GPIO implements io readwriter interface, simplified display, smoke tests

hd44780/gpio.go

@@ -0,0 +1,148 @@
+package hd44780
+
+import (
+	"errors"
+
+	"machine"
+)
+
+type GPIO struct {
+	dataPins []machine.GPIO
+	e        machine.GPIO
+	rw       machine.GPIO
+	rs       machine.GPIO
+
+	write func(data byte)
+	read  func() byte
+}
+
+func newGPIO(dataPins []uint8, e, rs, rw uint8, mode byte) Device {
+
+	pins := make([]machine.GPIO, len(dataPins))
+	for i := 0; i < len(dataPins); i++ {
+		m := machine.GPIO{Pin: dataPins[i]}
+		m.Configure(machine.GPIOConfig{Mode: machine.GPIO_OUTPUT})
+		pins[i] = m
+	}
+	enable := machine.GPIO{e}
+	enable.Configure(machine.GPIOConfig{Mode: machine.GPIO_OUTPUT})
+	registerSelect := machine.GPIO{rs}
+	registerSelect.Configure(machine.GPIOConfig{Mode: machine.GPIO_OUTPUT})
+	readWrite := machine.GPIO{rw}
+	readWrite.Configure(machine.GPIOConfig{Mode: machine.GPIO_OUTPUT})
+	readWrite.Low()
+
+	gpio := GPIO{
+		dataPins: pins,
+		e:        enable,
+		rs:       registerSelect,
+		rw:       readWrite,
+	}
+
+	if mode == DATA_LENGTH_4BIT {
+		gpio.write = gpio.write4BitMode
+		gpio.read = gpio.read4BitMode
+	} else {
+		gpio.write = gpio.write8BitMode
+		gpio.read = gpio.read8BitMode
+	}
+
+	return Device{
+		bus:        &gpio,
+		datalength: mode,
+	}
+}
+
+// SetCommandMode sets command/instruction mode
+func (g *GPIO) SetCommandMode(set bool) {
+	if set {
+		g.rs.Low()
+	} else {
+		g.rs.High()
+	}
+}
+
+func (g *GPIO) Write(data []byte) (n int, err error) {
+	g.rw.Low()
+	for _, d := range data {
+		g.write(d)
+		n++
+	}
+	return n, nil
+}
+
+func (g *GPIO) write8BitMode(data byte) {
+	g.e.High()
+	g.setPins(data)
+	g.e.Low()
+}
+
+func (g *GPIO) write4BitMode(data byte) {
+	g.e.High()
+	g.setPins(data >> 4)
+	g.e.Low()
+
+	g.e.High()
+	g.setPins(data)
+	g.e.Low()
+}
+
+func (g *GPIO) Read(data []byte) (n int, err error) {
+	if len(data) == 0 {
+		return 0, errors.New("Length greater than 0 is required")
+	}
+	g.rs.Low()
+	g.rw.High()
+	g.reconfigureGPIOMode(machine.GPIO_INPUT)
+	for i := 0; i < len(data); i++ {
+		data[i] = g.read()
+		n++
+	}
+	g.reconfigureGPIOMode(machine.GPIO_OUTPUT)
+	return n, nil
+}
+
+func (g *GPIO) read4BitMode() byte {
+	g.e.High()
+	data := (g.pins() << 4 & 0xF0)
+	g.e.Low()
+	g.e.High()
+	data |= (g.pins() & 0x0F)
+	g.e.Low()
+	return data
+}
+func (g *GPIO) read8BitMode() byte {
+	g.e.High()
+	data := g.pins()
+	g.e.Low()
+	return data
+}
+func (g *GPIO) reconfigureGPIOMode(mode machine.GPIOMode) {
+	for i := 0; i < len(g.dataPins); i++ {
+		g.dataPins[i].Configure(machine.GPIOConfig{Mode: mode})
+	}
+}
+
+// setPins sets high or low state on all data pins depending on data
+func (g *GPIO) setPins(data byte) {
+	mask := byte(1)
+	for i := 0; i < len(g.dataPins); i++ {
+		if (data & mask) != 0 {
+			g.dataPins[i].High()
+		} else {
+			g.dataPins[i].Low()
+		}
+		mask = mask << 1
+	}
+}
+
+// pins returns current state of data pins. MSB is D7
+func (g *GPIO) pins() byte {
+	bits := byte(0)
+	for i := uint8(0); i < uint8(len(g.dataPins)); i++ {
+		if g.dataPins[i].Get() {
+			bits |= (1 << i)
+		}
+	}
+	return bits
+}