CoffeePi/CoffeeCode/lcd.cpp

/*
 * lcd.c:
 *	Text-based LCD driver.
 *	This is designed to drive the parallel interface LCD drivers
 *	based in the Hitachi HD44780U controller and compatables.
 *
 * Copyright (c) 2012 Gordon Henderson.
 ***********************************************************************
 * This file is part of wiringPi:
 *	https://projects.drogon.net/raspberry-pi/wiringpi/
 *
 *    wiringPi is free software: you can redistribute it and/or modify
 *    it under the terms of the GNU Lesser General Public License as published by
 *    the Free Software Foundation, either version 3 of the License, or
 *    (at your option) any later version.
 *
 *    wiringPi is distributed in the hope that it will be useful,
 *    but WITHOUT ANY WARRANTY; without even the implied warranty of
 *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *    GNU Lesser General Public License for more details.
 *
 *    You should have received a copy of the GNU Lesser General Public License
 *    along with wiringPi.  If not, see <http://www.gnu.org/licenses/>.
 ***********************************************************************
 */

#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>

#include <wiringPi.h>

#include "spi.h"
#include "lcd.h"

#ifndef	TRUE
#  define	TRUE	(1==1)
#  define	FALSE	(1==2)
#endif

// HD44780U Commands

#define	LCD_CLEAR	0x01
#define	LCD_HOME	0x02
#define	LCD_ENTRY	0x04
#define	LCD_CTRL	0x08
#define	LCD_CDSHIFT	0x10
#define	LCD_FUNC	0x20
#define	LCD_CGRAM	0x40
#define	LCD_DGRAM	0x80

// Bits in the entry register

#define	LCD_ENTRY_SH		0x01
#define	LCD_ENTRY_ID		0x02

// Bits in the control register

#define	LCD_BLINK_CTRL		0x01
#define	LCD_CURSOR_CTRL		0x02
#define	LCD_DISPLAY_CTRL	0x04

// Bits in the function register

#define	LCD_FUNC_F	0x04
#define	LCD_FUNC_N	0x08
#define	LCD_FUNC_DL	0x10

#define	LCD_CDSHIFT_RL	0x04

struct lcdDataStruct {
	int bits, rows, cols;
	int rsPin, strbPin;
	int cx, cy;
};

struct lcdDataStruct *lcds[MAX_LCDS];

static int lcdControl;

// Row offsets

static const int rowOff[4] = { 0x00, 0x40, 0x14, 0x54 };

/*
 * strobe:
 *	Toggle the strobe (Really the "E") pin to the device.
 *	According to the docs, data is latched on the falling edge.
 *********************************************************************************
 */

static void strobe(const struct lcdDataStruct *lcd) {

// Note timing changes for new version of delayMicroseconds ()

	digitalWrite(lcd->strbPin, 1);
	delayMicroseconds(50);
	digitalWrite(lcd->strbPin, 0);
	delayMicroseconds(50);
}

/*
 * sentDataCmd:
 *	Send an data or command byte to the display.
 *********************************************************************************
 */

static void sendDataCmd(const struct lcdDataStruct *lcd, unsigned char data) {
	register unsigned char myData = data;
	unsigned char i, d4;

	if (lcd->bits == 4) {
		d4 = (myData >> 4) & 0x0F;
		shift_data(d4);
		d4 >>= 4;
		strobe(lcd);

		d4 = myData & 0x0F;
		shift_data(d4);
	} else {
		shift_data(myData);
	}
	strobe(lcd);
}

/*
 * putCommand:
 *	Send a command byte to the display
 *********************************************************************************
 */

static void putCommand(const struct lcdDataStruct *lcd, unsigned char command) {
	digitalWrite(lcd->rsPin, 0);
	sendDataCmd(lcd, command);
	delay(2);
}

static void put4Command(const struct lcdDataStruct *lcd,
		unsigned char command) {
	register unsigned char myCommand = command;
	register unsigned char i;

	digitalWrite(lcd->rsPin, 0);
	shift_data(command & 0x0F);
	strobe(lcd);
}

/*
 *********************************************************************************
 * User Callable code below here
 *********************************************************************************
 */

/*
 * lcdHome: lcdClear:
 *	Home the cursor or clear the screen.
 *********************************************************************************
 */

void lcdHome(const int fd) {
	struct lcdDataStruct *lcd = lcds[fd];

	putCommand(lcd, LCD_HOME);
	lcd->cx = lcd->cy = 0;
	delay(5);
}

void lcdClear(const int fd) {
	struct lcdDataStruct *lcd = lcds[fd];

	putCommand(lcd, LCD_CLEAR);
	putCommand(lcd, LCD_HOME);
	lcd->cx = lcd->cy = 0;
	delay(5);
}

/*
 * lcdDisplay: lcdCursor: lcdCursorBlink:
 *	Turn the display, cursor, cursor blinking on/off
 *********************************************************************************
 */

void lcdDisplay(const int fd, int state) {
	struct lcdDataStruct *lcd = lcds[fd];

	if (state)
		lcdControl |= LCD_DISPLAY_CTRL;
	else
		lcdControl &= ~LCD_DISPLAY_CTRL;

	putCommand(lcd, LCD_CTRL | lcdControl);
}

void lcdCursor(const int fd, int state) {
	struct lcdDataStruct *lcd = lcds[fd];

	if (state)
		lcdControl |= LCD_CURSOR_CTRL;
	else
		lcdControl &= ~LCD_CURSOR_CTRL;

	putCommand(lcd, LCD_CTRL | lcdControl);
}

void lcdCursorBlink(const int fd, int state) {
	struct lcdDataStruct *lcd = lcds[fd];

	if (state)
		lcdControl |= LCD_BLINK_CTRL;
	else
		lcdControl &= ~LCD_BLINK_CTRL;

	putCommand(lcd, LCD_CTRL | lcdControl);
}

/*
 * lcdSendCommand:
 *	Send any arbitary command to the display
 *********************************************************************************
 */

void lcdSendCommand(const int fd, unsigned char command) {
	struct lcdDataStruct *lcd = lcds[fd];
	putCommand(lcd, command);
}

/*
 * lcdPosition:
 *	Update the position of the cursor on the display.
 *	Ignore invalid locations.
 *********************************************************************************
 */

void lcdPosition(const int fd, int x, int y) {
	struct lcdDataStruct *lcd = lcds[fd];

	if ((x > lcd->cols) || (x < 0))
		return;
	if ((y > lcd->rows) || (y < 0))
		return;

	putCommand(lcd, x + (LCD_DGRAM | rowOff[y]));

	lcd->cx = x;
	lcd->cy = y;
}

/*
 * lcdCharDef:
 *	Defines a new character in the CGRAM
 *********************************************************************************
 */

void lcdCharDef(const int fd, int index, unsigned char data[8]) {
	struct lcdDataStruct *lcd = lcds[fd];
	int i;

	putCommand(lcd, LCD_CGRAM | ((index & 7) << 3));

	digitalWrite(lcd->rsPin, 1);
	for (i = 0; i < 8; ++i)
		sendDataCmd(lcd, data[i]);
}

/*
 * lcdPutchar:
 *	Send a data byte to be displayed on the display. We implement a very
 *	simple terminal here - with line wrapping, but no scrolling. Yet.
 *********************************************************************************
 */

void lcdPutchar(const int fd, unsigned char data) {
	struct lcdDataStruct *lcd = lcds[fd];

	digitalWrite(lcd->rsPin, 1);
	sendDataCmd(lcd, data);

	if (++lcd->cx == lcd->cols) {
		lcd->cx = 0;
		if (++lcd->cy == lcd->rows)
			lcd->cy = 0;

		putCommand(lcd, lcd->cx + (LCD_DGRAM | rowOff[lcd->cy]));
	}
}

/*
 * lcdPuts:
 *	Send a string to be displayed on the display
 *********************************************************************************
 */

void lcdPuts(const int fd, const char *string) {
	while (*string)
		lcdPutchar(fd, *string++);
}

/*
 * lcdPrintf:
 *	Printf to an LCD display
 *********************************************************************************
 */

void lcdPrintf(const int fd, const char *message, ...) {
	va_list argp;
	char buffer[1024];

	va_start (argp, message);
	vsnprintf(buffer, 1023, message, argp);
	va_end (argp);

	lcdPuts(fd, buffer);
}

/*
 * lcdInit:
 *	directly initialises the LCD for the CoffeePi
 *********************************************************************************
 */

int lcdInit(void) {
	spi_init();
	shift_init();
	pinMode(LCD_RW, OUTPUT);
	digitalWrite(LCD_RW, LOW);
	return lcdInitI(2, 16, 8, LCD_RS, LCD_EN);
}

/*
 * lcdInit:
 *	Take a lot of parameters and initialise the LCD, and return a handle to
 *	that LCD, or -1 if any error.
 *********************************************************************************
 */

int lcdInitI(const int rows, const int cols, const int bits, const int rs,
		const int strb) {
	static int initialised = 0;

	unsigned char func;
	int i;
	int lcdFd = -1;
	struct lcdDataStruct *lcd;

	if (initialised == 0) {
		initialised = 1;
		for (i = 0; i < MAX_LCDS; ++i)
			lcds[i] = NULL;
	}

// Simple sanity checks

	if (!((bits == 4) || (bits == 8)))
		return -1;

	if ((rows < 0) || (rows > 20))
		return -1;

	if ((cols < 0) || (cols > 20))
		return -1;

// Create a new LCD:

	for (i = 0; i < MAX_LCDS; ++i) {
		if (lcds[i] == NULL) {
			lcdFd = i;
			break;
		}
	}

	if (lcdFd == -1)
		return -1;

	lcd = (struct lcdDataStruct *) malloc(sizeof(struct lcdDataStruct));
	if (lcd == NULL)
		return -1;

	lcd->rsPin = rs;
	lcd->strbPin = strb;
	lcd->bits = 8;		// For now - we'll set it properly later.
	lcd->rows = rows;
	lcd->cols = cols;
	lcd->cx = 0;
	lcd->cy = 0;

	lcds[lcdFd] = lcd;

	digitalWrite(lcd->rsPin, 0);
	pinMode(lcd->rsPin, OUTPUT);
	digitalWrite(lcd->strbPin, 0);
	pinMode(lcd->strbPin, OUTPUT);

	delay(35); // mS

// 4-bit mode?
//	OK. This is a PIG and it's not at all obvious from the documentation I had,
//	so I guess some others have worked through either with better documentation
//	or more trial and error... Anyway here goes:
//
//	It seems that the controller needs to see the FUNC command at least 3 times
//	consecutively - in 8-bit mode. If you're only using 8-bit mode, then it appears
//	that you can get away with one func-set, however I'd not rely on it...
//
//	So to set 4-bit mode, you need to send the commands one nibble at a time,
//	the same three times, but send the command to set it into 8-bit mode those
//	three times, then send a final 4th command to set it into 4-bit mode, and only
//	then can you flip the switch for the rest of the library to work in 4-bit
//	mode which sends the commands as 2 x 4-bit values.

	if (bits == 4) {
		func = LCD_FUNC | LCD_FUNC_DL;			// Set 8-bit mode 3 times
		put4Command(lcd, func >> 4);
		delay(35);
		put4Command(lcd, func >> 4);
		delay(35);
		put4Command(lcd, func >> 4);
		delay(35);
		func = LCD_FUNC;					// 4th set: 4-bit mode
		put4Command(lcd, func >> 4);
		delay(35);
		lcd->bits = 4;
	} else {
		func = LCD_FUNC | LCD_FUNC_DL;
		putCommand(lcd, func);
		delay(35);
		putCommand(lcd, func);
		delay(35);
		putCommand(lcd, func);
		delay(35);
	}

	if (lcd->rows > 1) {
		func |= LCD_FUNC_N;
		putCommand(lcd, func);
		delay(35);
	}

// Rest of the initialisation sequence

	lcdDisplay(lcdFd, TRUE);
	lcdCursor(lcdFd, FALSE);
	lcdCursorBlink(lcdFd, FALSE);
	lcdClear(lcdFd);

	putCommand(lcd, LCD_ENTRY | LCD_ENTRY_ID);
	putCommand(lcd, LCD_CDSHIFT | LCD_CDSHIFT_RL);

	return lcdFd;
}