RPi 3 Android Things UART 双向通信使应用程序崩溃

Question

我正在通过 UART 在 RPi 3 运行 Android 之间进行通信 和一个 Arduino.
按下 RPi 应用程序上的按钮后，一条命令将发送到 Arduino。那里没有问题。 Arduino 每 2 秒发送一个信息包。

在我按下一个将数据发送到 Arduino 的按钮之前，这一切都完美无缺。 Arduino 收到按钮命令，但 Android 应用程序崩溃。我什至可以在应用程序崩溃之前按两次按钮，并且 Arduino 成功接收到两次按下。问题似乎是 Arduino 在按下按钮后发送下一个数据包。

如果我断开 RPi UART RX 按钮不会导致崩溃。换句话说，只要没有传入数据，应用程序就可以正常工作，反之亦然。我无法理解错误：

E/AndroidRuntime: FATAL EXCEPTION: main
              Process: za.co.leafbox.boxcontrol, PID: 8817
              java.lang.NumberFormatException: For input string: "pump"
                  at sun.misc.FloatingDecimal.readJavaFormatString(FloatingDecimal.java:2043)
                  at sun.misc.FloatingDecimal.parseFloat(FloatingDecimal.java:122)
                  at java.lang.Float.parseFloat(Float.java:452)
                  at za.co.leafbox.boxcontrol.MainActivity.readUartBuffer(MainActivity.java:284)
                  at za.co.leafbox.boxcontrol.MainActivity.onUartDeviceDataAvailable(MainActivity.java:234)
                  at com.google.android.things.pio.UartDeviceImpl$UartDeviceCallbackDispatch.dispatchInterruptEvent(UartDeviceImpl.java:250)
                  at com.google.android.things.pio.CallbackDispatch.onFileDescriptorEvents(CallbackDispatch.java:149)
                  at android.os.MessageQueue.dispatchEvents(MessageQueue.java:284)
                  at android.os.MessageQueue.nativePollOnce(Native Method)
                  at android.os.MessageQueue.next(MessageQueue.java:325)
                  at android.os.Looper.loop(Looper.java:142)
                  at android.app.ActivityThread.main(ActivityThread.java:6494)
                  at java.lang.reflect.Method.invoke(Native Method)
                  at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438)
                  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:807)

收到的数据示例：

I/MainActivity: [45, 49, 46, 48, 48, 32, 49, 56, 46, 53, 48, 32, 54, 53, 46, 49, 48, 32, 45, 48, 46, 48, 56, 32, 48, 46, 48, 48, 32, 49, 54, 46, 51, 49, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]

OnClick函数：

public void pumpToggle(View view){
    try{
        if (((ToggleButton) view).isChecked()) {
            byte[] buffer = {'g', 'g', '\n'};
            writeUartData(aNano, buffer);
        }
        else{
            byte[] buffer = {'g', 's', '\n'};
            writeUartData(aNano, buffer);
        }

    } catch (IOException e) {
        Log.e(TAG, "Data not Sent", e);
    }
}

UART回调：

private UartDeviceCallback mUartCallback = new UartDeviceCallback() {
    @Override
    public boolean onUartDeviceDataAvailable(UartDevice uart) {
        // Read available data from the UART device
        Log.i(TAG, "onUartDeviceDataAvailable");
        try {
            readUartBuffer(uart);
        } catch (IOException e) {
            Log.w(TAG, "Unable to access UART device", e);
        }
        // Continue listening for more interrupts
        return true;
    }

private void readUartBuffer(UartDevice uart) throws IOException {

    // Maximum amount of data to read at one time
    Log.i(TAG, "readUartBuffer");
    final int maxCount = 64;
    byte[] buffer = new byte[maxCount];
    byte[] convertBuf = new byte[20];
    boolean dataCompleteFlag = false;

    uart.read(buffer, maxCount);

    if (!dataCompleteFlag) {
        for (int i = 0; i < maxCount; i++) {
            if (buffer[i] == 36) {
                dataCompleteFlag = true;
                measureCount++;
                dataCount = 0;
            }
            else if(dataCount > maxCount) {
                dataCount = 0;
            }
            else if(buffer[i] != 0) {
                finalDataBuffer[dataCount] = buffer[i];
                dataCount++;
            }
        }
    }

    if (dataCompleteFlag) {
        Log.i(TAG, Arrays.toString(finalDataBuffer));
        int index = 0;
        int offSet;

        while (index < maxCount && finalDataBuffer[index] != 32) {
            convertBuf[index] = finalDataBuffer[index];
            index++;
        }
        index++;
        offSet = index;

        tankLevelString = new String(convertBuf);
        Float tankFloat = parseFloat(tankLevelString);
        tankLevelString += "cm";

        while (index < maxCount && finalDataBuffer[index] != 32) {
            convertBuf[index - offSet] = finalDataBuffer[index];
            index++;
        }
        index++;
        offSet = index;

        airTempString = new String(convertBuf);
        airTempString += "\u00b0C";

        while (index < maxCount && finalDataBuffer[index] != 32) {
            convertBuf[index - offSet] = finalDataBuffer[index];
            index++;
        }
        index++;
        offSet = index;

        humidityString = new String(convertBuf);
        humidityString += "%";

        while (index < maxCount && finalDataBuffer[index] != 32) {
            convertBuf[index - offSet] = finalDataBuffer[index];
            index++;
        }
        index++;
        offSet = index;

        ecString = new String(convertBuf);

        while (index < maxCount && finalDataBuffer[index] != 32) {
            convertBuf[index - offSet] = finalDataBuffer[index];
            index++;
        }
        index++;
        offSet = index;

        phString = new String(convertBuf);

        while (index < maxCount && finalDataBuffer[index] != 0) {
            convertBuf[index - offSet] = finalDataBuffer[index];
            index++;
        }

        waterTempString = new String(convertBuf);

        TextView airTemp = findViewById(R.id.airTemp);
        airTemp.setText(airTempString);

        TextView humidity = findViewById(R.id.humidity);
        humidity.setText(humidityString);

        TextView tankLevel1 = findViewById(R.id.tankLevel1);
        tankLevel1.setText(tankLevelString);

        TextView ec = findViewById(R.id.ec);
        ec.setText(ecString);

        TextView ph = findViewById(R.id.ph);
        ph.setText(phString);

        TextView wt = findViewById(R.id.waterTemp);
        wt.setText(waterTempString);

    }
}
@Override
public void onUartDeviceError(UartDevice uart, int error) {
    Log.w(TAG, uart + ": Error event " + error);
}
};

Answer 1

parseFloat (tankLevelString) is the line you get the NumberFormatException 上。显然，tankLevelString，也就是"pump"，是无法解析成float的。我建议调查是什么原因造成的。

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