gap: implement basic event handling: connect/disconnect

adapter.go

@@ -0,0 +1,12 @@
+package bluetooth
+
+// SetEventHandler sets the callback that gets called on incoming events.
+//
+// Warning: must only be called when the Bluetooth stack has not yet been
+// initialized!
+func (a *Adapter) SetEventHandler(handler func(Event)) {
+	a.handler = handler
+}
+
+// Event is a global Bluetooth stack event.
+type Event interface{}

adapter_sd.go

@@ -18,9 +18,14 @@ import "C"
 import (
 	"device/arm"
 	"device/nrf"
+	"errors"
 	"unsafe"
 )
 
+var (
+	ErrNotDefaultAdapter = errors.New("bluetooth: not the default adapter")
+)
+
 //export assertHandler
 func assertHandler() {
 	println("SoftDevice assert")
@@ -52,15 +57,21 @@ func init() {
 // Adapter is a dummy adapter: it represents the connection to the (only)
 // SoftDevice on the chip.
 type Adapter struct {
+	isDefault bool
+	handler   func(Event)
 }
 
 // DefaultAdapter is an adapter to the default Bluetooth stack on a given
 // target.
-var DefaultAdapter = &Adapter{}
+var DefaultAdapter = &Adapter{isDefault: true}
 
 // Enable configures the BLE stack. It must be called before any
 // Bluetooth-related calls (unless otherwise indicated).
 func (a *Adapter) Enable() error {
+	if !a.isDefault {
+		return ErrNotDefaultAdapter
+	}
+
 	// Enable the IRQ that handles all events.
 	arm.EnableIRQ(nrf.IRQ_SWI2)
 	arm.SetPriority(nrf.IRQ_SWI2, 192)
@@ -96,7 +107,23 @@ func (a *Adapter) Enable() error {
 }
 
 func handleEvent() {
-	// TODO: do something with the events.
+	handler := DefaultAdapter.handler
+	if handler == nil {
+		return
+	}
+	id := eventBuf.header.evt_id
+	switch {
+	case id >= C.BLE_GAP_EVT_BASE && id <= C.BLE_GAP_EVT_LAST:
+		gapEvent := GAPEvent{
+			Connection: Connection(eventBuf.evt.unionfield_gap_evt().conn_handle),
+		}
+		switch id {
+		case C.BLE_GAP_EVT_CONNECTED:
+			handler(&ConnectEvent{GAPEvent: gapEvent})
+		case C.BLE_GAP_EVT_DISCONNECTED:
+			handler(&DisconnectEvent{GAPEvent: gapEvent})
+		}
+	}
 }
 
 //go:export SWI2_EGU2_IRQHandler

examples/heartrate/main.go

@@ -12,6 +12,7 @@ var advPayload = []byte("\x02\x01\x06" + "\x07\x09TinyGo")
 func main() {
 	println("starting")
 	adapter := bluetooth.DefaultAdapter
+	adapter.SetEventHandler(handleBluetoothEvents)
 	must("enable SD", adapter.Enable())
 	adv := adapter.NewAdvertisement()
 	options := &bluetooth.AdvertiseOptions{
@@ -45,3 +46,15 @@ func must(action string, err error) {
 		panic("failed to " + action + ": " + err.Error())
 	}
 }
+
+// handleBluetoothEvents prints BLE events as they happen.
+func handleBluetoothEvents(evt bluetooth.Event) {
+	switch evt := evt.(type) {
+	case *bluetooth.ConnectEvent:
+		println("evt: connected", evt.Connection)
+	case *bluetooth.DisconnectEvent:
+		println("evt: disconnected", evt.Connection)
+	default:
+		println("evt: unknown")
+	}
+}

gap.go

@@ -19,3 +19,21 @@ func NewAdvertiseInterval(intervalMillis uint32) AdvertiseInterval {
 	// Convert an interval to units of
 	return AdvertiseInterval(intervalMillis * 8 / 5)
 }
+
+// Connection is a numeric identifier that indicates a connection handle.
+type Connection uint16
+
+// GAPEvent is a base (embeddable) event for all GAP events.
+type GAPEvent struct {
+	Connection Connection
+}
+
+// ConnectEvent occurs when a remote device connects to this device.
+type ConnectEvent struct {
+	GAPEvent
+}
+
+// DisconnectEvent occurs when a remote device disconnects from this device.
+type DisconnectEvent struct {
+	GAPEvent
+}