android bluetooth-lowenergy rx-java2 rxandroidble rxbluetooth

BleCharacteristicNotFoundException: Characteristic not found with UUID. How can I get the characteristic UUIDs from a Bluetooth device?

I am unable to retrieve data from my device despite supplying what I believe to be the correct UUID: D/ERROR:: com.polidea.rxandroidble2.exceptions.BleCharacteristicNotFoundException: Characteristic not found with UUID 00001101-0000-1000-8000-00805f9b34fb. What should I do instead?

// Get device from scan
rxBleDevice = scanResult.bleDevice

val deviceUUID = UUID.fromString(scanResult.bleDevice.bluetoothDevice.uuids[0].toString())

// Check device info
println("Name: " + scanResult.bleDevice.name) // Prints to "TestDevice"
println("MAC Address: " + scanResult.bleDevice.macAddress) // Prints to "34:81:F4:3C:2D:7B"
println("UUID = $deviceUUID") // Prints to "00001101-0000-1000-8000-00805f9b34fb"
println("Service UUIDs = " + scanResult.scanRecord.serviceUuids) // Prints to "null"

/* Establish connection to device */
rxBleDevice!!.establishConnection(false) ?
 .doOnNext {
  _ ->
   Log.d("Device: ", "Connection Established")
 } ?
 .flatMapSingle {
  rxBleConnection ->
   deviceUUID? .let {
    rxBleConnection.readCharacteristic(it)
   }
 } ? .subscribe({
  count ->
  // count should be in bytes
  println("SUCCESS: $count")

 }, {
  throwable ->
  Log.d("ERROR: ", "$throwable")
 })

My expected output is a byte array that reads "datc00099", for example.

Solution

The UUID you try to use is from BluetoothDevice.getUuids() which seems to come from "classic" Bluetooth world.

scanResult.scanRecord.serviceUuids may also be null because the UUIDs are not guaranteed to be advertised. Bear in mind that service UUID and characteristic UUID, while having the same format, identify different attributes.

The easiest way to obtain the UUID you are looking for is to ask the peripheral's engineer.

Alternatively, if you know what you are searching for, you can connect to your peripheral, commence a service discovery and search through results. Using this lib in 1.9.0 version it would look like this:

rxBleClient.scanBleDevices(
    ScanSettings.Builder()
        .setScanMode(ScanSettings.SCAN_MODE_LOW_LATENCY)
        .build(),
    ScanFilter.Builder()
        .setDeviceName("TestDevice")
        .build()
)
    .take(1)
    .flatMap { it.bleDevice.establishConnection(false) }
    .flatMapSingle { it.discoverServices() }
    .take(1)
    .subscribe(
        { t -> t.bluetoothGattServices }, // Print services
        { Log.e("ERROR", "WHOOPS!", it) }
    )

Log options should be:

RxBleClient.updateLogOptions(LogOptions.Builder()
        .setLogLevel(LogConstants.VERBOSE)
        .setUuidsLogSetting(LogConstants.UUIDS_FULL)
        .build()

And in your logs you should see something like:

V/RxBle#ServiceDiscoveryOperation: Preparing services description
V/RxBle#ServiceDiscoveryOperation: --------------- ====== Printing peripheral content ====== ---------------
V/RxBle#ServiceDiscoveryOperation: MAC='XX:XX:XX:XX:XX:XX'
V/RxBle#ServiceDiscoveryOperation: PERIPHERAL NAME: SensorTag
V/RxBle#ServiceDiscoveryOperation: -------------------------------------------------------------------------
V/RxBle#ServiceDiscoveryOperation: Primary Service - Generic Access (00001800-0000-1000-8000-00805f9b34fb)
V/RxBle#ServiceDiscoveryOperation: Instance ID: 1
V/RxBle#ServiceDiscoveryOperation: -> Characteristics:
V/RxBle#ServiceDiscoveryOperation:  * Device Name (00002a00-0000-1000-8000-00805f9b34fb)
V/RxBle#ServiceDiscoveryOperation:    Properties: [ READ ]
V/RxBle#ServiceDiscoveryOperation:  * Appearance (00002a01-0000-1000-8000-00805f9b34fb)
V/RxBle#ServiceDiscoveryOperation:    Properties: [ READ ]
V/RxBle#ServiceDiscoveryOperation:  * Peripheral Privacy Flag (00002a02-0000-1000-8000-00805f9b34fb)
V/RxBle#ServiceDiscoveryOperation:    Properties: [ READ WRITE ]
V/RxBle#ServiceDiscoveryOperation:  * Reconnection Address (00002a03-0000-1000-8000-00805f9b34fb)
V/RxBle#ServiceDiscoveryOperation:    Properties: [ WRITE ]
V/RxBle#ServiceDiscoveryOperation:  * Peripheral Preferred Connection Parameters (00002a04-0000-1000-8000-00805f9b34fb)
V/RxBle#ServiceDiscoveryOperation:    Properties: [ READ ]
V/RxBle#ServiceDiscoveryOperation: Primary Service - Generic Attribute (00001801-0000-1000-8000-00805f9b34fb)
V/RxBle#ServiceDiscoveryOperation: Instance ID: 12
V/RxBle#ServiceDiscoveryOperation: -> Characteristics:
V/RxBle#ServiceDiscoveryOperation:  * Service Changed (00002a05-0000-1000-8000-00805f9b34fb)
V/RxBle#ServiceDiscoveryOperation:    Properties: [ INDICATE ]
V/RxBle#ServiceDiscoveryOperation:    -> Descriptors:
V/RxBle#ServiceDiscoveryOperation:      * Client Characteristic Configuration (00002902-0000-1000-8000-00805f9b34fb)
V/RxBle#ServiceDiscoveryOperation: Primary Service - Device Information (0000180a-0000-1000-8000-00805f9b34fb)
V/RxBle#ServiceDiscoveryOperation: Instance ID: 16
V/RxBle#ServiceDiscoveryOperation: -> Characteristics:
V/RxBle#ServiceDiscoveryOperation:  * System ID (00002a23-0000-1000-8000-00805f9b34fb)
V/RxBle#ServiceDiscoveryOperation:    Properties: [ READ ]
V/RxBle#ServiceDiscoveryOperation:  * Model Number String (00002a24-0000-1000-8000-00805f9b34fb)
V/RxBle#ServiceDiscoveryOperation:    Properties: [ READ ]
V/RxBle#ServiceDiscoveryOperation:  * Serial Number String (00002a25-0000-1000-8000-00805f9b34fb)
V/RxBle#ServiceDiscoveryOperation:    Properties: [ READ ]
V/RxBle#ServiceDiscoveryOperation:  * Firmware Revision String (00002a26-0000-1000-8000-00805f9b34fb)
V/RxBle#ServiceDiscoveryOperation:    Properties: [ READ ]
V/RxBle#ServiceDiscoveryOperation:  * Hardware Revision String (00002a27-0000-1000-8000-00805f9b34fb)
V/RxBle#ServiceDiscoveryOperation:    Properties: [ READ ]
V/RxBle#ServiceDiscoveryOperation:  * Software Revision String (00002a28-0000-1000-8000-00805f9b34fb)
V/RxBle#ServiceDiscoveryOperation:    Properties: [ READ ]
V/RxBle#ServiceDiscoveryOperation:  * Manufacturer Name String (00002a29-0000-1000-8000-00805f9b34fb)
V/RxBle#ServiceDiscoveryOperation:    Properties: [ READ ]
V/RxBle#ServiceDiscoveryOperation:  * IEEE 11073-20601 Regulatory Certification Data List (00002a2a-0000-1000-8000-00805f9b34fb)
V/RxBle#ServiceDiscoveryOperation:    Properties: [ READ ]
V/RxBle#ServiceDiscoveryOperation:  * PnP ID (00002a50-0000-1000-8000-00805f9b34fb)
V/RxBle#ServiceDiscoveryOperation:    Properties: [ READ ]
V/RxBle#ServiceDiscoveryOperation: Primary Service - Unknown service (f000aa00-0451-4000-b000-000000000000)
V/RxBle#ServiceDiscoveryOperation: Instance ID: 35
V/RxBle#ServiceDiscoveryOperation: -> Characteristics:
V/RxBle#ServiceDiscoveryOperation:  * Unknown characteristic (f000aa01-0451-4000-b000-000000000000)
V/RxBle#ServiceDiscoveryOperation:    Properties: [ READ NOTIFY ]
V/RxBle#ServiceDiscoveryOperation:    -> Descriptors:
V/RxBle#ServiceDiscoveryOperation:      * Client Characteristic Configuration (00002902-0000-1000-8000-00805f9b34fb)
V/RxBle#ServiceDiscoveryOperation:      * Characteristic User Description (00002901-0000-1000-8000-00805f9b34fb)
V/RxBle#ServiceDiscoveryOperation:  * Unknown characteristic (f000aa02-0451-4000-b000-000000000000)
V/RxBle#ServiceDiscoveryOperation:    Properties: [ READ WRITE ]
V/RxBle#ServiceDiscoveryOperation:    -> Descriptors:
V/RxBle#ServiceDiscoveryOperation:      * Characteristic User Description (00002901-0000-1000-8000-00805f9b34fb)
V/RxBle#ServiceDiscoveryOperation: Primary Service - Unknown service (f000aa10-0451-4000-b000-000000000000)
V/RxBle#ServiceDiscoveryOperation: Instance ID: 43
V/RxBle#ServiceDiscoveryOperation: -> Characteristics:
V/RxBle#ServiceDiscoveryOperation:  * Unknown characteristic (f000aa11-0451-4000-b000-000000000000)
V/RxBle#ServiceDiscoveryOperation:    Properties: [ READ NOTIFY ]
V/RxBle#ServiceDiscoveryOperation:    -> Descriptors:
V/RxBle#ServiceDiscoveryOperation:      * Client Characteristic Configuration (00002902-0000-1000-8000-00805f9b34fb)
V/RxBle#ServiceDiscoveryOperation:      * Characteristic User Description (00002901-0000-1000-8000-00805f9b34fb)
V/RxBle#ServiceDiscoveryOperation:  * Unknown characteristic (f000aa12-0451-4000-b000-000000000000)
V/RxBle#ServiceDiscoveryOperation:    Properties: [ READ WRITE ]
V/RxBle#ServiceDiscoveryOperation:    -> Descriptors:
V/RxBle#ServiceDiscoveryOperation:      * Characteristic User Description (00002901-0000-1000-8000-00805f9b34fb)
V/RxBle#ServiceDiscoveryOperation:  * Unknown characteristic (f000aa13-0451-4000-b000-000000000000)
V/RxBle#ServiceDiscoveryOperation:    Properties: [ READ WRITE ]
V/RxBle#ServiceDiscoveryOperation:    -> Descriptors:
V/RxBle#ServiceDiscoveryOperation:      * Characteristic User Description (00002901-0000-1000-8000-00805f9b34fb)
V/RxBle#ServiceDiscoveryOperation: Primary Service - Unknown service (f000aa20-0451-4000-b000-000000000000)
V/RxBle#ServiceDiscoveryOperation: Instance ID: 54
V/RxBle#ServiceDiscoveryOperation: -> Characteristics:
V/RxBle#ServiceDiscoveryOperation:  * Unknown characteristic (f000aa21-0451-4000-b000-000000000000)
V/RxBle#ServiceDiscoveryOperation:    Properties: [ READ NOTIFY ]
V/RxBle#ServiceDiscoveryOperation:    -> Descriptors:
V/RxBle#ServiceDiscoveryOperation:      * Client Characteristic Configuration (00002902-0000-1000-8000-00805f9b34fb)
V/RxBle#ServiceDiscoveryOperation:      * Characteristic User Description (00002901-0000-1000-8000-00805f9b34fb)
V/RxBle#ServiceDiscoveryOperation:  * Unknown characteristic (f000aa22-0451-4000-b000-000000000000)
V/RxBle#ServiceDiscoveryOperation:    Properties: [ READ WRITE ]
V/RxBle#ServiceDiscoveryOperation:    -> Descriptors:
V/RxBle#ServiceDiscoveryOperation:      * Characteristic User Description (00002901-0000-1000-8000-00805f9b34fb)
V/RxBle#ServiceDiscoveryOperation: Primary Service - Unknown service (f000aa30-0451-4000-b000-000000000000)
V/RxBle#ServiceDiscoveryOperation: Instance ID: 62
V/RxBle#ServiceDiscoveryOperation: -> Characteristics:
V/RxBle#ServiceDiscoveryOperation:  * Unknown characteristic (f000aa31-0451-4000-b000-000000000000)
V/RxBle#ServiceDiscoveryOperation:    Properties: [ READ NOTIFY ]
V/RxBle#ServiceDiscoveryOperation:    -> Descriptors:
V/RxBle#ServiceDiscoveryOperation:      * Client Characteristic Configuration (00002902-0000-1000-8000-00805f9b34fb)
V/RxBle#ServiceDiscoveryOperation:      * Characteristic User Description (00002901-0000-1000-8000-00805f9b34fb)
V/RxBle#ServiceDiscoveryOperation:  * Unknown characteristic (f000aa32-0451-4000-b000-000000000000)
V/RxBle#ServiceDiscoveryOperation:    Properties: [ READ WRITE ]
V/RxBle#ServiceDiscoveryOperation:    -> Descriptors:
V/RxBle#ServiceDiscoveryOperation:      * Characteristic User Description (00002901-0000-1000-8000-00805f9b34fb)
V/RxBle#ServiceDiscoveryOperation:  * Unknown characteristic (f000aa33-0451-4000-b000-000000000000)
V/RxBle#ServiceDiscoveryOperation:    Properties: [ READ WRITE ]
V/RxBle#ServiceDiscoveryOperation:    -> Descriptors:
V/RxBle#ServiceDiscoveryOperation:      * Characteristic User Description (00002901-0000-1000-8000-00805f9b34fb)
V/RxBle#ServiceDiscoveryOperation: Primary Service - Unknown service (f000aa40-0451-4000-b000-000000000000)
V/RxBle#ServiceDiscoveryOperation: Instance ID: 73
V/RxBle#ServiceDiscoveryOperation: -> Characteristics:
V/RxBle#ServiceDiscoveryOperation:  * Unknown characteristic (f000aa41-0451-4000-b000-000000000000)
V/RxBle#ServiceDiscoveryOperation:    Properties: [ READ NOTIFY ]
V/RxBle#ServiceDiscoveryOperation:    -> Descriptors:
V/RxBle#ServiceDiscoveryOperation:      * Client Characteristic Configuration (00002902-0000-1000-8000-00805f9b34fb)
V/RxBle#ServiceDiscoveryOperation:      * Characteristic User Description (00002901-0000-1000-8000-00805f9b34fb)
V/RxBle#ServiceDiscoveryOperation:  * Unknown characteristic (f000aa42-0451-4000-b000-000000000000)
V/RxBle#ServiceDiscoveryOperation:    Properties: [ READ WRITE ]
V/RxBle#ServiceDiscoveryOperation:    -> Descriptors:
V/RxBle#ServiceDiscoveryOperation:      * Characteristic User Description (00002901-0000-1000-8000-00805f9b34fb)
V/RxBle#ServiceDiscoveryOperation:  * Unknown characteristic (f000aa43-0451-4000-b000-000000000000)
V/RxBle#ServiceDiscoveryOperation:    Properties: [ READ ]
V/RxBle#ServiceDiscoveryOperation:    -> Descriptors:
V/RxBle#ServiceDiscoveryOperation:      * Client Characteristic Configuration (00002902-0000-1000-8000-00805f9b34fb)
V/RxBle#ServiceDiscoveryOperation:      * Characteristic User Description (00002901-0000-1000-8000-00805f9b34fb)
V/RxBle#ServiceDiscoveryOperation: Primary Service - Unknown service (f000aa50-0451-4000-b000-000000000000)
V/RxBle#ServiceDiscoveryOperation: Instance ID: 85
V/RxBle#ServiceDiscoveryOperation: -> Characteristics:
V/RxBle#ServiceDiscoveryOperation:  * Unknown characteristic (f000aa51-0451-4000-b000-000000000000)
V/RxBle#ServiceDiscoveryOperation:    Properties: [ READ NOTIFY ]
V/RxBle#ServiceDiscoveryOperation:    -> Descriptors:
V/RxBle#ServiceDiscoveryOperation:      * Client Characteristic Configuration (00002902-0000-1000-8000-00805f9b34fb)
V/RxBle#ServiceDiscoveryOperation:      * Characteristic User Description (00002901-0000-1000-8000-00805f9b34fb)
V/RxBle#ServiceDiscoveryOperation:  * Unknown characteristic (f000aa52-0451-4000-b000-000000000000)
V/RxBle#ServiceDiscoveryOperation:    Properties: [ READ WRITE ]
V/RxBle#ServiceDiscoveryOperation:    -> Descriptors:
V/RxBle#ServiceDiscoveryOperation:      * Characteristic User Description (00002901-0000-1000-8000-00805f9b34fb)
V/RxBle#ServiceDiscoveryOperation: Primary Service - Unknown service (0000ffe0-0000-1000-8000-00805f9b34fb)
V/RxBle#ServiceDiscoveryOperation: Instance ID: 93
V/RxBle#ServiceDiscoveryOperation: -> Characteristics:
V/RxBle#ServiceDiscoveryOperation:  * Unknown characteristic (0000ffe1-0000-1000-8000-00805f9b34fb)
V/RxBle#ServiceDiscoveryOperation:    Properties: [ NOTIFY ]
V/RxBle#ServiceDiscoveryOperation:    -> Descriptors:
V/RxBle#ServiceDiscoveryOperation:      * Client Characteristic Configuration (00002902-0000-1000-8000-00805f9b34fb)
V/RxBle#ServiceDiscoveryOperation:      * Characteristic User Description (00002901-0000-1000-8000-00805f9b34fb)
V/RxBle#ServiceDiscoveryOperation: Primary Service - Unknown service (f000aa60-0451-4000-b000-000000000000)
V/RxBle#ServiceDiscoveryOperation: Instance ID: 98
V/RxBle#ServiceDiscoveryOperation: -> Characteristics:
V/RxBle#ServiceDiscoveryOperation:  * Unknown characteristic (f000aa61-0451-4000-b000-000000000000)
V/RxBle#ServiceDiscoveryOperation:    Properties: [ READ ]
V/RxBle#ServiceDiscoveryOperation:    -> Descriptors:
V/RxBle#ServiceDiscoveryOperation:      * Characteristic User Description (00002901-0000-1000-8000-00805f9b34fb)
V/RxBle#ServiceDiscoveryOperation:  * Unknown characteristic (f000aa62-0451-4000-b000-000000000000)
V/RxBle#ServiceDiscoveryOperation:    Properties: [ READ WRITE ]
V/RxBle#ServiceDiscoveryOperation:    -> Descriptors:
V/RxBle#ServiceDiscoveryOperation:      * Characteristic User Description (00002901-0000-1000-8000-00805f9b34fb)
V/RxBle#ServiceDiscoveryOperation: Primary Service - Unknown service (f000ccc0-0451-4000-b000-000000000000)
V/RxBle#ServiceDiscoveryOperation: Instance ID: 105
V/RxBle#ServiceDiscoveryOperation: -> Characteristics:
V/RxBle#ServiceDiscoveryOperation:  * Unknown characteristic (f000ccc1-0451-4000-b000-000000000000)
V/RxBle#ServiceDiscoveryOperation:    Properties: [ READ NOTIFY ]
V/RxBle#ServiceDiscoveryOperation:    -> Descriptors:
V/RxBle#ServiceDiscoveryOperation:      * Client Characteristic Configuration (00002902-0000-1000-8000-00805f9b34fb)
V/RxBle#ServiceDiscoveryOperation:      * Characteristic User Description (00002901-0000-1000-8000-00805f9b34fb)
V/RxBle#ServiceDiscoveryOperation:  * Unknown characteristic (f000ccc2-0451-4000-b000-000000000000)
V/RxBle#ServiceDiscoveryOperation:    Properties: [ WRITE ]
V/RxBle#ServiceDiscoveryOperation:    -> Descriptors:
V/RxBle#ServiceDiscoveryOperation:      * Characteristic User Description (00002901-0000-1000-8000-00805f9b34fb)
V/RxBle#ServiceDiscoveryOperation:  * Unknown characteristic (f000ccc3-0451-4000-b000-000000000000)
V/RxBle#ServiceDiscoveryOperation:    Properties: [ WRITE ]
V/RxBle#ServiceDiscoveryOperation:    -> Descriptors:
V/RxBle#ServiceDiscoveryOperation:      * Characteristic User Description (00002901-0000-1000-8000-00805f9b34fb)
V/RxBle#ServiceDiscoveryOperation: Primary Service - Unknown service (f000ffc0-0451-4000-b000-000000000000)
V/RxBle#ServiceDiscoveryOperation: Instance ID: 116
V/RxBle#ServiceDiscoveryOperation: -> Characteristics:
V/RxBle#ServiceDiscoveryOperation:  * Unknown characteristic (f000ffc1-0451-4000-b000-000000000000)
V/RxBle#ServiceDiscoveryOperation:    Properties: [ WRITE_NO_RESPONSE WRITE NOTIFY ]
V/RxBle#ServiceDiscoveryOperation:    -> Descriptors:
V/RxBle#ServiceDiscoveryOperation:      * Client Characteristic Configuration (00002902-0000-1000-8000-00805f9b34fb)
V/RxBle#ServiceDiscoveryOperation:      * Characteristic User Description (00002901-0000-1000-8000-00805f9b34fb)
V/RxBle#ServiceDiscoveryOperation:  * Unknown characteristic (f000ffc2-0451-4000-b000-000000000000)
V/RxBle#ServiceDiscoveryOperation:    Properties: [ WRITE_NO_RESPONSE WRITE NOTIFY ]
V/RxBle#ServiceDiscoveryOperation:    -> Descriptors:
V/RxBle#ServiceDiscoveryOperation:      * Client Characteristic Configuration (00002902-0000-1000-8000-00805f9b34fb)
V/RxBle#ServiceDiscoveryOperation:      * Characteristic User Description (00002901-0000-1000-8000-00805f9b34fb)
V/RxBle#ServiceDiscoveryOperation: --------------- ====== Finished peripheral content ====== ---------------

Characteristic UUIDs are provided in brackets. You would just need to find the one you are looking for.