为什么按下一个按钮触发处理程序

Question

我在Raspberry Pi上运行Android Things 0.4.我正在按照这个教程写信:

https://developer.android.com/things/training/first-device/peripherals.html

一旦我按下第一个按钮,我就决定在继续学习本教程的led部分之前添加第二个按钮.我知道硬件设置对于第一个按钮是正确的,所以我在第二个按钮上复制了它,但是由于某种原因我无法理解按钮没有按预期运行.第一个按钮触发两个按钮的事件侦听器.第二个按钮将触发一个方向,并且在按下第二个按钮后按下第一个按钮之前不会再次触发.

我是一位经验丰富的Android开发人员,但对IoT和Things来说却是新手.这是我的代码:

public class MainActivity extends Activity {
private static final String TAG = "ButtonActivity";
private static final String INC_BUTTON_PIN_NAME = "BCM4"; // GPIO port wired to the button
private static final String DEC_BUTTON_PIN_NAME = "BCM17"; // GPIO port wired to the button

private Gpio mIncButtonGpio;
private Gpio mDecButtonGpio;

Handler mHandler = new Handler(Looper.getMainLooper());

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    PeripheralManagerService service = new PeripheralManagerService();
    try {
        // Step 1. Create GPIO connection.
        mIncButtonGpio = service.openGpio(INC_BUTTON_PIN_NAME);
        mDecButtonGpio = service.openGpio(DEC_BUTTON_PIN_NAME);
        // Step 2. Configure as an input.
        mIncButtonGpio.setDirection(Gpio.DIRECTION_IN);
        mDecButtonGpio.setDirection(Gpio.DIRECTION_IN);
        // Step 3. Enable edge trigger events.
        mIncButtonGpio.setEdgeTriggerType(Gpio.EDGE_FALLING);
        mDecButtonGpio.setEdgeTriggerType(Gpio.EDGE_FALLING);
        // Step 4. Register an event callback.
        mIncButtonGpio.registerGpioCallback(mIncCallback);
        mDecButtonGpio.registerGpioCallback(mDecCallback);
    } catch (IOException e) {
        Log.e(TAG, "Error on PeripheralIO API", e);
    }
}

// Step 4. Register an event callback.
private GpioCallback mIncCallback = new GpioCallback() {
    @Override
    public boolean onGpioEdge(Gpio gpio) {
        Log.i(TAG, "GPIO changed, INC button pressed");

        // Step 5. Return true to keep callback active.
        return true;
    }
};

private GpioCallback mDecCallback = new GpioCallback() {
    @Override
    public boolean onGpioEdge(Gpio gpio) {
        Log.i(TAG, "GPIO changed, DEC button pressed");

        // Step 5. Return true to keep callback active.
        return true;
    }
};

@Override
protected void onDestroy() {
    super.onDestroy();

    // Step 6. Close the resource
    if (mIncButtonGpio != null) {
        mIncButtonGpio.unregisterGpioCallback(mIncCallback);
        try {
            mIncButtonGpio.close();
        } catch (IOException e) {
            Log.e(TAG, "Error on PeripheralIO API", e);
        }
    }
    if (mDecButtonGpio != null) {
        mDecButtonGpio.unregisterGpioCallback(mDecCallback);
        try {
            mDecButtonGpio.close();
        } catch (IOException e) {
            Log.e(TAG, "Error on PeripheralIO API", e);
        }
    }
}
}

按下第一个按钮1次后,这是我的logcat:

06-09 14:33:21.717 1393-1393/com.maddesa.iottest I/ButtonActivity: GPIO changed, INC button pressed
06-09 14:33:21.718 1393-1393/com.maddesa.iottest I/ButtonActivity: GPIO changed, DEC button pressed

这是在第一个按下第二个按钮之后:

06-09 14:33:21.717 1393-1393/com.maddesa.iottest I/ButtonActivity: GPIO changed, INC button pressed
06-09 14:33:21.718 1393-1393/com.maddesa.iottest I/ButtonActivity: GPIO changed, DEC button pressed
06-09 14:33:58.047 1393-1393/com.maddesa.iottest I/ButtonActivity: GPIO changed, DEC button pressed

如果我按下第一个按钮,然后按第二个按钮,然后再次按第一个按钮,它就像是这样:

06-09 14:39:06.804 1393-1393/com.maddesa.iottest I/ButtonActivity: GPIO changed, INC button pressed
06-09 14:39:06.804 1393-1393/com.maddesa.iottest I/ButtonActivity: GPIO changed, DEC button pressed
06-09 14:39:08.846 1393-1393/com.maddesa.iottest I/ButtonActivity: GPIO changed, DEC button pressed
06-09 14:39:11.377 1393-1393/com.maddesa.iottest I/ButtonActivity: GPIO changed, INC button pressed
06-09 14:39:11.377 1393-1393/com.maddesa.iottest I/ButtonActivity: GPIO changed, DEC button pressed
06-09 14:39:11.510 1393-1393/com.maddesa.iottest I/ButtonActivity: GPIO changed, INC button pressed
06-09 14:39:11.510 1393-1393/com.maddesa.iottest I/ButtonActivity: GPIO changed, DEC button pressed

就像我说的我对物联网和物联网的新手一样,但我只想拥有两个独立的按钮,它们始终触发单独的处理程序.

谢谢.

Answer 1

您需要在接地线上放置一些二极管，以防止信号反向传播。当您按下其中一个按钮时，接地会使另一个按钮短路。

当您按下顶部按钮时，电流将流向地线（红线），向下到达向下按钮的白线。它从白色线穿过电阻器，然后通过橙色线回到 GPIO 7。