BLE examples replicate a UUID for both service and a characteristic

[akauppi]

Bug description

The BLE examples having the same UUID for both service and one characteristic seems like a mistake.

Check these lines:

• esp-hal/examples/src/bin/wifi_ble.rs

  Line 113 in f81b5f6

  uuid: "937312e0-2354-11eb-9f10-fbc30a62cf38",

• esp-hal/examples/src/bin/wifi_embassy_ble.rs

  Line 143 in f81b5f6

  uuid: "937312e0-2354-11eb-9f10-fbc30a62cf38",

        gatt!([service {
            uuid: "937312e0-2354-11eb-9f10-fbc30a62cf38",
            characteristics: [
                characteristic {
                    uuid: "937312e0-2354-11eb-9f10-fbc30a62cf38",
                    read: rf,
                    write: wf,
                },

This works just fine - I don't think the id's of the characteristics vs. their enclosing service really matter - but logically there shouldn't be any connection between the two?

The other characteristics are varied from the same theme, by changing one character. I would suggest to do the same here.

Background about the selection of UUIDs in a StackOverflow answer.

To Reproduce

Observe the links above.

Expected behavior

The BLE samples not only are functional, but also show "intention", i.e. lead the reader in the right direction.

Environment

Does not matter.

[bjoernQ]

We plan to overhaul all the examples including the BLE ones. e.g. something mimicking a real-world device (e.g. a BLE temperature sensor or a HID keyboard)

[akauppi]

Sounds great! I'll keep this ticket open until then, and remove once the new stuff is out. No rush.

[akauppi]

One note on the examples - since the gatt! shows up in the code snippet. Rust Rover IDE has currently a problem with the bleps dependency, because it's not a published package (and features are used). Not your fault, but... since you plan to revise the examples, it's appreciated if outside deps would be ... less ad-hoc, I guess.

end of tangential :)

[lure23]

For comparison, Nordic mentions this "LED Button Service" in their BLE tutorial: https://docs.nordicsemi.com/bundle/ncs-latest/page/nrf/libraries/bluetooth/services/lbs.html#lbs-readme

It has a service UUID and two characteristics, whose UUIDs are derived from that (differ by one char).