lcd driver

gistfile1.c

#include <avr/io.h>
#include <avr/pgmspace.h>
#include <util/delay.h>
#include "lcd.h"

#define BUSY_FLAG 0b10000000

void wait();

char read(void)
{
	char low, high;

	en(1);
	_delay_us(100);
	high = read_nible();
	en(0);
	_delay_us(50);
	en(1);
	_delay_us(100);
	low = read_nible();
	en(0);
	return high | (low >> 4);
}

void write(char data)
{
	char high = data >> 4, low = data;

	write_nible(high);
	en(1);
	_delay_us(100);
	en(0);

	write_nible(low);
	en(1);
	_delay_us(100);
	en(0);
}

void lcd_clear_display(void)
{
	wait();
	rs_ws(0, 0);
	write(0b00000001);
}

void lcd_return_home(void)
{
	wait();
	rs_ws(0, 0);
	write(0b00000010);
}

void lcd_entry_mode_set(char incr_decr, char shift)
{
	wait();
	rs_ws(0, 0);
	write(0b00000100 | (incr_decr << 1) | shift);
}

void lcd_display_on_off_control(char display, char cursor, char blink)
{
	wait();
	rs_ws(0, 0);
	write(0b00001000 | (display << 2) | (cursor << 1) | blink);
}

void lcd_cursor_display_shift(char s_c, char r_l)
{
	wait();
	rs_ws(0, 0);
	write(0b00010000 | (s_c << 3) | (r_l << 2));
}

void lcd_function_set(char lines, char font)
{
	char data_len = 0; /* we're only support 4bit mode of operation */
	wait();
	rs_ws(0, 0);
	write(0b00100000 | (data_len << 4) | (lines << 3) | (font << 2));
}


void
lcd_set_cgram_addr(char addr)
{
	wait();
	rs_ws(0, 0);
	write(0b01000000 | (addr & 0b00111111));
}


void
lcd_set_ddram_addr(char addr)
{
	wait();
	rs_ws(0, 0);
	write(0b10000000 | (addr & 0b01111111));
}

/* read BusyFlag and AddressCounter */
char lcd_read_bf_ac(void)
{
	rs_ws(0, 1);
	return read();
}

void wait()
{
	_delay_ms(1);
	for (;;) {
		if ((lcd_read_bf_ac() & BUSY_FLAG) == 0)
			break;
	}
}

#define lcd_putc lcd_write_data
void lcd_write_data(char data)
{
	wait();
	rs_ws(1, 0);
	write(data);
}

char lcd_read_data(void)
{
	wait();
	rs_ws(1, 1);
	return read();
}

void lcd_init(char lines, char font)
{
	rs_ws(0, 0);
	write_nible(0b0011); /* Function Set: 8bit interface */

	en(1);
	_delay_us(500);
	en(0);
	_delay_ms(5);


	en(1);
	_delay_us(500);
	en(0);
	_delay_ms(5);

	en(1);
	_delay_us(500);
	en(0);
	_delay_ms(5);



	rs_ws(0, 0);
	write_nible(0b0010); /* Function Set: 4bit interface, 8bit write */
	en(1);
	_delay_us(500);
	en(0);
	_delay_ms(5);

	write(0b00100000 | (lines << 3) | (font << 2)); /* Function Set 4bit, lines, font */
}




void
lcd_puts(char *message)
{
	while(*message)
		lcd_putc(*message++);
}

void
lcd_puts_P(char *message)
{
	char b;
	while((b = pgm_read_byte(message++)))
		lcd_putc(b);
}