CubieBoard2串口

CubieBoard2串口CubieBoard2串口

大家好,又见面了,我是你们的朋友全栈君。

关于Linux串口的一些小知识

  1. 串口名称使用 ls -l /dev/ttyS* 一般情况下串口的名称全部在dev下面,如果你没有外插串口卡的话默认是dev下的ttyS*,一般ttyS0对应com1,ttyS1对应com2,当然也不一定是必然的;
  2. 记得看一下串口的权限,是不是rw-rw-rw-,不是的话请运行chmod 666 /dev/ttyS\*给予可读写权限。

  3. 检查串口是否可用,可以对串口发送数据比如对com1口,echo Hello > /dev/ttyS0

  4. 串口驱动:cat /proc/tty/drivers/sw_serial

  5. 在PC上查看连接到CubieBoard2的串口设备:dmesg | grep ttyS*

    dmesg | grep ttyS*
    [ 0.000000] console [tty0] enabled
    [ 6.246827] systemd[1]: Created slice system-getty.slice.
    [ 13.740764] usb 3-4: ch341-uart converter now attached to ttyUSB0

以下内容均在Android Studio中实现

配置环境

配置JAVA

下载并配置好JAVA(JAVA_HOME、CLASSPATH、PATH),CMD中要能使用javah命令。

配置gradle

  1. gradle目录中找到gradle-wrapper.properties文件。
    修改其中配置为distributionUrl=https://services.gradle.org/distributions/gradle-2.10-all.zip
    gradle必须高于一定的版本,好像网上说NDK支持是后面加进来的。

    在菜单中File->Project Structure->Project中修改Gradle version为2.10也可以,改完后OK。

  2. 项目中的build.gradle

    // Top-level build file where you can add configuration options common to all sub-projects/modules. buildscript { 
         
        repositories {
            jcenter()
        }
        dependencies {
            classpath 'com.android.tools.build:gradle:2.1.2'
    
            // NOTE: Do not place your application dependencies here; they belong
            // in the individual module build.gradle files
        }
    }
    
    allprojects {
        repositories {
            jcenter()
        }
    }
    
    task clean(type: Delete) {
        delete rootProject.buildDir
    }
  3. NDK
    在项目中local.properties中配置ndk,ndk应该没什么要求。

    ndk.dir=D:\\Programs\\Androidsdk\\ndk-bundle
    sdk.dir=D:\\Programs\\Androidsdk

    我用的是AS自动下载配置的,版本为android-ndk-r12d。

工程

新建

  1. 新建一个类,类名为SerialPort。代码如下:

    package com.bilibili.www.serialporttest;
    
    import java.io.File;
    import java.io.FileDescriptor;
    import java.io.FileInputStream;
    import java.io.FileOutputStream;
    import java.io.IOException;
    import java.io.InputStream;
    import java.io.OutputStream;
    
    import android.util.Log;
    
    public class SerialPort { 
         
        private static final String TAG = "SerialPort";
    
        // JNI
        static {
            //指定库名,需要和build.gradle中一致
            try {
                System.loadLibrary("serial_port");
            }
            catch (UnsatisfiedLinkError e) {
                Log.d(TAG, "Unsatisfied Link error: " + e.toString());
            }
        }
    
        private static native FileDescriptor open(String path, int baudrate, int flags);
        public native void close();
    
        /* * Do not remove or rename the field mFd: it is used by native method close(); */
        private FileDescriptor mFd;
        private FileInputStream mFileInputStream;
        private FileOutputStream mFileOutputStream;
    
        public SerialPort(File device, int baudrate, int flags) throws SecurityException, IOException {
    
            /* Check access permission */
            if (!device.canRead() || !device.canWrite()) {
                try {
                    /* Missing read/write permission, trying to chmod the file */
                    Process su;
                    su = Runtime.getRuntime().exec("/system/bin/su");//获得root
                    String cmd = "chmod 666 " + device.getAbsolutePath() + "\n"
                            + "exit\n";//全部用户权限为可读写
                    su.getOutputStream().write(cmd.getBytes());
                    if ((su.waitFor() != 0) || !device.canRead()
                            || !device.canWrite()) {
                        throw new SecurityException();
                    }
                } catch (Exception e) {
                    e.printStackTrace();
                    throw new SecurityException();
                }
            }
            Log.d(TAG, "Start!!!!!!!");
            mFd = open(device.getAbsolutePath(), baudrate, flags);
            if (mFd == null) {
                Log.e(TAG, "native open returns null");
                throw new IOException();
            }else {
                mFileInputStream = new FileInputStream(mFd);
                mFileOutputStream = new FileOutputStream(mFd);
            }
        }
    
        // Getters and setters
        public InputStream getInputStream() {
            return mFileInputStream;
        }
    
        public OutputStream getOutputStream() {
            return mFileOutputStream;
        }
    }
    1. 打开terminal,输入cd <你的工程位置>\app\src\main\java;输入javah -jni <你的包名>.<类名>。这里是如javah -jni com.bilibili.www.serialporttest.SerialPort
      这样的命令,完成之后如果没有问题,会在java目录下出现一个com_bilibili_www_serialporttest_SerialPort.h的文件。

    2. <你的工程位置>\app\src\main目录下新建一个jni目录。

修改

  1. com_bilibili_www_serialporttest_SerialPort.h文件放进jni目录。

  2. jni目录下建立一个c文件,内容如下:

    /* * Copyright 2009-2011 Cedric Priscal * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */
    
    
    #include "com_bilibili_www_serialporttest_SerialPort.h"
    
    
    
    #include <termios.h>
    
    
    #include <unistd.h>
    
    
    #include <sys/types.h>
    
    
    #include <sys/stat.h>
    
    
    #include <fcntl.h>
    
    
    #include <string.h>
    
    
    #include <jni.h>
    
    
    //#include "android/log.h"
    
    #include <android/log.h>
    
    
    
    #ifdef __cplusplus
    
    extern "C" {
    
    #endif
    
    
    static const char *TAG="serial_port";
    
    /* 这三个函数是为了打印信息而存在 */
    
    #define LOGI(fmt, args...) __android_log_print(ANDROID_LOG_INFO, TAG, fmt, ##args)
    
    
    #define LOGD(fmt, args...) __android_log_print(ANDROID_LOG_DEBUG, TAG, fmt, ##args)
    
    
    #define LOGE(fmt, args...) __android_log_print(ANDROID_LOG_ERROR, TAG, fmt, ##args)
    
    
    static speed_t getBaudrate(jint baudrate)
    {
        switch(baudrate) {
        case 0: return B0;
        case 50: return B50;
        case 75: return B75;
        case 110: return B110;
        case 134: return B134;
        case 150: return B150;
        case 200: return B200;
        case 300: return B300;
        case 600: return B600;
        case 1200: return B1200;
        case 1800: return B1800;
        case 2400: return B2400;
        case 4800: return B4800;
        case 9600: return B9600;
        case 19200: return B19200;
        case 38400: return B38400;
        case 57600: return B57600;
        case 115200: return B115200;
        case 230400: return B230400;
        case 460800: return B460800;
        case 500000: return B500000;
        case 576000: return B576000;
        case 921600: return B921600;
        case 1000000: return B1000000;
        case 1152000: return B1152000;
        case 1500000: return B1500000;
        case 2000000: return B2000000;
        case 2500000: return B2500000;
        case 3000000: return B3000000;
        case 3500000: return B3500000;
        case 4000000: return B4000000;
        default: return -1;
        }
    }
    
    /* * Class: com_bilibili_www_serialporttest_SerialPort * Method: open * Signature: (Ljava/lang/String;II)Ljava/io/FileDescriptor; */
    JNIEXPORT jobject JNICALL Java_com_bilibili_www_serialporttest_SerialPort_open
            (JNIEnv *env, jclass thiz, jstring path, jint baudrate, jint flags)
    {
        int fd;
        speed_t speed;
        jobject mFileDescriptor;
    
        /* Check arguments */
        {
            speed = getBaudrate(baudrate);
            if (speed == -1) {
                /* TODO: throw an exception */
                LOGE("Invalid baudrate");
                return NULL;
            }
        }
    
        /* Opening device */
        {
            jboolean iscopy;
            const char *path_utf = (*env)->GetStringUTFChars(env, path, &iscopy);
            LOGD("Opening serial port %s with flags 0x%x", path_utf, O_RDWR | flags);
            fd = open(path_utf, O_RDWR | flags);
            LOGD("open() fd = %d", fd);
            (*env)->ReleaseStringUTFChars(env, path, path_utf);
            if (fd == -1)
            {
                /* Throw an exception */
                LOGE("Cannot open port");
                /* TODO: throw an exception */
                return NULL;
            }
        }
    
        /* Configure device */
        {
            struct termios cfg;
            LOGD("Configuring serial port");
            if (tcgetattr(fd, &cfg))
            {
                LOGE("tcgetattr() failed");
                close(fd);
                /* TODO: throw an exception */
                return NULL;
            }
    
            cfmakeraw(&cfg);
            cfsetispeed(&cfg, speed);
            cfsetospeed(&cfg, speed);
    
            if (tcsetattr(fd, TCSANOW, &cfg))
            {
                LOGE("tcsetattr() failed");
                close(fd);
                /* TODO: throw an exception */
                return NULL;
            }
        }
    
        /* Create a corresponding file descriptor */
        {
            jclass cFileDescriptor = (*env)->FindClass(env, "java/io/FileDescriptor");
            jmethodID iFileDescriptor = (*env)->GetMethodID(env, cFileDescriptor, "<init>", "()V");
            jfieldID descriptorID = (*env)->GetFieldID(env, cFileDescriptor, "descriptor", "I");
            mFileDescriptor = (*env)->NewObject(env, cFileDescriptor, iFileDescriptor);
            (*env)->SetIntField(env, mFileDescriptor, descriptorID, (jint)fd);
        }
    
        return mFileDescriptor;
    }
    
    /* * Class: com_bilibili_www_serialporttest_SerialPort * Method: close * Signature: ()V */
    JNIEXPORT void JNICALL Java_com_bilibili_www_serialporttest_SerialPort_close
        (JNIEnv *env, jobject thiz)
    {
        jclass SerialPortClass = (*env)->GetObjectClass(env, thiz);
        jclass FileDescriptorClass = (*env)->FindClass(env, "java/io/FileDescriptor");
    
        jfieldID mFdID = (*env)->GetFieldID(env, SerialPortClass, "mFd", "Ljava/io/FileDescriptor;");
        jfieldID descriptorID = (*env)->GetFieldID(env, FileDescriptorClass, "descriptor", "I");
    
        jobject mFd = (*env)->GetObjectField(env, thiz, mFdID);
        jint descriptor = (*env)->GetIntField(env, mFd,descriptorID);
    
        LOGD("close(fd = %d)", descriptor);
        close(descriptor);
    }
    
    #ifdef __cplusplus
    
    }
    
    #endif
    
    
  3. module里面的build.gradle

    import com.android.build.gradle.api.AndroidSourceSet
    
    apply plugin: 'com.android.application'
    
    android {
        compileSdkVersion 24
        buildToolsVersion "24.0.0"
        defaultConfig {
            applicationId "com.bilibili.www.serialporttest"
            minSdkVersion 16
            targetSdkVersion 19
            versionCode 1
            versionName "1.0"
            ndk {
                moduleName = "serial_port"
                ldLibs "log", "z", "m", "jnigraphics", "android"
            }
        }
        buildTypes {
            release {
                minifyEnabled false
                proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
                ndk {
                    moduleName = "serial_port"//模块名,要和类SerialPort中的System.loadLibrary();一致
                    ldLibs "log", "z", "m", "jnigraphics", "android"//所要链接的库
                    abiFilters "armeabi", "armeabi-v7a", "x86" //输出指定三种abi体系结构下的so库,目前可有可无。没有的话就生成NDK能生成的所有平台,比如mips
                }
            }
            debug {
                ndk {
                    moduleName = "serial_port"
                    ldLibs "log", "z", "m", "jnigraphics", "android"
                    abiFilters "armeabi", "armeabi-v7a", "x86"
                }
            }
        }
        productFlavors {
        }
    }
    
    dependencies {
        compile fileTree(include: ['*.jar'], dir: 'libs')
        testCompile 'junit:junit:4.12'
        compile 'com.android.support:appcompat-v7:24.0.0'
    }
    
  4. MainActivity
    没有任何布局上的改变,要用控制台查看串口接受信息。这里我使用了接收,需要的话,可以自行添加发送代码。

    package com.bilibili.www.serialporttest;
    
    import android.support.v7.app.AppCompatActivity;
    import android.os.Bundle;
    import android.os.Handler;
    
    import java.io.File;
    import java.io.FileInputStream;
    import java.io.IOException;
    import java.util.Arrays;
    
    import android.util.Log;
    import android.os.Message;
    
    public class MainActivity extends AppCompatActivity { 
         
        private static final String TAG = "MainActivity";
    
        private static final int msgKey = 2;
        private File mFile;
        private FileInputStream mInputStream;
        private SerialPort mSerialPort;
        private ReadThread mThread;
        //private StringBuffer mSb;
        private String mSb;
        private boolean flag = true;
    
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
    
            try {
                mFile=new File("/dev/ttySAC0");
                mSerialPort = new SerialPort(mFile, 115200, 0);
            } catch (SecurityException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            }
    
            mInputStream = (FileInputStream) mSerialPort.getInputStream();
            //启动线程
            mThread = new ReadThread();
            mThread.start();
        }
    
        public  static int searchByte(byte[] data, byte value) {
            int size = data.length;
            for (int i = 0; i < size; ++i) {
                if (data[i] == value) {
                    return i;
                }
            }
            return -1;
        }
    
        public class ReadThread extends Thread { 
         
            @Override
            public void run() {
                // TODO Auto-generated method stub
                super.run();
                while (!isInterrupted()) {
                    int size,couth = 128;
                    try {
    
                        Log.d(TAG, "----ReadThread start----");
                        if (mInputStream == null) {
                            return;
                        }
    
                        /* 获取可以读取的数据长度 */
                        /*for(int coutq1 = mInputStream.available(); coutq1 != couth; coutq1 = mInputStream.available()) { try { sleep(10L); couth = mInputStream.available(); sleep(10L); } catch (InterruptedException e) { e.printStackTrace(); } }*/
    
                        byte[] buffer = new byte[couth];
    
                        Log.d(TAG, "----read(buffer)----");
                        size = mInputStream.read(buffer);
                        Log.d(TAG, "----size----" + String.valueOf(size));
                        if (size > 0) {
                            Log.d(TAG, "----ReadThread size>0----");
                            /*mSb = new StringBuffer(); for (int i = 0; i < buffer.length; i++) { mSb.append(buffer[i]); } Log.d(TAG, "Data=" + mSb.toString());*/
                            mSb=new String(Arrays.copyOfRange(buffer,0,size));
                            Log.d(TAG, "Data=" + mSb);
    
                            Message msg = new Message();
                            msg.what = msgKey;
                            mHandler.sendMessage(msg);
                        }
                        else {
                            Log.d(TAG, "----ReadThread DataisNull----");
                        }
                    } catch (IOException e) {
                        Log.d(TAG, "----ReadThread printStackTrace----");
                        e.printStackTrace();
                        return;
                    }
                }
            }
        }
    
        private Handler mHandler = new Handler() {
            @Override
            public void handleMessage(Message msg) {
                super.handleMessage(msg);
                switch (msg.what) {
                    case msgKey:
                        //Log.e(TAG, mSb.toString());
                        Log.e(TAG, mSb);
                        break;
                    default:
                        break;
                }
            }
        };
    }

编译

  1. Make Project(Ctrl + F9)
  2. <你的工程位置>\app\build\intermediates\ndk\debug\lib目录中,你会发现”armeabi”, “armeabi-v7a”, “x86”三个目录,将他们复制到<你的工程位置>\app\libs中。

运行

GLHF!

问题与经验

  1. 编译没有问题,运行时提示tcgetaddr()函数出现错误,找不到该函数。
    没有把”armeabi”, “armeabi-v7a”, “x86”文件夹放进<你的工程位置>\app\libs中,所以apk不包含这几个文件夹中的so二进制文件,所以出现找不到函数的情况。
    另外一种情况是由于api 19 之后的 termios.h 里面的函数有调整,因此调试过程中,出现

    java.lang.UnsatisfiedLinkError: dlopen failed: cannot locate symbol “tcgetattr” referenced by libserialport.so

    解决方法:

    将api 19 的 termios.h 拷贝到 jni 目录下

    termios.h

     /* * Copyright (C) 2008 The Android Open Source Project * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * * Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in * the documentation and/or other materials provided with the * distribution. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. */
    
    #ifndef _TERMIOS_H_
    
    
    #define _TERMIOS_H_
    
    
    
    #include <sys/cdefs.h>
    
    
    #include <sys/ioctl.h>
    
    
    #include <sys/types.h>
    
    
    #include <stdint.h>
    
    
    #include <linux/termios.h>
    
    
    __BEGIN_DECLS
    
    /* Redefine these to match their ioctl number */
    
    #undef TCSANOW
    
    
    #define TCSANOW TCSETS
    
    
    
    #undef TCSADRAIN
    
    
    #define TCSADRAIN TCSETSW
    
    
    
    #undef TCSAFLUSH
    
    
    #define TCSAFLUSH TCSETSF
    
    
    static __inline__ int tcgetattr(int fd, struct termios *s)
    {
        return ioctl(fd, TCGETS, s);
    }
    
    static __inline__ int tcsetattr(int fd, int __opt, const struct termios *s)
    {
        return ioctl(fd, __opt, (void *)s);
    }
    
    static __inline__ int tcflow(int fd, int action)
    {
        return ioctl(fd, TCXONC, (void *)(intptr_t)action);
    }
    
    static __inline__ int tcflush(int fd, int __queue)
    {
        return ioctl(fd, TCFLSH, (void *)(intptr_t)__queue);
    }
    
    static __inline__ pid_t tcgetsid(int fd)
    {
        pid_t _pid;
        return ioctl(fd, TIOCGSID, &_pid) ? (pid_t)-1 : _pid;
    }
    
    static __inline__ int tcsendbreak(int fd, int __duration)
    {
        return ioctl(fd, TCSBRKP, (void *)(uintptr_t)__duration);
    }
    
    static __inline__ speed_t cfgetospeed(const struct termios *s)
    {
        return (speed_t)(s->c_cflag & CBAUD);
    }
    
    static __inline__ int cfsetospeed(struct termios *s, speed_t  speed)
    {
        s->c_cflag = (s->c_cflag & ~CBAUD) | (speed & CBAUD);
        return 0;
    }
    
    static __inline__ speed_t cfgetispeed(const struct termios *s)
    {
        return (speed_t)(s->c_cflag & CBAUD);
    }
    
    static __inline__ int cfsetispeed(struct termios *s, speed_t  speed)
    {
        s->c_cflag = (s->c_cflag & ~CBAUD) | (speed & CBAUD);
        return 0;
    }
    
    static __inline__ void cfmakeraw(struct termios *s)
    {
        s->c_iflag &= ~(IGNBRK|BRKINT|PARMRK|ISTRIP|INLCR|IGNCR|ICRNL|IXON);
        s->c_oflag &= ~OPOST;
        s->c_lflag &= ~(ECHO|ECHONL|ICANON|ISIG|IEXTEN);
        s->c_cflag &= ~(CSIZE|PARENB);
        s->c_cflag |= CS8;
    }
    
    __END_DECLS
    
    
    #endif /* _TERMIOS_H_ */
    

    然后在c文件中,将#include <termios.h>改为#include "termios.h"

  2. 能运行,但是串口没有反应。
    请检查串口权限,要求other是可读可写的。

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