lcd.c File Reference

lcd driver for Xmega More...

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

Functions
void	lcd_init (void)
	Initialize the lcd. More...
void	lcd_putc (char c)
	Writes a character to the LCD. More...
void	lcd_cmd (uint8_t cmd)
	Writes a command char to the LCD. More...
void	lcd_data (uint8_t b)
	Writes a data byte to the LCD. More...
void	lcd_puts (char *s)
	Writes a string to the LCD. More...
void	lcd_gotoxy (uint8_t x, uint8_t y)
	Set cursor to specified position. More...
void	lcd_clear (void)
	Clear lcd. More...
void	lcd_home (void)
	Cursor to home position. More...

Variables
volatile uint8_t	lcd_line = 0
	Current line number (0 is first line)

Detailed Description

lcd driver for Xmega

Author

Wim Dolman (w.e.dolman@hva.nl)

Date

21-10-2013

Version

1.0

This file contains the routines for interfacing a HD44780U-based text lcd display for Atmel Xmega devices.

It is based on the lcd libray from Peter Fleury (http://homepage.hispeed.ch/peterfleury/) for the ATmega devices.

This library is suitable for four different io modes:

• 8 bit mode without busyflag using connections D7..D0, RS and E
• 8 bit mode with busyflag using connections D7..D0, RS, E and R/W
• 4 bit mode without busyflag using connections D7..D4, RS and E
• 4 bit mode with busyflag using connections D7..D4, RS, E and R/W

There are defines for these four modes:

• LCD_4BIT_MODE 1 is 4 bit mode, 0 is 8 bit mode
• LCD_BUSY_FLAG 1 is with busyflag, 0 is without busyflag

In 8 bit mode all 8 data pins must be connected to one 8-pin port of the Xmega. In 4 bit mode all 4 data pins must be connected to one port of Xmega, but the 4 data lines may be connected to any pin of that port and in any order. The header file lcd.h contains macro definitions that can be for that purpose.

The control lines RS, E and R/W can connected to any pin of any port of the Xmega.

Warning

Be careful using the busyflag. Most alfanumeric displays are 5 Volt devices. Xmega's are not 5 Volt tolerant. When using the busyflag, information is also send from the LCD to the Xmega. So you can damage your Xmega.

Function Documentation

void lcd_clear

(

void

)

Clear lcd.

This function clears the LCD and sets cursor to home position.

Returns

none

void lcd_cmd

(

uint8_t

cmd

)

Writes a command char to the LCD.

This function writes a command char to the LCD.

Parameters

cmd	command character

Returns

none

void lcd_data

(

uint8_t

b

)

Writes a data byte to the LCD.

This function writes a data byte to the LCD.

Parameters

b

data byte

Returns

none

void lcd_gotoxy	(	uint8_t	x,
		uint8_t	y
	)

Set cursor to specified position.

This function sets the cursor to the specified position.

Parameters

x	horizontal position (0: left most position)
y	vertical position (0: first line)

Returns

none

void lcd_home

(

void

)

Cursor to home position.

This function sets cursor to home position.

Returns

none

void lcd_init

(

void

)

Initialize the lcd.

This function initializes the LCD in one of the four modes depending on de values of LCD_4BIT_MODE and LCD_BUSY_FLAG in the header file.

Returns

none

void lcd_putc

(

char

c

)

Writes a character to the LCD.

This function writes a character to the LCD. The characters '\n' and '\f' have a special meaning

• '\n' (new line) : go to the start of the next line
• '\f' (formfeed) : clears display and start at the home position

Parameters

c	the character to be written

Returns

none

void lcd_puts

(

char *

s

)

Writes a string to the LCD.

This function writes a character string to the LCD.

Parameters

s	pointer to the character string

Returns

none