,$(LOCAL_PATH))编辑build/target/product/generic_no_telephony.mk：
在PRODUCT_PACKAGES := \ 后加入Gpio \
编译工程会生成Gpio.apk
make TARGET_PRODUCT=am335xevm_sk -j8 OMAPES=4.x到这一步一切准备工作都已就绪，开始更新目标板am335evm的文件系统：(左为host，右为evm)
out/target/product/am335xevm_sk/system/app/Gpio.apk ==> rootfs/ out/target/product/am335xevm_sk/system/framework/services.jar ==> rootfs/system/framework/ out/target/product/am335xevm_sk/system/framework/framework.jar ==> rootfs/system/framework/ out/target/product/am335xevm_sk/obj/lib/libandroid_servers.so ==> rootfs/system/lib/ out/target/product/am335xevm_sk/obj/lib/gpio.default.so ==> rootfs/system/lib/hw/
确保rootfs下 ueventd.rc 已经添加：(Android 从硬件到应用：一步一步向上爬 3 -- 硬件抽象层访问硬件驱动 提到)
/dev/AdrIO 0666 root root启动，安装Gpio.apk，打开GPIO：
现象：
点击"Set"按钮： D1灯亮 点击"Clear"按钮： D1灯灭
可见编写的APP通过调用硬件服务已经成功操作了AM335寄存器，改变AM335X_GPIO_LED4的电平，通过N沟MOS器件控制LED D1的亮灭。
Android 从硬件到应用：一步一步向上爬 6 -- 编写APP测试框架层硬件服务(完)
原文地址：http://blog.csdn.net/wu20093346/article/details/42085543
