BLE - gatt caching

[Roei]

Hi, We are using nrf52840 with BLE device which is connecting to a mobile phone. The first pairing requires password to create the bonding.

the connection seems to be stable the first time it connects.

once the device is disconnected and attempts to reconnect after a few seconds or days it seems like the connection is not stable and gets disconnected after a few seconds or minutes.

From a quick research in the net I have found some developers that say it has to be something that is related to the mobile phone BLE cache (something related to gatt caching that is not cleared or closed properly once disconnects). Is there a way to fix this issue of the BLE device or on the mobile device without forgetting the BLE device or clearing cache?

Thanks

[Hung Bui]

Hi Roei, 

I don't think GATT caching would cause a disconnection. Did you change the Attribute table when operating/reflashing ? 

Please try capture a sniffer trace so that we can inspect what happened over the air. 

[Roei]

Hi Hung, thank you for your answer.

Can you please tell me about the operating/reflashing of Attribute table?

Regarding sniffer - I didn't catch any special message before disconnection - just regular messages between the devices.

Thanks!

[Hung Bui]

Hi Roei, 

So when the phone catch the GATT atribute table, it assumes that the peripheral doesn't change the GATT table (services, characteristics) but if when you are developing your application, or if it's the way your application works that it change the service/characteristic structure (the table) then the phone may have an error when trying to use the old table. 
If you can capture a sniffer trace we can actually find if there is anything abnormal, or can explain why the connection only last for few seconds.