rdnt
commented
4 weeks ago Heya folks! I'm marking this as ready-for-review, hoping for an initial review pass. I am not very familiar with BLE, so any feedback, positive or negative, is welcome.
I reckon I saw somewhere (edit: https://github.com/tinygo-org/bluetooth/issues/142#issuecomment-1531906280) that such a change requires implementation for two different platforms. I am not sure if I can commit to implementing this also for e.g. Linux, but if required I will see what I can do. Otherwise this PR can be left open as a working POC until someone contributes a relevant implementation for some other platform.
This PR adds the capability to perform an MTU Exchange procedure from the central (gatt client - usually), and the ability to configure an ATT_MTU up to 247 bytes (allowing 244 bytes of application data).
Configure(cfg Config) errormethod that allows setting some initialization options for the SoftDevice before it is enabled.ExchangeMTU(mtu uint16) (uint16, error)function was added to the Device interface, that can be called from the gatt client to initiate an MTU exchange procedure.I have tested this implementation on two nicenano_v2 boards.
In my tests, I have found updating the event length can allow for increased bandwidth, so I also implemented a way to configure it.
I have made some experiments with adding Data Length Extension as well, but I reckon some initial feedback would be welcome before I delve into starting a proper implementation of DLE.
Do let me know if you would like to have a working example (maybe also in the source code?) with a 247 MTU exchange + throughput test of sorts.
Lastly, I can only test on s140v7, so I can't really verify that the peripheral-only variant (s113v7) works as expected. If someone else could lend a hand I would appreciate that.
Refs:
Relevant: https://github.com/tinygo-org/bluetooth/issues/200#issuecomment-1878675073, https://github.com/tinygo-org/bluetooth/issues/142#issuecomment-1531906280