I'm trying to implement BLE application in Xamarin forms. But the read operation gives me exception even though I gave permission for read in peripheral.
{Plugin.BLE.Abstractions.Exceptions.CharacteristicReadException: Read async error: Error Domain=CBATTErrorDomain Code=1 "The handle is invalid." UserInfo={NSLocalizedDescription=The handle is invalid.}
This is my BLE code
private async Task<string> ProcessDeviceInformationService(IService deviceInfoService)
{
try
{
await adapter.ConnectToDeviceAsync(device);
var sb = new StringBuilder("Getting information from Device Information service: \n");
var characteristics = deviceInfoService.GetCharacteristicsAsync();
var characteristic = await deviceInfoService.GetCharacteristicAsync(Guid.Parse("00002B0F-0000-1000-8000-00805F9B34FB"));
try
{
if (characteristic != null)
{
var sbnew = new StringBuilder("BLE Characteristics\n");
byte[] senddata = Encoding.UTF8.GetBytes(string.IsNullOrEmpty(SendMessageLabel.Text) ? "12" : SendMessageLabel.Text);
MainThread.BeginInvokeOnMainThread(async () =>
{
characteristic.ValueUpdated += (o, args) =>
{
var bytes = characteristic.Value;
};
await characteristic.WriteAsync(senddata);
string str = Encoding.UTF8.GetString(senddata);
sbnew.AppendLine($"Characteristics found on this device: {string.Join(", ", str.ToString())}");
CharactericsLabel.Text = sbnew.ToString();
}
}
catch (Exception ex)
{
//return ex.Message;
DisplayAlert("Notice", ex.Message.ToString(), "OK");
}
This is the code of my peripheral
// Current Time characteristic
BluetoothGattCharacteristic currentTime = new BluetoothGattCharacteristic(CURRENT_TIME,
//Read-only characteristic, supports notifications
BluetoothGattCharacteristic.PROPERTY_READ | BluetoothGattCharacteristic.PROPERTY_NOTIFY | BluetoothGattCharacteristic.PROPERTY_WRITE_NO_RESPONSE,
BluetoothGattCharacteristic.PERMISSION_READ | BluetoothGattCharacteristic.PROPERTY_WRITE);
BluetoothGattDescriptor configDescriptor = new BluetoothGattDescriptor(CLIENT_CONFIG,
//Read/write descriptor
BluetoothGattDescriptor.PERMISSION_READ | BluetoothGattDescriptor.PERMISSION_WRITE);
currentTime.addDescriptor(configDescriptor);
// Local Time Information characteristic
BluetoothGattCharacteristic localTime = new BluetoothGattCharacteristic(LOCAL_TIME_INFO,
//Read-only characteristic
BluetoothGattCharacteristic.PROPERTY_READ,
BluetoothGattCharacteristic.PERMISSION_READ);
BluetoothGattCharacteristic sampleText = new BluetoothGattCharacteristic(SAMPLE_TEXT,
//Read-only characteristic
BluetoothGattCharacteristic.PROPERTY_WRITE_NO_RESPONSE | BluetoothGattCharacteristic.PROPERTY_READ | BluetoothGattCharacteristic.PROPERTY_NOTIFY,
BluetoothGattCharacteristic.PERMISSION_WRITE | BluetoothGattCharacteristic.PERMISSION_READ);
I'm using characteristic sampleText.I'm using Plugin.Ble 2.0.1 latest version and iOS version 14.0 . I have no clue how to fix this any suggestions.