Connection params

[aykevl]

Work in progress: I haven't added macOS support yet. done

This is a PR that changes a few things to make Device objects usable in peripheral mode (when another device connects to it):

• It changes *Device to Device. This is a breaking change, but makes things a lot easier to deal with on a SoftDevice (no difficult workarounds needed to avoid allocating a heap object in the interrupt handler).
• It changes SetConnectHandler so that a Device is passed instead of just the address of the connecting device. This is another breaking change, but necessary to support this feature (without ugly hacks). Hopefully this is the last breaking change to SetConnectHandler.
• It now loads the connecting device MAC address, which was previously empty.
• It adds SetConnectionLatency which is necessary for battery operated devices to lower the connection latency and with that lower the current consumption (for example, it lowers the current consumed from 85µA to 10µA according to the online power profiler). This change was my original motivation for this PR.

Discovering services and characteristics was already implemented for central mode, and I've found it works just as well in peripheral mode on the SoftDevice.

Tested:

• This works well on the Circuit Playground Bluefruit.
• This doesn't work correctly on Linux (but it doesn't crash either): it doesn't seem to call the connection handler callback.
• Same for macOS. I don't think it would be very difficult to implement, but preferably it would need advertising support first.
• I haven't tested it on Windows because I don't have easy access to a Windows installation with Bluetooth access. Might try this in my Windows VM though. The smoke test says it compiles.

[aykevl]

This PR is ready for review.

[aykevl]

Rebased after #216 was merged.

This PR is essential to keep the PineTime connected at low power. The default connection latency drains too much power.

[aykevl]

Oops, messed up the rebase. I'll fix this PR soon.

[aykevl]

This should now be fixed. Changes:

• Rebased on the dev branch and fixed the merge conflicts.
• Merged ConnectionLatency struct into ConnectionParams, and renamed SetConnectionLatency to RequestConnectionParams. The reason is that these are connection parameters and in fact all fields (except ConnectionTimeout do have the same meaning in both cases.
• Added stub support for NINA.

[deadprogram]

@aykevl can you please rebase this branch and resolve merge conflict?

[aykevl]

I've fixed the merge conflicts.

[deadprogram]

@Ayke, notifications on the ninafw do not work unless this patch is applied to your PR:

--- a/adapter_ninafw.go
+++ b/adapter_ninafw.go
@@ -21,7 +21,7 @@ type Adapter struct {
 
        connectHandler func(device Device, connected bool)
 
-       connectedDevices     []Device
+       connectedDevices     []*Device
        notificationsStarted bool
 }
 
@@ -33,7 +33,7 @@ var DefaultAdapter = &Adapter{
        connectHandler: func(device Device, connected bool) {
                return
        },
-       connectedDevices: make([]Device, 0, maxConnections),
+       connectedDevices: make([]*Device, 0, maxConnections),
 }
 
 // Enable configures the BLE stack. It must be called before any
@@ -197,7 +197,7 @@ func (a *Adapter) startNotifications() {
        }()
 }
 
-func (a *Adapter) findDevice(handle uint16) Device {
+func (a *Adapter) findDevice(handle uint16) *Device {
        for _, d := range a.connectedDevices {
                if d.handle == handle {
                        if _debug {
@@ -208,5 +208,5 @@ func (a *Adapter) findDevice(handle uint16) Device {
                }
        }
 
-       return Device{}
+       return nil
 }
diff --git a/gap_ninafw.go b/gap_ninafw.go
index 5cf7840..61d743e 100644
--- a/gap_ninafw.go
+++ b/gap_ninafw.go
@@ -176,7 +176,7 @@ func (a *Adapter) Connect(address Address, params ConnectionParams) (Device, err
                                        notificationRegistrations: make([]notificationRegistration, 0),
                                },
                        }
-                       a.connectedDevices = append(a.connectedDevices, d)
+                       a.connectedDevices = append(a.connectedDevices, &d)
 
                        return d, nil
 
@@ -226,7 +226,7 @@ func (d Device) Disconnect() error {
                return err
        }
 
-       d.adapter.connectedDevices = []Device{}
+       d.adapter.connectedDevices = []*Device{}
        return nil
 }

[aykevl]

@Ayke, notifications on the ninafw do not work unless this patch is applied to your PR:

Huh that's odd.
How did you test this? I'd like to try to reproduce this.

[deadprogram]

OK just tried again and now I cannot repro this myself. I tried on both nano-rp2040 and pyportal, and it worked as expected.

Maybe my local config was messed up at the time? Sounds like time to merge. Thanks for working on this @aykevl

[aykevl]

Thank you! 🎉