maximal notification size in s132

RE: maximal notification size in s132

Sigurd — Tue, 13 Jun 2017 13:25:25 GMT

@Boaz I have converted the comment to an answer.

RE: maximal notification size in s132

Boaz — Tue, 13 Jun 2017 13:23:49 GMT

Thanks @Sigurd - can you please post this as an answer so I can accept?

RE: maximal notification size in s132

Sigurd — Tue, 13 Jun 2017 12:18:18 GMT

Hi,

According to the BLE specification the notification length can be max ATT_MTU - 3. The 3 bytes subtracted is the 3-byte header(OP-code (operation, 1 byte) and the attribute handle (2 bytes)).

In BLE 4.1 the ATT_MTU is 23 bytes, but in BLE 4.2 the ATT_MTU can be negotiated up to 247 bytes. Support for Configurable ATT MTU size(longer packets than previously (23 ) was added in S132 version 3.0.0

RE: maximal notification size in s132

endnode — Tue, 13 Jun 2017 11:25:31 GMT

I believe this is not Soft Device limitation but BT SIG specification: Notification can be as long as current maximum ATT_MTU size. That's the difference from Write/Read methods which work on GATT Characteristic's (or Descriptor's) Value handles and can work with whole Value length.