tinygo demo for BBC MicroBit using accelerometer and matrix display

accel_demo.go

package main

import (
	"time"
	"machine"
	"image/color"
	"tinygo.org/x/drivers/microbitmatrix"
	"tinygo.org/x/drivers/mma8653"
)

var i2c mma8653.Device
var display microbitmatrix.Device

func main() {

	// The ic2 bus must already be configured.
	machine.I2C0.Configure(machine.I2CConfig{})

	accel := mma8653.New(machine.I2C0)
	accel.Configure(mma8653.DataRate200Hz, mma8653.Sensitivity2G)

	display = microbitmatrix.New()
	display.Configure(microbitmatrix.Config{})

	display.ClearDisplay()

	x := int16(1)
	y := int16(2)
	c := color.RGBA{255, 255, 255, 255}

	threshold := int32(1000000 / 2)

	then := time.Now()

	for {

		// Must use time and since - delay is blocking.
		if time.Since(then).Nanoseconds() > 80000000  {

			then = time.Now()

			println("hello world!")

			// pointing straight to Earth
			// and the sensor is not moving the returned value will be around 1000000 or
			// -1000000.
			ax, ay, _, _ := accel.ReadAcceleration()

			print("Ax:")
			println(ax)
			print("Ay:")
			println(ay)

			// if we're rotating on the x axis, then inc y.
			if Abs(ax) > threshold {
				if ax > 0 && y < 4 {
					y = y + 1
				} else if ax < 0 && y > 0 {
					y = y - 1
				}
			}
			if Abs(ay) > threshold {
				if ay > 0 && x < 4 {
					x = x + 1
				} else if ay < 0 && x > 0 {
					x = x - 1
				}
			}

			display.ClearDisplay()
			display.SetPixel(x, y, c)
		}
		display.Display()
	}
}

func Abs(x int32) int32 {
	if x < 0 {
		return -x
	}
	return x
}