lis3dh: implement accelerometer functionality

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

examples/lis3dh/main.go

@@ -0,0 +1,32 @@
+// Connects to a LIS3DH I2C accelerometer on the Adafruit Circuit Playground Express.
+package main
+
+import (
+	"machine"
+	"time"
+
+	"github.com/tinygo-org/drivers/lis3dh"
+)
+
+var i2c = machine.I2C1
+
+func main() {
+	i2c.Configure(machine.I2CConfig{})
+
+	accel := lis3dh.New(i2c)
+	accel.Address = lis3dh.Address1 // address on the Circuit Playground Express
+	accel.Configure()
+	accel.SetRange(lis3dh.RANGE_2_G)
+
+	println(accel.Connected())
+
+	for {
+		x, y, z, _ := accel.ReadAcceleration()
+		println("X:", x, "Y:", y, "Z:", z)
+
+		rx, ry, rz := accel.ReadRawAcceleration()
+		println("X (raw):", rx, "Y (raw):", ry, "Z (raw):", rz)
+
+		time.Sleep(time.Millisecond * 100)
+	}
+}