Subscribing to notification changes with RxBLe Android

Question

I'm trying to subscribe to notification changes from a BLE device that I built, and print the value of the notification. I know the characteristic UUID that I want to read the notifications from:

scanSubscription = rxBleClient.scanBleDevices(
        ScanSettings.Builder().build(),
        ScanFilter.Builder().setDeviceName("MyDevice").build() // Filter for devices named MyDevice
    )
    .take(1) // stop the scan when a matching device will be scanned for the first time
    .flatMap {
        val device = it.bleDevice
        device.establishConnection(false)
            .flatMap < Any > {
                rxBleConnection: RxBleConnection - > rxBleConnection.setupNotification(charUUID)
            }
            .doOnNext {
                notificationObservable: Any ? - >
            }
            .flatMap < Any > {
                notificationObservable: Any ? - > notificationObservable
            } // <-- Notification has been set up, now observe value changes.

    }
    .subscribe({ /* written */ }, {
        throwable - >
        // Handle an error here.
        // println("Scan Error: $throwable")
    })

To prove that the device is working as intended, I observe the notification changes using the BLE Scanner app for Android.

When I wave my hand over the sensor, the value changes. In my case, it increments.

My question is how can I print that value when the notification value changes? When debugging, I can't get the Count to print. It doesn't even appear in my console.

BLE related tags look irrelevant for this question as you do not have issues with BLE. — Marcin Orlowski, Jul 06 '20 at 00:55

score 1 · Accepted Answer · answered Jul 06 '20 at 08:09

Usually on Android one uses Log class to log data to logcat. You could use it like this:

scanSubscription = rxBleClient.scanBleDevices(
        ScanSettings.Builder().build(),
        ScanFilter.Builder().setDeviceName("MyDevice").build() // Filter for devices named MyDevice
    )
    .take(1) // stop the scan when a matching device will be scanned for the first time
    .flatMap {
        val device = it.bleDevice
        device.establishConnection(false)
            .flatMap < Any > {
                rxBleConnection: RxBleConnection - > rxBleConnection.setupNotification(charUUID)
            }
            .doOnNext {
                notificationObservable: Any ? - >
            }
            .flatMap < Any > {
                notificationObservable: Any ? - > notificationObservable
            } // <-- Notification has been set up, now observe value changes.

    }
    .subscribe(
        { notification -> Log.i("Notification!", notification.contentToString()) }, 
        { throwable -> Log.e("Whoops!", "Scan Error", throwable) }
    )

Subscribing to notification changes with RxBLe Android

1 Answers1