status = 4 error when calling requestMtu for twice in Android APP

[Youqun Sun]

Hi,

I am writing Android APP based on nRF Toolbox code.

For the first time to call requestMtu to change MTU to 247, everything works well. We can see the negotiated MTU take effects in both phone and peripheral logs.

Then I try to call requestMtu to change to 27, the APP triggers an error as below:

08-04 17:02:17.622 29981-30007/no.nordicsemi.android.nrftoolbox D/BluetoothGatt: onConfigureMTU() - Device=EC:DD:96:F5:32:BE mtu=247 status=4

08-04 17:02:17.622 29981-30007/no.nordicsemi.android.nrftoolbox E/BleManager: onMtuChanged error: 4, mtu: 247

08-04 17:02:17.625 29981-30007/no.nordicsemi.android.nrftoolbox E/BaseProfileActivity: Error occurred: Error on mtu request, error code: 4

We can locate the error at bleManager.java -> onMtuChanged(), but we can't find the meaning of status = 4.

Can we call requestMtu for multiple times or only once? 

Is there anything wrong in my operation?

Thanks,

Youqun

[Aleksander Nowakowski]

Hi, 

From the Android side you can, but ito Soft Devices allow to change it only once. Had you connected 2 Android phones together, or with Zephyr stack, you could have changed multiple times.

Br,

Aleksander

[Youqun Sun]

Hi,

I don't connect to 2 phones, and test with softdevice stack.

You are right that the softdevice allows only once for mtu request. I think this is the cause.

Thanks,

Youqun