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adafruit / Adafruit_Blinka_bleio

`_bleio` for Blinka based on `bleak`
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Fix properties check to use Bleak Write value #40

Open philrittenhouse opened 3 years ago

philrittenhouse commented 3 years ago

Re: Issue #39 Unable to Write Characteristic

I have tested this change on Windows 10

Let me know if there is anything I missed.

Thanks, Phil

dhalbert commented 3 years ago

After looking at this in more detail, I think the problem may be instead that this code is wrong: https://github.com/adafruit/Adafruit_Blinka_bleio/blob/a7d037244956a2d77e99250f76c11f9660d46386/_bleio/common.py#L531-L532 It is assuming that the bleak property bits are the same as the ones I defined. Instead, we need a mapping from each bleak bit to each other bit, or we need to change our bits to match bleak's. The bits chosen here were the same ones that nRF uses, so I think it might be better to do the mapping, rather than just change the bit values. But I need to think about that. I Your change works for that particular bit, but it might not work for the others. I will look at this again tomorrow; it's late at the moment. I'm sorry I led you astray in your initial proposed change.

philrittenhouse commented 3 years ago

I have been doing some digging and I have found a few sources that seem to suggest the characterstic properties are defined in the spec. I don't have access to the spec to confirm but this table from Nordic suggests the values are defined in the BLE Core Spec v4.2

https://devzone.nordicsemi.com/nordic/short-range-guides/b/bluetooth-low-energy/posts/ble-characteristics-a-beginners-tutorial image

ukBaz commented 3 years ago

The Core Specification is open to anyone and is available at:

https://www.bluetooth.com/specifications/specs/core-specification/

The version has moved on to 5.3 now but this data shouldn't be changing.

I think this is the table you are referring to:

image

markjbianchi commented 6 months ago

I came across this same issue (and just now found this pull request), and traced it down to the Characteristic.READ/WRITE/etc bit masks not matching the BLE standard, as shown above. I think the correct fix would be to simply change the property bit mask values in Characteristic class in common.py to match that standard. I have done that locally and it works perfectly now.