examples: add example code for BlinkM

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

examples/blinkm/main.go

@@ -0,0 +1,41 @@
+// Connects to an BlinkM I2C RGB LED.
+// http://thingm.com/fileadmin/thingm/downloads/BlinkM_datasheet.pdf
+package main
+
+import (
+	"machine"
+	"time"
+
+	"github.com/tinygo-org/drivers/blinkm"
+)
+
+func main() {
+	machine.I2C0.Configure(machine.I2CConfig{})
+
+	bm := blinkm.New(machine.I2C0)
+	bm.Configure()
+
+	maj, min, _ := bm.Version()
+
+	println("Firmware version:", string(maj), string(min))
+
+	count := 0
+	for {
+		switch count {
+		case 0:
+			// Crimson
+			bm.SetRGB(0xdc, 0x14, 0x3c)
+			count = 1
+		case 1:
+			// MediumPurple
+			bm.SetRGB(0x93, 0x70, 0xdb)
+			count = 2
+		case 2:
+			// MediumSeaGreen
+			bm.SetRGB(0x3c, 0xb3, 0x71)
+			count = 0
+		}
+
+		time.Sleep(100 * time.Millisecond)
+	}
+}