added generic 8bit shift register (#107)

* shifter: added generic 8bit shift register driver with ShiftPin Pin-compatible GPIO interface

Makefile

@@ -65,6 +65,8 @@ smoke-test:
 	@md5sum ./build/test.hex
 	tinygo build -size short -o ./build/test.hex -target=microbit ./examples/pcd8544/setpixel/main.go
 	@md5sum ./build/test.hex
+	tinygo build -size short -o ./build/test.hex -target=pybadge ./examples/shifter/main.go
+	@md5sum ./build/test.hex
 	tinygo build -size short -o ./build/test.hex -target=microbit ./examples/sht3x/main.go
 	@md5sum ./build/test.hex
 	tinygo build -size short -o ./build/test.hex -target=microbit ./examples/ssd1306/i2c_128x32/main.go

README.md

@@ -80,6 +80,7 @@ The following 34 devices are supported.
 | [MMA8653 accelerometer](https://www.nxp.com/docs/en/data-sheet/MMA8653FC.pdf) | I2C |
 | [MPU6050 accelerometer/gyroscope](https://store.invensense.com/datasheets/invensense/MPU-6050_DataSheet_V3%204.pdf) | I2C |
 | [PCD8544 display](http://eia.udg.edu/~forest/PCD8544_1.pdf) | SPI |
+| [Shift register](https://en.wikipedia.org/wiki/Shift_register#Parallel-in_serial-out_\(PISO\)) | GPIO |
 | [SHT3x Digital Humidity Sensor](https://www.sensirion.com/fileadmin/user_upload/customers/sensirion/Dokumente/0_Datasheets/Humidity/Sensirion_Humidity_Sensors_SHT3x_Datasheet_digital.pdf) | I2C |
 | [SSD1306 OLED display](https://cdn-shop.adafruit.com/datasheets/SSD1306.pdf) | I2C / SPI |
 | [SSD1331 TFT color display](https://www.crystalfontz.com/controllers/SolomonSystech/SSD1331/381/) | SPI |

examples/shifter/main.go

@@ -0,0 +1,50 @@
+package main
+
+import (
+	"machine"
+	"time"
+
+	"tinygo.org/x/drivers/shifter"
+)
+
+func main() {
+	buttons := shifter.New(shifter.EIGHT_BITS, machine.BUTTON_LATCH, machine.BUTTON_CLK, machine.BUTTON_OUT)
+	buttons.Configure()
+
+	for {
+		// Slower
+		for i := 0; i < 8; i++ {
+			if buttons.Pins[i].Get() {
+				println("Button", i, "pressed")
+			}
+		}
+
+		// Faster
+		pressed, _ := buttons.Read8Input()
+		if pressed&machine.BUTTON_LEFT_MASK > 0 {
+			println("Button LEFT pressed")
+		}
+		if pressed&machine.BUTTON_UP_MASK > 0 {
+			println("Button UP pressed")
+		}
+		if pressed&machine.BUTTON_DOWN_MASK > 0 {
+			println("Button DOWN pressed")
+		}
+		if pressed&machine.BUTTON_RIGHT_MASK > 0 {
+			println("Button RIGHT pressed")
+		}
+		if pressed&machine.BUTTON_SELECT_MASK > 0 {
+			println("Button SELECT pressed")
+		}
+		if pressed&machine.BUTTON_START_MASK > 0 {
+			println("Button START pressed")
+		}
+		if pressed&machine.BUTTON_A_MASK > 0 {
+			println("Button A pressed")
+		}
+		if pressed&machine.BUTTON_B_MASK > 0 {
+			println("Button B pressed")
+		}
+		time.Sleep(100 * time.Millisecond)
+	}
+}

shifter/shifter.go

@@ -0,0 +1,104 @@
+// Package shifter is for 8bit shift register, most common are 74HC165 and 74165
+package shifter // import "tinygo.org/x/drivers/shifter"
+
+import (
+	"errors"
+	"machine"
+)
+
+const (
+	EIGHT_BITS     NumberBit = 8
+	SIXTEEN_BITS   NumberBit = 16
+	THIRTYTWO_BITS NumberBit = 32
+)
+
+type NumberBit int8
+
+// Device holds the Pins.
+type Device struct {
+	latch machine.Pin
+	clk   machine.Pin
+	out   machine.Pin
+	Pins  []ShiftPin
+	bits  NumberBit
+}
+
+// ShiftPin is the implementation of the ShiftPin interface.
+type ShiftPin struct {
+	pin machine.Pin
+	d   *Device
+}
+
+// New returns a new thermistor driver given an ADC pin.
+func New(numBits NumberBit, latch, clk, out machine.Pin) Device {
+	return Device{
+		latch: latch,
+		clk:   clk,
+		out:   out,
+		Pins:  make([]ShiftPin, int(numBits)),
+		bits:  numBits,
+	}
+}
+
+// Configure here just for interface compatibility.
+func (d *Device) Configure() {
+	d.latch.Configure(machine.PinConfig{Mode: machine.PinOutput})
+	d.clk.Configure(machine.PinConfig{Mode: machine.PinOutput})
+	d.out.Configure(machine.PinConfig{Mode: machine.PinInput})
+	for i := 0; i < int(d.bits); i++ {
+		d.Pins[i] = d.GetShiftPin(i)
+	}
+}
+
+// GetShiftPin returns an ShiftPin for a specific input.
+func (d *Device) GetShiftPin(input int) ShiftPin {
+	return ShiftPin{pin: machine.Pin(input), d: d}
+}
+
+// Read8Input reads the 8 inputs and return an uint8
+func (d *Device) Read8Input() (uint8, error) {
+	if d.bits != EIGHT_BITS {
+		return 0, errors.New("wrong amount of registers")
+	}
+	return uint8(d.readInput(EIGHT_BITS)), nil
+}
+
+// Read16Input reads the 16 inputs and return an uint16
+func (d *Device) Read16Input() (uint16, error) {
+	if d.bits != SIXTEEN_BITS {
+		return 0, errors.New("wrong amount of registers")
+	}
+	return uint16(d.readInput(SIXTEEN_BITS)), nil
+}
+
+// Read32Input reads the 32 inputs and return an uint32
+func (d *Device) Read32Input() (uint32, error) {
+	if d.bits != THIRTYTWO_BITS {
+		return 0, errors.New("wrong amount of registers")
+	}
+	return d.readInput(THIRTYTWO_BITS), nil
+}
+
+// Get the current reading for a specific ShiftPin.
+func (p ShiftPin) Get() bool {
+	return (p.d.readInput(p.d.bits) & (1 << int(p.pin))) > 0
+}
+
+// Configure here just for interface compatibility.
+func (p ShiftPin) Configure() {
+}
+
+// readInput reads howMany bits from the shift register
+func (d *Device) readInput(howMany NumberBit) uint32 {
+	d.latch.High()
+	var data uint32
+	for i := howMany - 1; i >= 0; i-- {
+		d.clk.Low()
+		if d.out.Get() {
+			data |= 1 << i
+		}
+		d.clk.High()
+	}
+	d.latch.Low()
+	return data
+}