创Android Applicationproject：采用Eclipse的Android插入ADT创Androidproject，project名字Gpio，创建完成后，project文件夹packages/apps/文件夹下，并删除project文件夹下的gen文件夹。不删除的话会造成类反复的错误。

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project文件夹下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 := \ 后增加Gpio \

编译project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，開始更新目标板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 已经加入：(Android 从硬件到应用：一步一步向上爬 3 -- 硬件抽象层訪问硬件驱动 提到)

/dev/AdrIO                0666   root       root

启动，安装Gpio.apk。打开GPIO：

现象：

点击"Set"button：     D1灯亮    

点击"Clear"button：   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级别。经N渎MOS设备控制LED D1灯灭。