串口通信

Chip Platform Rockchip
1

我仿android-serial-api做的串口通信APP，对ttyS0~3进行读写操作发现并不能对ttyS0~3存取数据。
jni的代码

JNIEXPORT jobject JNICALL Java_com_example_liangzhanpeng_urat_SerialPort_open
  (JNIEnv *env, jclass thiz, jstring path, jint baudrate){
    int fd;
    speed_t speed;
    jclass mFileDescriptor;
    {
    speed = getBaudrate(baudrate);
    if (speed == -1){
    LOGE("invalid baudrate");
    return NULL;
    }
    }

    {
        jboolean iscopy;
        const char *path_utf = (*env)->GetStringUTFChars(env, path, &iscopy);

        LOGE("OPENING SERIAL PORT %s",path_utf);

        fd = open(path_utf,O_RDWR | O_NOCTTY | O_NONBLOCK | O_NDELAY);
        LOGD("open() fd = %d", fd);
        (*env)->ReleaseStringUTFChars(env,path,path_utf);
        if(fd == -1)
        {
            LOGE("cannot open port");
            return NULL;
        }
    }

    {
        struct termios cfg;
        LOGD("Configuring serial port");
        if(tcgetattr(fd,&cfg))
        {
            LOGE("tcgetattr() failed");
            close(fd);
            return NULL;
        }

        cfmakeraw(&cfg);
        cfsetispeed(&cfg,speed);
        cfsetospeed(&cfg,speed);

        if(tcsetattr(fd,TCSANOW,&cfg))
        {
            LOGE("tcsetattr() failed");
            close(fd);
            return NULL;
        }
    }
    {
        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;
  }

串口操作代码为

 private FileDescriptor mfd;
    private FileInputStream mFileInputStream;
    private FileOutputStream outputStreaml;

    public SerialPort(File device,int baudrate) throws SecurityException,IOException{
        if (!device.canRead() || !device.canWrite()){
            try{
                Process su;
                su = Runtime.getRuntime().exec("/system/xbin/su");

                Log.i(TAG, "SerialPort: "+su.toString());
                String cmd = "chmod 777 " + device.getAbsolutePath() + "\n" + "exit\n";
                Log.i(TAG, "SerialPort: " + cmd.toString());
                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.i(TAG, "SerialPort is can read?"+device.canRead());
        Log.i(TAG,"SerialPort is can writter" + device.canWrite());
        mfd = open(device.getAbsolutePath(),baudrate);
        if(mfd == null){
            Log.e(TAG,"native open return null");

        }
        Log.i(TAG, "SerialPort>>>"+ mfd);
        mFileInputStream = new FileInputStream(mfd);
        outputStreaml = new FileOutputStream(mfd);
    }
    public InputStream getInputStream(){
        return mFileInputStream;
    }
    public OutputStream getOutputStream(){
        return outputStreaml;
    }
    private native static FileDescriptor open(String path, int baudrate);
    public native void close();
    static {
        System.loadLibrary("serialport");
    }

MainActivity代码为

 public void onClick(View view) {
        switch (view.getId()){
            case R.id.setup:

            try{
                sp = new SerialPort(new File("/dev/ttyS0"),115200);
            }catch (SecurityException e){
                e.printStackTrace();
            }catch (IOException e){
                e.printStackTrace();
            }
                fileInputStream = sp.getInputStream();
                fileOutputStream = sp.getOutputStream();
                break;
            case R.id.send:
                try {
                    String str = "abc123";
                    byte[] a = str.getBytes();
                    byte b = 1;
                    Log.i(TAG, "send>>> "+a[0]+a[1]+a[2]);
                    fileOutputStream.write(a);
                    fileOutputStream.write('\n');
                } catch (IOException e) {
                    e.printStackTrace();
                }

                Toast.makeText(getApplicationContext(), "send",
                        Toast.LENGTH_SHORT).show();
                break;
            case R.id.recevicd:
                int size;

                try {
                    byte[] test = new byte[64];
                    fileInputStream.read(test);

                    byte[] buffer = new byte[64];
                    if (fileInputStream == null)
                        return;
                    Log.i(TAG, "onClick: "+ buffer.length);
                    Log.i(TAG, "recevied"+buffer.toString());
                    size = fileInputStream.read(buffer);
                    Log.i(TAG, "size>>>"+size);
                    if (size > 0) {
                        onDataReceived(buffer, size);

                    }
                } catch (IOException e) {
                    e.printStackTrace();
                    return;
                }

        }

    }
    void onDataReceived(final byte[] buffer, final int size) {
        runOnUiThread(new Runnable() {
            public void run() {
                if (editText != null) {
                    Log.i(TAG, "run: "+new String(buffer, 0, size));
                    textView.setText(new String(buffer, 0, size));
                }
            }
        });
    }