Bluetooth Low Energy Notification Interval

Question

I have a question regarding the bluetooth LE protocol.

I have an Android Device and a peripheral device.
Looking at the transmission with a sniffer and wireshark there is +/- every 40ms an empty PDU message. As I understood the protocol this means the connection interval those device chose is 40ms.

For testing I am using a simple "UART" application where the android device enables the notification on an antribute of the peripheral device and gets notified whenever the attribute changes.

Now, if I "send" multiple 20 byte packets through this setup, wireshark shows me, that those value notifications are just about 7-10 ms apart. Each Notification contains 20 Bytes

Does that mean, that the connection interval does not apply for notifications and that each notification can hold max. 20 Bytes?

Thanks & Greetings!

Answer 1

There is one connection event per connection interval. In each connection event multiple packets can be sent directly after each other. When no side has anything left to send, the connection event is closed and next exchange will occur at the next connection interval point. So yes, many notifications can be sent in one connection interval.