makeybutton: revise to better match the algorithm defined by the original

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

examples/makeybutton/main.go

@@ -9,7 +9,7 @@ import (
 
 var (
 	led    machine.Pin = machine.LED
-	button machine.Pin = machine.BUTTON
+	button machine.Pin = machine.D10
 	key    *makeybutton.Button
 )
 
@@ -25,6 +25,7 @@ func main() {
 		case makeybutton.Released:
 			led.Low()
 		}
-		time.Sleep(100 * time.Millisecond)
+		// the more frequent the more responsive
+		time.Sleep(50 * time.Millisecond)
 	}
 }

makeybutton/buffer.go

@@ -1,11 +1,17 @@
 package makeybutton
 
-const bufferSize = 6
+const (
+	bufferSize    = 3
+	maxSumAllowed = 4
+)
 
 // Buffer is a buffer to keep track of the most recent readings for a button.
+// in bit form.
 type Buffer struct {
-	readings [bufferSize]bool
-	index    int
+	data        [bufferSize]byte
+	byteCounter int
+	bitCounter  int
+	sum         int
 }
 
 // NewBuffer returns a new buffer.
@@ -13,34 +19,47 @@ func NewBuffer() *Buffer {
 	return &Buffer{}
 }
 
-// Used returns how many bytes in buffer have been used.
-func (b *Buffer) Used() int {
-	return b.index
+// Sum returns the sum of all measurements
+func (b *Buffer) Sum() int {
+	return b.sum
 }
 
-// Put stores a boolean in the buffer.
-func (b *Buffer) Put(val bool) bool {
-	b.index++
-	if b.index >= bufferSize {
-		b.index = 0
+// Put stores a boolean button state into the buffer.
+func (b *Buffer) Put(val bool) {
+	currentMeasurement, oldestMeasurement := b.updateData(val)
+	b.updateCounters()
+
+	if currentMeasurement != 0 && b.sum < maxSumAllowed {
+		b.sum++
 	}
 
-	b.readings[b.index] = val
-
-	return true
+	if oldestMeasurement != 0 && b.sum > 0 {
+		b.sum--
+	}
 }
 
-// Avg returns the "average" of all the readings in the buffer, by
-// treating a true as 1 and a false as -1.
-func (b *Buffer) Avg() int {
-	avg := 0
-	for i := 0; i < bufferSize; i++ {
-		if b.readings[i] {
-			avg += 1
-		} else {
-			avg -= 1
+func (b *Buffer) updateData(val bool) (byte, byte) {
+	currentByte := b.data[b.byteCounter]
+	oldestMeasurement := (currentByte >> b.bitCounter) & 0x01
+
+	if val {
+		currentByte |= (1 << b.bitCounter)
+	} else {
+		currentByte &= ^(1 << b.bitCounter)
+	}
+
+	b.data[b.byteCounter] = currentByte
+
+	return (currentByte >> b.bitCounter) & 0x01, oldestMeasurement
+}
+
+func (b *Buffer) updateCounters() {
+	b.bitCounter++
+	if b.bitCounter == 8 {
+		b.bitCounter = 0
+		b.byteCounter++
+		if b.byteCounter == bufferSize {
+			b.byteCounter = 0
 		}
 	}
-
-	return avg
 }

makeybutton/button.go

@@ -4,6 +4,8 @@
 // Inspired by the amazing MakeyMakey
 // https://makeymakey.com/
 //
+// This code is a reinterpretation of
+// https://github.com/sparkfun/MaKeyMaKey/blob/master/firmware/Arduino/makey_makey/makey_makey.ino
 package makeybutton
 
 import (
@@ -11,6 +13,11 @@ import (
 	"time"
 )
 
+var (
+	pressThreshold   int = 1
+	releaseThreshold int = 0
+)
+
 // ButtonState represents the state of a MakeyButton.
 type ButtonState int
 
@@ -33,6 +40,7 @@ const (
 type Button struct {
 	pin              machine.Pin
 	state            ButtonState
+	pressed          bool
 	readings         *Buffer
 	HighMeansPressed bool
 }
@@ -49,7 +57,7 @@ func NewButton(pin machine.Pin) *Button {
 
 // Configure configures the Makey Button pin to have the correct settings to detect touches.
 func (b *Button) Configure() error {
-	// Note that we have to first turn on the pullup, and then turn off the pullup,
+	// Note that on AVR we have to first turn on the pullup, and then turn off the pullup,
 	// in order for the pin to be properly floating.
 	b.pin.Configure(machine.PinConfig{Mode: machine.PinInputPullup})
 	time.Sleep(10 * time.Millisecond)
@@ -62,30 +70,36 @@ func (b *Button) Configure() error {
 // Get returns a ButtonEvent based on the most recent state of the button,
 // and if it has changed by being pressed or released.
 func (b *Button) Get() ButtonEvent {
-	// if pin is pulled up, a low value means the key is pressed
-	pressed := !b.pin.Get()
-	if b.HighMeansPressed {
-		// otherwise, a high value means the key is pressed
-		pressed = !pressed
-	}
+	b.update()
 
-	avg := b.readings.Avg()
-	b.readings.Put(pressed)
-
-	switch {
-	case pressed && avg > -1*bufferSize+2:
-		if b.state == Press {
-			return NotChanged
-		}
-
-		b.state = Press
-		return Pressed
-	case !pressed:
-		if b.state == Press {
+	if b.pressed {
+		// the button had previously been pressed,
+		// but now appears to have been released.
+		if b.readings.Sum() <= releaseThreshold {
+			b.pressed = false
 			b.state = Release
 			return Released
 		}
+	} else {
+		// the button had previously not been pressed,
+		// but now appears to have been pressed.
+		if b.readings.Sum() >= pressThreshold {
+			b.pressed = true
+			b.state = Press
+			return Pressed
+		}
 	}
 
 	return NotChanged
 }
+
+func (b *Button) update() {
+	// if pin is pulled up, a low value means the key is pressed
+	press := !b.pin.Get()
+	if b.HighMeansPressed {
+		// otherwise, a high value means the key is pressed
+		press = !press
+	}
+
+	b.readings.Put(press)
+}