BLE disconnection - error 133 - on characteristics write

[Roei]

Hi,

I'm using nrf52840 and connecting to a mobile device.

Randomly - I get disconnections with error code 133 - on characteristics write, on mobile side.

In addition - the sniffer doesn't display anything special - besides Encrypted packet decrypted incorrectly (bad MIC), which occurs from the beginning of the connection, and it seems like it's not related to the disconnection.

Can you please help me?

Thanks!

[Simonr]

Hi

GATT Error 133 is a rather infamous issue on Android. This happens more rarely in newer phones, but do sometimes still occur. What phone are you seeing this error in, and what app are you using on that phone? Please try implementing a delay between writes to mitigate these disconnects. If you're using our Android BLE Library, you should be able to add retries instead of causing a disconnection right away.

I think these bad MIC packets you're seeingare caused by the sniffer not having the private keys for the connection, not allowing it to decrypt the packages it picks up. 

Could you upload the sniffer trace so we could take a look?

Best regards,

Simon