Whats the recommended way to differentiate Characteristic handles? #82
Comments
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Good question... I think one way could be to have the CharacteristiBuilder::build() return Characteristic rather than AttributeHandle, and if we add PartialEq on Characteristic it should be possible to check and match? That way you can't construct handles that are not provided by trouble. |
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yeah that seems like a good idea. A match on handles would be great. Regarding "That way you can't construct handles that are not provided by trouble." I am not sure if i understand correctly what you mean by that. Is there a usecase for handles which are not handled by trouble? |
No I don't think there are any such use case. I was just thinking out louad that if it exposed the u16 and you could compare that, you'd not be able to guarantee that you always compared with a valid handle, so a good thing. |
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Thank you very much for implementing a fix that fast! Sadly i still have problems as it seems the equal check does not work correctly. It always enters the first one no matter the characteristic I actually write to. But the handle id is indeed different so maybe comparing on this number would be an option? Although I am still a little be confused what that number actually represents and why it's incrementing that often. ...
let mut bat_level = [23; 1];
let battery_lvl_handle = {
let mut svc = table.add_service(Service::new(0x1800));
let _ = svc.add_characteristic_ro(0x2a00, id);
let _ = svc.add_characteristic_ro(0x2a01, &appearance[..]);
svc.build();
// Generic attribute service (mandatory)
table.add_service(Service::new(0x1801));
// Battery service
let mut svc = table.add_service(Service::new(0x180f));
svc.add_characteristic(
0x2a19,
&[CharacteristicProp::Read, CharacteristicProp::Notify],
&mut bat_level,
)
.build()
};
// Event Service for all events that happened on device
let mut event_buffer = [0u8; 40]; // Adjust size as needed
let events_handle = {
let mut svc = table.add_service(Service::new(EVENT_SERVICE_UUID));
svc.add_characteristic(
EVENT_CHARACTERISTIC_UUID,
&[
CharacteristicProp::Read,
CharacteristicProp::Write,
CharacteristicProp::Notify,
],
&mut event_buffer,
)
.build()
};
info!("Starting advertising and GATT service");
let _ = join3(
ble.run(),
async {
loop {
match server.next().await {
Ok(GattEvent::Write {
handle,
connection: _,
}) => {
info!("HANDLE Info {:?}", handle);
if handle == battery_lvl_handle {
// always enters here although its not the correct handle
info!("is battery_lvl_handle");
} else if handle == events_handle {
info!("is events_handle");
}
}
.... |
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@lulf sadly cannot reopen issue myself :) |
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@Syphixs I think this fixes the issue #88. It also adds a test case to check that handle in event matches what was created by table. The handles would not match earlier because the event handle didn't contain the cccd field. It doesn't explain the fact that you do match on the battery_lvl_handle though, I found that strange. |
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Could you try again with latest main? |
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Yeah now it works great! Thank you! :) maybe it had something to do with a strange warning I also got which was: but now this also went away. I will keep an eye out for further strange behavior. Thanks again! Will close it as the issue is fixed. |
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Ah yes, that unsupported thing is iPhone specific. Basically iOS is probing using an illegal l2cap channel id, maybe for some Apple specific feature. Should probably make that less error-y |
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@lulf I got the same my trace: |
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Are you sure they are related? All iOS devices probes that l2cap channel id, but it should not cause a disconnect, at least that does not happen for me (nor for production firmware running trouble). Are you using one of the example applications? |
ah I'm running my own code using trouble, not the example. I got |
Lets assume I have two or more Characteristics and want do differentiate between them on an write event easily. Whats the recommended way of doing this as the 'handle' field of 'Characteristic' is private to outside the crate? Do i need to build an outside table to link the handle number back to my characteristics?
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