Android Question iTAG BLE Button now is not working


Active Member
Licensed User
Hi, folks. Please help me with your wisdom :D

I developed years ago an App to work with the button of iTAG, but apparently, something is different with the new iTags.

For troubleshooting, I used the nRF Connect App. and I noticed I need to send a command or similar to the iTAG to enable the feature of the button. my old iTAGs work without need to write or send something to them. But these new ones are weirds.

the New iTAG and nRF Connect. The new iTAG is connected
Take a look at "Notification and Indication disable"
if I press the button in the iTAG the nRF does not detect it.


So, to put to work the button of the iTAG I did this:
Pressed the button (I showed in blue circle).
and look now the value to "Notification Enable"


So, Now when I press the iTAG button the nRF connect App receive the value take a look the green circle the value is correct (0x)01 exactly the same with my old iTAGs


My understanding, apparently, I need now with those new iTags send a manager.write or manager.notify to enable or turn on the flag indicating the iTAG to send the value 0x01 ??? with the old iTAG I only need read never send a command. :eek:

Sub Manager_DataAvailable (ServiceId As String, Characteristics As Map)
'iTags only
    Dim Valread As String = ""
    For Each id As String In Characteristics.Keys
        Dim data() As Byte
        data = Characteristics.Get(id)
        Valread  = BytesToString(data, 0, data.Length, "UTF8")
        Select id
            Case findmeCharacteristic    'FIND_ME_CHARACTERISTIC     
                BotoniTAGapretado = data(0)   '1   = Button Pressed    0 = No button pressed.
Dim findmeCharacteristic As String = "0000ffe1-0000-1000-8000-00805f9b34fb"
Dim findmeService As String = "0000ffe0-0000-1000-8000-00805f9b34fb"

That code works great with my old iTags, but give this error with the new ones.

Found: ITAG, FC:58:FA:04:03:DB, RSSI = -64, (MyMap) {1=[B@424587b, 10=[B@915698, 2=[B@7d45ef1, 9=[B@9c00ad6, 0=[B@1960157}
Discovering services.
Discovering services.
Discovering services.
id =00002a05-0000-1000-8000-00805f9b34fbCaracteristica =[B@cd395c8
id =00002a06-0000-1000-8000-00805f9b34fbCaracteristica =[B@e69e661
id =0000ffe1-0000-1000-8000-00805f9b34fbCaracteristica =[B@74ed586
nucleo_manager_dataavailable (B4A line: 207)
BotoniTAGapretado = data(0) '1 = Button Pressed
java.lang.ArrayIndexOutOfBoundsException: length=0; index=0
at cpn.dgcop.nucleo5._manager_dataavailable(
at java.lang.reflect.Method.invoke(Native Method)
at anywheresoftware.b4a.BA.raiseEvent2(
at anywheresoftware.b4a.BA$
at android.os.Handler.handleCallback(
at android.os.Handler.dispatchMessage(
at android.os.Looper.loop(
at java.lang.reflect.Method.invoke(Native Method)

The problematic code is this:
BotoniTAGapretado = data(0) '1 = Button Pressed 0 = No button pressed

I am thinking, I am close to the solution but :confused:

Thanks for any light.

Daniel W
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Well-Known Member
Licensed User
I do love those iTags, especially now that they're like a buck each, but I too noticed that they are not identical.

I wish they transmitted the button status as part of the advertising packet, that'd be so much easier than having to connect to them.

Anyway, in your case above, it does look like that characteristic can only be accessed using notify, because I'm pretty sure I see the phrase "READ NOTIFY" a lot, but in your screenshots it's just showing "NOTIFY" ie no read.

And just to make sure that you use the notify method, it seems the manufacturer has neutered the read method to not return any data ie a 0 length array, from which you are trying to extract data anyway, hence the array out of bounds.

Perhaps the manufacturer is trying to make their iTags different to other manufacturers' in order to prevent their software being used with other iTags. Or perhaps it's just a programming slipup.

Right, now I'll actually grab nrF Connect and a few iTags here and confirm what I just wrote ;-)
Last edited:


Well-Known Member
Licensed User
I have three iTags, of two varieties (judging by the Bluetooth Ids), and they all show "READ NOTIFY" in nRF Connect.

So I think an immediate solution for your case might be something like:
Sub Manager_DataAvailable(ServiceID As String, Characteristics As Map)
    if ServiceID.CompareTo(ButtonService) then
        Dim SetNotifyFlag As Boolean = True    'if no button data received, then enable notifications

        Dim ButtonData as Object = Characteristics.Get(ButtonCharacteristic)
        If ButtonData <> Null then
            Dim TempByteArray() As Byte = ButtonData
            If TempByteArray.Length > 0 Then
                ButtonState = TempByteArray(0)
                SetNotifyFlag = False    'button data received, no need to (re)enable notifications
            End If
        End If

        If SetNotifyFlag Then
            manager.SetNotify(ButtonService, ButtonCharacteristic, True)
        End If
    End If
End Sub
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