/* File: lcd.c Version: 0.1.0 Date: Feb. 25, 2006 C header file for HD44780 LCD module using a 74HCT164 serial in, parallel out out shift register to operate the LCD in 8-bit mode. Example schematic usuing a Powertip PC-1202A LCD available at http://www.micahcarrick.com Uses the avr-libc library for gcc (avr-gcc). **************************************************************************** Copyright (C) 2006 Micah Carrick This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. This program 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 General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA **************************************************************************** */ #include "lcd.h" #include #include #include #include /* * Turns the backlight on or off. The LCD_BACKLIGHT_PIN should be defined as * the pin connected to the backlight control of the LCD. * * Parameters: * backlight_on 0=off, 1=on */ /* void lcd_backlight(int backlight_on) { if (backlight_on) { LCD_PORT |= _BV(LCD_BACKLIGHT_PIN); } else { LCD_PORT &= ~_BV(LCD_BACKLIGHT_PIN); } } */ /* * Initializes the LCD. Should be called during the initialization of the * program. * * Parameters: * set_function See LCD_FUNCTION_* definitions in lcd.h * set_entry_mode See LCD_CMD_ENTRY_* definitions in lcd.h * on See LCD_CMD_ON_* definitions in lcd.h */ void lcd_initialize(uint8_t set_function, uint8_t set_entry_mode, uint8_t on) { /* 20ms delay while LCD powers on */ _delay_ms(16); /* Write 0x30 to LCD and wait 5 mS for the instruction to complete */ lcd_load_byte(0x30); lcd_send_cmd(); _delay_ms(5); /* Write 0x30 to LCD and wait 160 uS for instruction to complete */ lcd_load_byte(0x30); lcd_send_cmd(); _delay_us(120); /* Write 0x30 AGAIN to LCD and wait 160 uS */ lcd_load_byte(0x30); lcd_send_cmd(); _delay_us(120); /* Set function and wait 40uS */ lcd_load_byte(set_function); lcd_send_cmd(); /* Turn off the display and wait 40uS */ lcd_load_byte(LCD_CMD_OFF); lcd_send_cmd(); /* Clear display and wait 1.64mS */ lcd_load_byte(LCD_CMD_CLEAR); lcd_send_cmd(); _delay_ms(2); /* Set entry mode and wait 40uS */ lcd_load_byte(set_entry_mode); lcd_send_cmd(); /* Turn display back on and wait 40uS */ lcd_load_byte(on); lcd_send_cmd(); }; /* * Loads a byte into the shift register (74'164). Does NOT load into the LCD. * * Parameters: * out_byte The byte to load into the '164. */ void lcd_load_byte(uint8_t out_byte) { /* make sure clock is low */ LCD_PORT &= ~_BV(LCD_CLOCK_PIN); int i; for(i=0; i<8; i++) { /* loop through bits */ if (out_byte & 0x80) { /* this bit is high */ LCD_PORT |=_BV(LCD_RSDS_PIN); } else { /* this bit is low */ LCD_PORT &= ~_BV(LCD_RSDS_PIN); } out_byte = out_byte << 1; /* pulse the the shift register clock */ LCD_PORT |= _BV(LCD_CLOCK_PIN); LCD_PORT &= ~_BV(LCD_CLOCK_PIN); } } /* * Loads the byte in the '164 shift register into the LCD as a command. The * '164 should already be loaded with the data using lcd_load_byte(). */ void lcd_send_cmd(void) { /* Data in '164 is a command, so RS must be low (0) */ LCD_PORT &= ~_BV(LCD_RSDS_PIN); lcd_strobe_E(); _delay_us(40); } /* * Loads the byte in the '164 shift register into the LCD as a character. The * '164 should already be loaded with the data using lcd_load_byte(). */ void lcd_send_char(void) { /* Data in '164 is a character, so RS must be high (1) */ LCD_PORT |= _BV(LCD_RSDS_PIN); lcd_strobe_E(); _delay_us(40); } /* * Loads the byte into the shift register and then sends it to the LCD as a char * Parameters: * c The byte (character) to display */ void lcd_putc(char c) { lcd_load_byte(c); lcd_send_char(); } /* * Strobes the E signal on the LCD to "accept" the byte in the '164. The RS * line determines wheter the byte is a character or a command. */ void lcd_strobe_E(void) { /* strobe E signal */ LCD_PORT |= _BV(LCD_ENABLE_PIN); _delay_us(450); LCD_PORT &= ~_BV(LCD_ENABLE_PIN); } /* * Moves the cursor to the home position. */ void lcd_cursor_home() { lcd_load_byte(LCD_CMD_HOME); lcd_send_cmd(); } /* * Moves the cursor to the specified position. * Parameters: * line Line (row) * pos Position on that line (column) */ void lcd_move_cursor(uint8_t line, uint8_t pos) { lcd_load_byte(line+pos); lcd_send_cmd(); } /* * Moves the cursor a number of spaces to the right * Parameters: * spaces Number of spaces to move */ void lcd_inc_cursor(uint8_t spaces) { while (spaces--) { lcd_load_byte(LCD_CMD_CURSOR_RIGHT); lcd_send_cmd(); } } /* * Moves the cursor a number of spaces to the left * Parameters: * spaces Number of spaces to move */ void lcd_dec_cursor(uint8_t spaces) { while (spaces--) { lcd_load_byte(LCD_CMD_CURSOR_LEFT); lcd_send_cmd(); } } void lcd_puts(char p[]) { int x=0; while (p[x]!='\0') { lcd_putc(p[x]); x++; } } /* void lcd_puts_P(const char *p) { char c; while ((c = pgm_read_byte(p++)) != 0) { lcd_putc(c); } } */