examples: add basic usage example for mma8653

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

examples/mma8653/main.go

@@ -0,0 +1,22 @@
+// Connects to an MMA8653 I2C accelerometer.
+package main
+
+import (
+	"machine"
+	"time"
+
+	"github.com/tinygo-org/drivers/mma8653"
+)
+
+func main() {
+	machine.I2C0.Configure(machine.I2CConfig{})
+
+	accel := mma8653.New(machine.I2C0)
+	accel.Configure(mma8653.DataRate200Hz)
+
+	for {
+		x, y, z := accel.ReadAcceleration()
+		println(x, y, z)
+		time.Sleep(time.Millisecond * 100)
+	}
+}