board/board-pybadge.go

//go:build pybadge

package board

import (
	"machine"
	"math/bits"
	"time"

	"tinygo.org/x/drivers"
	"tinygo.org/x/drivers/lis3dh"
	"tinygo.org/x/drivers/pixel"
	"tinygo.org/x/drivers/shifter"
	"tinygo.org/x/drivers/st7735"
	"tinygo.org/x/drivers/ws2812"
)

const (
	Name = "pybadge"
)

var (
	Power   = mainBattery{}
	Sensors = &allSensors{}
	Display = mainDisplay{}
	Buttons = &buttonsConfig{}
)

func init() {
	AddressableLEDs = &ws2812LEDs{}
}

type mainBattery struct {
}

func (b mainBattery) Configure() {
	machine.InitADC()
	machine.ADC{Pin: machine.A6}.Configure(machine.ADCConfig{
		Samples: 4, // 4 seems to be good enough
	})
}

func (b mainBattery) Status() (ChargeState, uint32, int8) {
	rawValue := machine.ADC{Pin: machine.A6}.Get()
	// Formula to calculate microvolts:
	//   rawValue * 6600_000 / 0x10000
	// Simlified, to fit in 32-bit integers:
	//   rawValue * 51562 / 512
	microvolts := uint32(rawValue) * 51562 / 512
	return UnknownBattery, microvolts, lithumBatteryApproximation.approximate(microvolts)
}

type allSensors struct {
	baseSensors
	accelX, accelY, accelZ int32
}

var accel lis3dh.Device

func (s *allSensors) Configure(which drivers.Measurement) error {
	if which&drivers.Acceleration != 0 {
		machine.I2C0.Configure(machine.I2CConfig{
			Frequency: 400 * machine.KHz,
			SCL:       machine.SCL_PIN,
			SDA:       machine.SDA_PIN,
		})
		accel = lis3dh.New(machine.I2C0)
		accel.Configure()
	}
	return nil
}

func (s *allSensors) Update(which drivers.Measurement) error {
	// TODO:
	// - read temperature from LIS3DH
	// - read brightness value
	if which&drivers.Acceleration != 0 {
		var err error
		s.accelX, s.accelY, s.accelZ, err = accel.ReadAcceleration()
		if err != nil {
			return err
		}
	}
	return nil
}

func (s *allSensors) Acceleration() (x, y, z int32) {
	// Adjust accelerometer to match standard axes.
	x = -s.accelX
	y = s.accelY
	z = -s.accelZ
	return
}

type mainDisplay struct{}

func (d mainDisplay) PPI() int {
	return 116 // 160px / (35.04mm / 25.4)
}

func (d mainDisplay) Configure() Displayer[pixel.RGB565BE] {
	machine.SPI1.Configure(machine.SPIConfig{
		SCK:       machine.SPI1_SCK_PIN,
		SDO:       machine.SPI1_SDO_PIN,
		SDI:       machine.SPI1_SDI_PIN,
		Frequency: 15_000_000, // datasheet for st7735 says 66ns (~15.15MHz) is the max speed
	})

	display := st7735.New(machine.SPI1, machine.TFT_RST, machine.TFT_DC, machine.TFT_CS, machine.TFT_LITE)
	display.Configure(st7735.Config{
		Rotation: st7735.ROTATION_90,
	})
	display.EnableBacklight(false)
	return &display
}

func (d mainDisplay) MaxBrightness() int {
	return 1
}

func (d mainDisplay) SetBrightness(level int) {
	machine.TFT_LITE.Set(level > 0)
}

func (d mainDisplay) WaitForVBlank(defaultInterval time.Duration) {
	dummyWaitForVBlank(defaultInterval)
}

func (d mainDisplay) ConfigureTouch() TouchInput {
	return noTouch{}
}

type buttonsConfig struct {
	shifter.Device
	lastState, currentState uint8
}

func (b *buttonsConfig) Configure() {
	b.Device = shifter.NewButtons()
	b.Device.Configure()
}

func (b *buttonsConfig) ReadInput() {
	b.currentState, _ = b.Device.ReadInput()
}

var codes = [8]Key{
	KeyLeft,
	KeyUp,
	KeyDown,
	KeyRight,
	KeySelect,
	KeyStart,
	KeyA,
	KeyB,
}

func (b *buttonsConfig) NextEvent() KeyEvent {
	// The xor between the previous state and the current state is the buttons
	// that changed.
	change := b.currentState ^ b.lastState
	if change == 0 {
		return NoKeyEvent
	}

	// Find the index of the button with the lowest index that changed state.
	index := bits.TrailingZeros32(uint32(change))
	e := KeyEvent(codes[index])
	if b.currentState&(1<<index) == 0 {
		// The button state change was from 1 to 0, so it was released.
		e |= keyReleased
	}

	// This button event was read, so mark it as such.
	// By toggling the bit, the bit will be set to the value that is currently
	// in currentState.
	b.lastState ^= (1 << index)

	return e
}

type ws2812LEDs struct {
	data [5]colorGRB
}

func (l *ws2812LEDs) Configure() {
	machine.WS2812.Configure(machine.PinConfig{Mode: machine.PinOutput})
}

func (l *ws2812LEDs) Len() int {
	return len(l.data)
}

func (l *ws2812LEDs) SetRGB(i int, r, g, b uint8) {
	l.data[i] = colorGRB{
		R: r,
		G: g,
		B: b,
	}
}

// Send pixel data to the LEDs.
func (l *ws2812LEDs) Update() {
	ws := ws2812.Device{Pin: machine.WS2812}
	ws.Write(pixelsToBytes(l.data[:]))
}