makeybutton: add driver for MakeyMakey-like button

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

Makefile

@@ -239,13 +239,15 @@ endif
 	@md5sum ./build/test.hex
 	tinygo build -size short -o ./build/test.uf2 -target=pico ./examples/scd4x/main.go
 	@md5sum ./build/test.uf2
+	tinygo build -size short -o ./build/test.uf2 -target=circuitplay-express ./examples/makeybutton/main.go
+	@md5sum ./build/test.uf2
 
 DRIVERS = $(wildcard */)
 NOTESTS = build examples flash semihosting pcd8544 shiftregister st7789 microphone mcp3008 gps microbitmatrix \
 		hcsr04 ssd1331 ws2812 thermistor apa102 easystepper ssd1351 ili9341 wifinina shifter hub75 \
 		hd44780 buzzer ssd1306 espat l9110x st7735 bmi160 l293x keypad4x4 max72xx p1am tone tm1637 \
 		pcf8563 mcp2515 servo sdcard rtl8720dn image cmd i2csoft hts221 lps22hb apds9960 axp192 xpt2046 \
-		ft6336 sx126x ssd1289 irremote uc8151
+		ft6336 sx126x ssd1289 irremote uc8151 makeybutton
 TESTS = $(filter-out $(addsuffix /%,$(NOTESTS)),$(DRIVERS))
 
 unit-test:

README.md

@@ -52,7 +52,7 @@ func main() {
 
 ## Currently supported devices
 
-The following 80 devices are supported.
+The following 81 devices are supported.
 
 | Device Name                                                                                                                                                                                         | Interface Type |
 |-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-------------|
@@ -100,6 +100,7 @@ The following 80 devices are supported.
 | [LSM6DS3TR accelerometer](https://www.st.com/resource/en/datasheet/lsm6ds3tr.pdf)                                                                                                                     | I2C |
 | [LSM303AGR accelerometer](https://www.st.com/resource/en/datasheet/lsm303agr.pdf)                                                                                                                   | I2C |
 | [LSM9DS1 accelerometer](https://www.st.com/resource/en/datasheet/lsm9ds1.pdf)                                                                                                                       | I2C |
+| [Makey Button](https://makeymakey.com/)                                                                                                                   | GPIO |
 | [MAG3110 magnetometer](https://www.nxp.com/docs/en/data-sheet/MAG3110.pdf)                                                                                                                          | I2C |
 | [MAX7219 & MAX7221 display driver](https://datasheets.maximintegrated.com/en/ds/MAX7219-MAX7221.pdf)                                                                                                | SPI |
 | [MCP2515 Stand-Alone CAN Controller with SPI Interface](https://ww1.microchip.com/downloads/en/DeviceDoc/MCP2515-Family-Data-Sheet-DS20001801K.pdf)                                                 | SPI |

examples/makeybutton/main.go

@@ -0,0 +1,30 @@
+package main
+
+import (
+	"machine"
+	"time"
+
+	"tinygo.org/x/drivers/makeybutton"
+)
+
+var (
+	led    machine.Pin = machine.LED
+	button machine.Pin = machine.BUTTON
+	key    *makeybutton.Button
+)
+
+func main() {
+	led.Configure(machine.PinConfig{Mode: machine.PinOutput})
+	button.Configure(machine.PinConfig{Mode: machine.PinInputPullup})
+	key = makeybutton.NewButton(button)
+
+	for {
+		switch key.Get() {
+		case makeybutton.Pressed:
+			led.High()
+		case makeybutton.Released:
+			led.Low()
+		}
+		time.Sleep(30 * time.Millisecond)
+	}
+}

makeybutton/buffer.go

@@ -0,0 +1,46 @@
+package makeybutton
+
+const bufferSize = 10
+
+// Buffer is a buffer to keep track of the most recent readings for a button.
+type Buffer struct {
+	readings [bufferSize]bool
+	index    int
+}
+
+// NewBuffer returns a new buffer.
+func NewBuffer() *Buffer {
+	return &Buffer{}
+}
+
+// Used returns how many bytes in buffer have been used.
+func (b *Buffer) Used() int {
+	return b.index
+}
+
+// Put stores a boolean in the buffer.
+func (b *Buffer) Put(val bool) bool {
+	b.index++
+	if b.index >= bufferSize {
+		b.index = 0
+	}
+
+	b.readings[b.index] = val
+
+	return true
+}
+
+// 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
+		}
+	}
+
+	return avg
+}

makeybutton/button.go

@@ -0,0 +1,79 @@
+// Package makeybutton providers a driver for a button that can be triggered
+// by anything that is conductive by using an ultra high value resistor.
+//
+// Inspired by the amazing MakeyMakey
+// https://makeymakey.com/
+//
+package makeybutton
+
+import "machine"
+
+// ButtonState represents the state of a MakeyButton.
+type ButtonState int
+
+const (
+	NeverPressed ButtonState = 0
+	Press                    = 1
+	Release                  = 2
+)
+
+// ButtonEvent represents when the state of a Button changes.
+type ButtonEvent int
+
+const (
+	NotChanged ButtonEvent = 0
+	Pressed                = 1
+	Released               = 2
+)
+
+// Button is a "button"-like device that acts like a MakeyMakey.
+type Button struct {
+	pin              machine.Pin
+	state            ButtonState
+	readings         *Buffer
+	HighMeansPressed bool
+}
+
+// NewButton creates a new Button.
+func NewButton(pin machine.Pin) *Button {
+	pin.Configure(machine.PinConfig{Mode: machine.PinInput})
+	pin.Set(false)
+
+	return &Button{
+		pin:              pin,
+		state:            NeverPressed,
+		readings:         NewBuffer(),
+		HighMeansPressed: false,
+	}
+}
+
+// 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
+	}
+
+	avg := b.readings.Avg()
+	b.readings.Put(pressed)
+
+	switch {
+	case pressed && avg > 0:
+		if b.state == Press {
+			return NotChanged
+		}
+
+		b.state = Press
+		return Pressed
+	case !pressed:
+		if b.state == Press {
+			b.state = Release
+			return Released
+		}
+	}
+
+	return NotChanged
+}