init.go

package lcd

import (
	"fmt"
	"sync"
	"time"
)

func (l *LCD) init4Bit() {
	l.write4BitHigh(0b00100000) // 4-bit mode - N/F flags ignored

	// from here we can send high then low nibble
	if l.lines > 1 {
		l.write4Bit(0b00101000 | (byte(l.fontSize) << 2)) // 4 bit, 2 lines, 5x8
	} else {
		l.write4Bit(0b00100000 | (byte(l.fontSize) << 2)) // 4 bit, 1 line, 5x8
	}
}

func (l *LCD) init8Bit() {
	if l.lines > 1 {
		l.write8Bit(0b00111000 | (byte(l.fontSize) << 2)) // 8-bit mode, 2 lines, 5x8
	} else {
		l.write8Bit(0b00110000 | (byte(l.fontSize) << 2)) // 8-bit mode, 2 lines, 5x8
	}
}

func (l *LCD) init() {

	l.pins.init()

	l.pins.registerSelect.Low() // instruction

	l.write4BitHigh(0b00110000)
	time.Sleep(time.Millisecond * 10)

	l.write4BitHigh(0b00110000)
	time.Sleep(time.Microsecond * 200)

	l.write4BitHigh(0b00110000)
	time.Sleep(time.Millisecond * 10)

	if len(l.pins.data) == 4 {
		l.init4Bit()
	} else {
		l.init8Bit()
	}

	// Display OFF
	l.execInstruction(insSetDisplayMode, l.displayMode.byte())

	// Clear
	l.Clear()

	// Entry mode
	l.SetCursorIncrement(true)

	// Turn on!
	l.On()
}

func (l *LCD) Close() {
	if l.pins.readWrite == nil {
		l.pins.readWrite.Low()
	}
	l.pins.registerSelect.Low()
	for _, pin := range l.pins.data {
		pin.Low()
	}
	newMu.Lock()
	defer newMu.Unlock()
	newCount--
	if newCount == 0 {
		closeGPIO()
	}
}

var newMu sync.Mutex
var newCount int

// New opens communication with the LCD for further instruction
func New(columns, lines uint8, fontSize FontSize, registerSelect, enable, readWrite Pin, data ...Pin) (*LCD, error) {

	if len(data) != 4 && len(data) != 8 {
		return nil, fmt.Errorf("you must specify either 4 or 8 data pins")
	}

	newMu.Lock()
	defer newMu.Unlock()
	newCount++

	lcd := &LCD{
		columns:  columns,
		lines:    lines,
		fontSize: fontSize,
		pins: pins{
			registerSelect: registerSelect,
			enable:         enable,
			readWrite:      readWrite,
			data:           data,
		},
	}

	lcd.init()

	return lcd, nil
}