buzzer: add simple buzzer implementation

Signed-off-by: Ron Evans <ron@hybridgroup.com>

examples/buzzer/main.go

@@ -0,0 +1,40 @@
+package main
+
+import (
+	"machine"
+	"time"
+
+	"tinygo.org/x/drivers/buzzer"
+)
+
+type note struct {
+	tone     float64
+	duration float64
+}
+
+func main() {
+	speaker := machine.PA30
+	speaker.Configure(machine.PinConfig{Mode: machine.PinOutput})
+	speaker.Set(true)
+
+	bzrPin := machine.A0
+	bzrPin.Configure(machine.PinConfig{Mode: machine.PinOutput})
+
+	bzr := buzzer.New(machine.A0)
+
+	song := []note{
+		{buzzer.C4, buzzer.Quarter},
+		{buzzer.D4, buzzer.Quarter},
+		{buzzer.E4, buzzer.Quarter},
+		{buzzer.F4, buzzer.Quarter},
+		{buzzer.G4, buzzer.Quarter},
+		{buzzer.A4, buzzer.Quarter},
+		{buzzer.B4, buzzer.Quarter},
+		{buzzer.C5, buzzer.Quarter},
+	}
+
+	for _, val := range song {
+		bzr.Tone(val.tone, val.duration)
+		time.Sleep(10 * time.Millisecond)
+	}
+}