此方案用于实现Android主板的定时开机与Watchdog功能，应用于一些特殊产品，如：广告机、自动售货机等。

框图

framework.png

MCU原理图

sch.png

说明

1. Watch Dog
   Watch Dog功能默认关闭，直到Android发送命令打开Watch Dog功能。如果Watch Dog功处于打开状态，Android系统会在小于Watch Dog超时时长内定时发送心跳数据给MCU，如果Watch Dog超时时长到，仍未收到心跳数据，则拉低RESET引脚10ms，使CPU复位重启。
2. 定时开机
   当MCU收到数据后启动计时，时间到拉低POWER引脚10ms，使CPU开机，同时清除本次定时任务，直到下次CPU重新下发新的定时任务。

协议

通信接口为I2C，从机地址：0x61

源码

Android-TimedBootDriver

API使用

IMcuService.aidl

package android.os;
 
/** {@hide} */
interface IMcuService
{
    int heartbeat();
    int setUptime(int time);
    int openWatchdog();
    int closeWatchdog();
    int setWatchdogDuration(int duration);
}

McuTest.java

package com.ayst.item;

import android.annotation.SuppressLint;
import android.content.Context;
import android.os.IBinder;
import android.os.IMcuService;
import android.os.RemoteException;

import java.lang.reflect.Method;

/**
 * Created by Administrator on 2018/11/6.
 */

public class McuTest {
    private IMcuService mMcuService;

    @SuppressLint("WrongConstant")
    public McuTest(Context context) {
        Method method = null;
        try {
            method = Class.forName("android.os.ServiceManager").getMethod("getService", String.class);
            IBinder binder = (IBinder) method.invoke(null, new Object[]{"mcu"});
            mMcuService = IMcuService.Stub.asInterface(binder);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /**
     * Heartbeat
     */
    public void heartbeat() {
        if (null != mMcuService) {
            try {
                mMcuService.heartbeat();
            } catch (RemoteException e) {
                e.printStackTrace();
            }
        }
    }

    /**
     * Set the boot countdown
     * @param time (unit: second)
     * @return <0：error
     */
    public int setUptime(int time) {
        if (null != mMcuService) {
            try {
                return mMcuService.setUptime(time);
            } catch (RemoteException e) {
                e.printStackTrace();
            }
        }
        return -1;
    }

    /**
     * Enable watchdog
     * @return <0：error
     */
    public int openWatchdog() {
        if (null != mMcuService) {
            try {
                return mMcuService.openWatchdog();
            } catch (RemoteException e) {
                e.printStackTrace();
            }
        }
        return -1;
    }

    /**
     * Disable watchdog
     * @return <0：error
     */
    public int closeWatchdog() {
        if (null != mMcuService) {
            try {
                return mMcuService.closeWatchdog();
            } catch (RemoteException e) {
                e.printStackTrace();
            }
        }
        return -1;
    }

    /**
     * Set watchdog over time duration
     * @param duration (unit: second)
     * @return <0：error
     */
    public int setWatchdogDuration(int duration) {
        if (null != mMcuService) {
            try {
                return mMcuService.setWatchdogDuration(duration);
            } catch (RemoteException e) {
                e.printStackTrace();
            }
        }
        return -1;
    }
}