Android Question BLE2 activate DataAvailable routine

[Marco Maria Vilucchi]

Hi all,
after connecting to a chip via ble2, I'm trying to talk to him. In the first instance I printed all the characteristics of the service.
Then I wrote a command: "E".
Now I am trying to get an answer, but I have some difficulties.
To activate the DataAvailable routine I need to set:

    manager.SetNotify(ServiceId, C301_risposta, True)

It's true?
previously I have defined the characterisctic:

    C301_risposta= UUID("C301")

UUID is the Erel routine that construct UUID.
The characteristic exists.

But SetNotify has an error:

starter_manager_connected (java line: 470)
java.lang.NullPointerException: Attempt to invoke virtual method 'boolean android.bluetooth.BluetoothGattDescriptor.setValue(byte[])' on a null object reference
    at anywheresoftware.b4a.objects.BleManager2.setNotify(BleManager2.java:322)
    at anywheresoftware.b4a.objects.BleManager2.SetNotify(BleManager2.java:311)
    at com.mamavi.slimup.starter._manager_connected(starter.java:470)
    at java.lang.reflect.Method.invoke(Native Method)
    at anywheresoftware.b4a.BA.raiseEvent2(BA.java:196)
    at anywheresoftware.b4a.BA$2.run(BA.java:370)
    at android.os.Handler.handleCallback(Handler.java:790)
    at android.os.Handler.dispatchMessage(Handler.java:99)
    at android.os.Looper.loop(Looper.java:164)
    at android.app.ActivityThread.main(ActivityThread.java:7000)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:441)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1408)

So far I have always connected with the features of BleCentral (by Erel - ReadChar and WriteChar) and now I need support to use other characteristics.
Now I have near 25 characteristics on the chip and I need to know how manage read, write and DataAvailable.
Does anyone have any examples?
Does anyone know why I get this error?
I have B4A 9.01 and Ble2 1,38
Thanks all
Marcom

 

[Marco Maria Vilucchi]

Can someone help me?

 

[Marco Maria Vilucchi]

follow part of code.

on STARTER module

Private Sub Manager_Connected (Services As List)
    Log("Connected")
    For Each S As String In Services
        Log("Service: " & S)
    Next

    For i=0 To Services.Size-1
        manager.ReadData(Services.Get(i))
    Next
    Log("Proprietà caratteristica 301 "&manager.GetCharacteristicProperties(ServiceId, C301_risposta))

'    manager.SetNotify(ServiceId, ReadChar, True)
'    manager.SetNotify(ServiceId, C301_risposta, True)             THIS LINE IS COMMENTED

    connected = True
    CallSub2(Main, "SetState", connected)
    messagesToSend.Clear
End Sub

Private Sub Manager_DataAvailable (SId As String, Characteristics As Map)
    Log ("Manager_DataAvailable")

    Log(SId)
    For i = 0 To Characteristics.Size - 1
        Log("Key: " & Characteristics.GetKeyAt(i))
        Log("Val: " & Characteristics.GetValueAt(i))
        Dim BC As ByteConverter
        Log("Str: " & BC.StringFromBytes(Characteristics.GetValueAt(i),"utf-8"))
        
        Log("Main.tipomessaggiobluetooth " & Main.tipomessaggiobluetooth)
        Log("Characteristics.GetKeyAt(i) " & Characteristics.GetKeyAt(i))
        If Main.tipomessaggiobluetooth="E" Then
            If Characteristics.GetKeyAt(i)=C303_posizionebilancia Then
                Dim BC As ByteConverter
                MessaggioBluetooth= BC.StringFromBytes(Characteristics.GetValueAt(i),"utf-8")
                LogColor("Main.tipomessaggiobluetooth " & Main.tipomessaggiobluetooth &" Characteristics.GetKeyAt(i) " & Characteristics.GetKeyAt(i) & " MessaggioBluetooth " & MessaggioBluetooth,Colors.blue)
            End If
        End If   
    Next
    Log(" ")
    
'    Dim b() As Byte = Characteristics.Get(C301_risposta)
'    CallSub2(Main, "NewMessage", b)
'    NewMessage(b)
End Sub

Public Sub SendCommand(msg() As Byte)
   LogColor("Dentro SendCommand",Colors.red)
   messagesToSend.Add(TrimMessage(msg))
   If messagesToSend.Size = 1 Then
       Do While messagesToSend.Size > 0
           Try
               manager.WriteData(ServiceId, C300_comando, messagesToSend.Get(0))
           Catch
               FailedToSend
               Return
           End Try
           Wait For Manager_WriteComplete (Characteristic As String, Status As Int)
           If Status <> 0 Then
               FailedToSend
           End If
           If connected = False Or messagesToSend.Size = 0 Then Return
           messagesToSend.RemoveAt(0)
       Loop
   End If
End Sub

on another module:

        Main.tipomessaggiobluetooth="E"
        Main.chichiededellapedana="MisurazioniAltezza"
        Log("misaltezza Main.tipomessaggiobluetooth " & Main.tipomessaggiobluetooth)
'        Dim s As String = "B4A: " & Main.tipomessaggiobluetooth
        Dim s As String = "E"
        CallSub2(Starter, "SendCommand", s.GetBytes("utf8"))

In this way I see on RealTerm that I wrote "E", but I haven't response and DataAvailable doesn't start.

If I uncomment manager.SetNotify(ServiceId, C301_risposta, True)
I have the previous error

starter_manager_connected (java line: 470)
java.lang.NullPointerException: Attempt to invoke virtual method 'boolean android.bluetooth.BluetoothGattDescriptor.setValue(byte[])' on a null object reference
    at anywheresoftware.b4a.objects.BleManager2.setNotify(BleManager2.java:322)
    at anywheresoftware.b4a.objects.BleManager2.SetNotify(BleManager2.java:311)
    at com.mamavi.slimup.starter._manager_connected(starter.java:470)
    at java.lang.reflect.Method.invoke(Native Method)
    at anywheresoftware.b4a.BA.raiseEvent2(BA.java:196)
    at anywheresoftware.b4a.BA$2.run(BA.java:370)
    at android.os.Handler.handleCallback(Handler.java:790)
    at android.os.Handler.dispatchMessage(Handler.java:99)
    at android.os.Looper.loop(Looper.java:164)
    at android.app.ActivityThread.main(ActivityThread.java:7000)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:441)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1408)

How can I do to have a response from chip?
Thanks all
Marco

 

[emexes]

I feel like this burst of read requests could be too much for the BLE device:

For i=0 To Services.Size-1
    manager.ReadData(Services.Get(i))
Next

It is possible that only the first few or last few requests are answered.

Next, I'd add a Log here to confirm that the SetNotify parameters are what you think they are, eg:

Log("SetNotify [" & ServiceId & "] [" & C301_riposta & "]")
manager.SetNotify(ServiceId, C301_risposta, True)

and compare them to what you saw in Nrf Connect, including the upper/lowercaseness.

 

[Marco Maria Vilucchi]

The log is:
SetNotify [0000a002-0000-1000-8000-00805f9b34fb] [0000c301-0000-1000-8000-00805f9b34fb]
on nrf i see: (attached picture)

Error is the same

Is it correct my mode to use SetModify?

 

[emexes]

Characteristic 0000c301-0000-1000-8000-00805f9b34fb is not notifiable.

 

[Marco Maria Vilucchi]

sorry where do you understand it?
Then chip is misconfigured?

 

[emexes]

I've found with BLE that step one is to write the simplest possible app that reads some data.

There is an awful lot that needs to go right, and it only takes one wrong thing for it not to work.

Do you have such an app?

If not, I can send you my first pressure-reading app.

 

[emexes]

sorry where do you understand it?
Then chip is misconfigured?

The characteristics properties are: READ, WRITE

You can read it and write it, but it does not do notifications.

 

[Marco Maria Vilucchi]

Tes plase send me it. I have difficulties to manage characteristics

 

[emexes]

Eg, on this BLE sensor here, I can READ and NOTIFY (stream of readings) the temperature, but I cannot write to it. And I can READ and WRITE the measurement interval, but there is no notify facility for it, because the only time it would change is if I wrote to it.

 

[Marco Maria Vilucchi]

There is a method to read without notify?
If I can have a code to manage these characteristics....

 

[Marco Maria Vilucchi]

There is a method to read without DataAvailable?

 

[emexes]

Which characteristic can you receive data on using nRF?

There is a method to read without notify?

ReadData.

Can you do it from Nrf Connect? Click the single-arrow that points down, next to the characteristic.

 

[emexes]

There is a method to read without DataAvailable?

Not that I know of, although I've never tried.

I always need to do at least one ReadData because it comes back with the Characteristic Ids.

 

[emexes]

Tes plase send me it. I have difficulties to manage characteristics

Sorry about the delay, just wanted to make sure it works here first, then I thought I'll just make one change to make it better...

 

[Marco Maria Vilucchi]

I use readdata to read services

    For i=0 To Services.Size-1
        manager.ReadData(Services.Get(i))
    Next

but how can I read data from characteristics?
I see that only DataAvailable has Characteristics as parameter, but how cha I start DataAvaialble routine?

Please can you give me your base code?

 

[emexes]

I use readdata to read services

For i=0 To Services.Size-1
    manager.ReadData(Services.Get(i))
Next

I think that the above code is issuing too many ReadData requests all at once, and it overwhelms the BLE device. At least, that is what would happen with my BLE pressure sensor - it runs off a battery and is very slow.

but how can I read data from characteristics?
I see that only DataAvailable has Characteristics as parameter, but how cha I start DataAvaialble routine?

When you send a BLE ReadData request, the BLE device should return some data and that will call (start) the DataAvailable routine, with the received data.

 

[emexes]

Please can you give me your base code?

Finally! Attached.

 

[emexes]

The following are the only changes made after I tested it with my BLE device here, to (hopefully) make it work with your device:

'''If Id.EndsWith("9D:0A") Then  
If Id.EndsWith("B9:AA") Then

'''If S.StartsWith("cc4a6a80") Then
If S.StartsWith("0000a002") Then
      
'''If C.StartsWith("835ab4c0") Then
If C.StartsWith("0000c301") Then