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USB-KW41Z - FSCI - BLE Notifications not propagated / No NotificationCallback

Question asked by chilipp on Feb 15, 2019
Latest reply on Apr 16, 2019 by chilipp



I'm using the "ble_fsci_blackbox" image with the USB-KW41Z and have a problem with receiving gatt notifications.


The device which the USB-KW41Z is connected to have 2 characteristics, one for data transmission towards the gatt-server (only write permissions) and one for receiving notifications from the gatt-server (only notify permissions).


Now the Problem is, the notification-only characteristics does not have a CCCD to write to / enable notifications as the client is authenticated before (by writing first to the write-only-characteristic) and therefore must be able to handle notifications (gatt server don't have to distinguish whether a client is able to process indications or not - it just sends one if authentication was successful).


While sniffing the BLE traffic I can see a "ATT Handle Value Notification" package on the air from the gatt-server towards the USB-KW41Z, but no NotificationCallback/Indication get triggered.


I registered the "GATTClient-RegisterNotificationCallback.Request" before any GATT operations and also (the GATT-Table is static and I actually know all the handles so first i tried directly writing to the handle) tried first discovering all services/characteristics (I thought, maybe internals need to know about all characteristics to be able to forward notifications on characteristic-handles) but with no success.


I'm expecting "GATTClient-Notification.Indication" but none is received although there is one "in the air".


I'm unable to change the behavior of the gatt-server / unable to implement a CCCD for the characteristic as it's given.