[英]Is there a way to write just a byte in BLE characteristic?
我是Android新手。 我的BLE设备只需要一个字节(标志)。 我尝试只在字节数组中写入一个字节,但是它永远无法正常工作。 在将数组写入期望有2个字节的另一个特性时,该方法起作用。 有什么办法可以解决我的问题,还是必须要求更改设备代码?
我正在以这个项目为例
public void writeCustomCharacteristicStart() {
if (mBluetoothAdapter == null || mBluetoothGatt == null) {
Log.w(TAG, "BluetoothAdapter not initialized");
return;
}
/*check if the service is available on the device*/
BluetoothGattService mCustomService = mBluetoothGatt.getService(UUID.fromString("00001813-0000-1000-8000-00805f9b34fb"));
if(mCustomService == null){
Log.w(TAG, "Custom BLE Service not found");
return;
}
/*get the read characteristic from the service*/
byte pom= 1;
byte[] data= new byte[1];
data[0]=pom;
BluetoothGattCharacteristic mWriteCharacteristic = mCustomService.getCharacteristic(UUID.fromString("00002a4e-0000-1000-8000-00805f9b34fb"));
if((mWriteCharacteristic.getProperties() & BluetoothGattCharacteristic.PROPERTY_WRITE)>0 ) {
Log.w(TAG,"Writing started");
mWriteCharacteristic.setValue(data)
}
if(!mBluetoothGatt.writeCharacteristic(mWriteCharacteristic)){
Log.w(TAG, "Failed to write characteristic");
}
Log.w(TAG,"Writing ending");
}
08-06 11:59:57.700 29279-29279/com.example.devicescanactivity E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.devicescanactivity, PID: 29279
java.lang.IllegalStateException: Could not execute method of the activity
at android.view.View$1.onClick(View.java:4084)
at android.view.View.performClick(View.java:4858)
at android.view.View$PerformClick.run(View.java:20167)
at android.os.Handler.handleCallback(Handler.java:815)
at android.os.Handler.dispatchMessage(Handler.java:104)
at android.os.Looper.loop(Looper.java:194)
at android.app.ActivityThread.main(ActivityThread.java:5931)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:987)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:782)
Caused by: java.lang.reflect.InvocationTargetException
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at android.view.View$1.onClick(View.java:4079)
at android.view.View.performClick(View.java:4858)
at android.view.View$PerformClick.run(View.java:20167)
at android.os.Handler.handleCallback(Handler.java:815)
at android.os.Handler.dispatchMessage(Handler.java:104)
at android.os.Looper.loop(Looper.java:194)
at android.app.ActivityThread.main(ActivityThread.java:5931)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:987)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:782)
Caused by: java.lang.SecurityException: Need BLUETOOTH_PRIVILEGED permission: Neither user 10097 nor current process has android.permission.BLUETOOTH_PRIVILEGED.
at android.os.Parcel.readException(Parcel.java:1549)
at android.os.Parcel.readException(Parcel.java:1502)
at android.bluetooth.IBluetoothGatt$Stub$Proxy.writeCharacteristic(IBluetoothGatt.java:1003)
at android.bluetooth.BluetoothGatt.writeCharacteristic(BluetoothGatt.java:1029)
at com.example.devicescanactivity.BluetoothLeService.writeCustomCharacteristic(BluetoothLeService.java:377)
at com.example.devicescanactivity.DeviceControlActivity.onClickWrite(DeviceControlActivity.java:332)
这是错误,我没有收到BLUETOOTH_PRIVILEGED错误,但是当我写入接受2个字节的特征时,我没有任何错误。
首先,要在您的应用中使用蓝牙,您需要向您的应用清单添加以下权限:
<uses-permission android:name="android.permission.BLUETOOTH" />
<uses-permission android:name="android.permission.BLUETOOTH_ADMIN" />
如果设备期望一个1字节的值,则可以将1个字节的值写入BLE特性。
如果存在长度问题,您应该在onCharacteristicWrite()回调中看到错误:
public void onCharacteristicWrite(BluetoothGatt gatt, BluetoothGattCharacteristic characteristic, int status) {
if (status == BluetoothGatt.GATT_SUCCESS) {
Log.i("TAG", "onCharacteristicWrite() status: " + status + " - UUID: " + characteristic.getUuid());
} else if (status == BluetoothGatt.GATT_INVALID_ATTRIBUTE_LENGTH) {
Log.e("TAG", "onCharacteristicWrite() A write operation failed due to invalid attribute length");
} else {
Log.e("TAG", "onCharacteristicWrite() A write operation failed. Status = " + status);
}
}
另外,我将在您的PROPERTY_WRITE检查中移动writeCharacteristic()调用以确保可以完成写操作:
if((mWriteCharacteristic.getProperties() & BluetoothGattCharacteristic.PROPERTY_WRITE) > 0 ) {
Log.i(TAG,"Writing started");
mWriteCharacteristic.setValue(data)
if(!mBluetoothGatt.writeCharacteristic(mWriteCharacteristic)){
Log.e(TAG, "Failed to write characteristic");
}
}
问题不在于我在特性中写的是我所使用的特性。 我使用了HID控制点,当在计算机上进行nRF Connect应用程序测试时,该设备对我的设备运行良好,但由于其预定义状态,因此无法在android上运行。 我们只是将特性更改为“记录访问控制点”,并且现在可以使用。
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.