This is a big rewrite to use DBus calls directly instead of going
through go-bluetooth first.
This is a big change, but I believe it is an improvement. While the
go-bluetooth works for many cases, it's a layer in between that I
believe hurts more than it helps. Without it, we can just program
directly against the BlueZ D-Bus API. The end result is about 10% more
code.
With this rewrite, I fixed the following issues:
* All MapToStruct warnings are gone, like in
https://github.com/tinygo-org/bluetooth/issues/193.
* Advertisements can be restarted after they were stopped. Previously
this resulted in a panic.
* Looking at the source code of go-bluetooth, it appears that it
includes devices from a different Bluetooth adapter than the one
that's currently scanning. This is fixed with the rewrite.
* Fix a bug in Adapter.AddService where it would only allow adding a
single service. Multiple services can now be added.
This was actually the motivating bug that led me down to rewrite the
whole thing because I couldn't figure out where the bug was in
go-bluetooth (it's many layers deep).
* The `WriteEvent` callback in a characteristic now also gets the
'offset' parameter which wasn't provided by go-bluetooth.
This rewrite also avoids go-bluetooth specific workarounds like
https://github.com/tinygo-org/bluetooth/pull/74 and
https://github.com/tinygo-org/bluetooth/pull/121.
I have tested all examples in the smoketest-linux Makefile target. They
all still work with this rewrite.
Remove the Addresser type. It isn't really necessary (the Address type
can change between OSes) and makes it difficult to fix a heap allocation
in interrupts (on the Nordic SoftDevices).
This is a backwards incompatible change, but only programs that use
SetConnectHandler should notice this.
Unlike what I previously thought, BlueZ does expose it. Unfortunately it
doesn't seem to respect it: the bit is not included in D-Bus paths.
Windows also supports the bit, which I hope to fix in a future commit.
Like BlueZ, it appears to ignore it when connecting to a device.
There used to be GAP events (connect/disconnect). The main purpose for
these events was to allow applications to re-start advertisement when a
connection was lost - on nrf. Unfortunately things work differently on
Linux, which already has this behavior and for which I haven't yet
implemented these events. Therefore I have removed these events and
instead added code to automatically restart advertisement on connection
loss.
Supporting multiple (incoming) connections as a peripheral would be
useful, but is not currently supported.
Instead of attempting to allocate multiple advertisement instances, only
use one by default. If needed, a NewAdvertisement method could be added
in the future for devices that actually do support multiple
advertisements at a time.
The motivation for this change is fix an inconsistency with the nrf51
(which already had the behavior of DefaultAdvertisement) and the
discovery that nrf52 devices also don't seem to support more than one
advertisement instance, even though their API does allow for multiple
instances. But the primary motivation is that for consistency with
hosted systems, it would be best if the nrf port would automatically
re-enable advertisement when a connection is lost (or made).
While BlueZ does support more than one instance, it is implemented by
simply iterating through the active advertisement instances so could
also be implemented by doing that manually. I haven't checked the
behavior of Windows and MacOS - but as always, the API is not yet stable
and can be changed if needed.
All initialization can be done in the Enable call. This makes the API a
bit simpler and a bit more consistent between Nordic chips and other BLE
interfaces.
