lcd-api.c

/****************************************************************************
 *
 *   Copyright (c) 2006 Dave Hylands     <dhylands@gmail.com>
 *
 *   This program is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License version 2 as
 *   published by the Free Software Foundation.
 *
 *   Alternatively, this software may be distributed under the terms of BSD
 *   license.
 *
 *   See README and COPYING for more details.
 *
 ****************************************************************************/
/**
 *
 *   @file   lcd.c
 *
 *   @brief  Provides an API for talking to character style LCDs. These
 *           functions are designed around the HD44780 based LCD Controllers.
 *
 ****************************************************************************/
/**
 *
 *   This particular file doesn't know how to interface with the hardware.
 *
 *   It expects the following routines to be defined:
 *
 *       LCD_HAL_Write           - Writes a command or data byte to the hardware
 *       LCD_HAL_Delay           - Delays for a specified number of milliseconds
 *
 *   Currently, we don't support reading of the LCD or busy bit, instead
 *   just waiting for the maximum amount of time for each command.
 *
 ****************************************************************************/

/* ---- Include Files ----------------------------------------------------- */

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

#include "lcd.h"
#include "lcd-hal.h"

#if defined(AVR)
#else
#define pgm_read_byte(addr) *addr
#endif

/* ---- Public Variables -------------------------------------------------- */

/* ---- Private Constants and Types --------------------------------------- */

/* ---- Private Variables ------------------------------------------------- */

static uint8_t gNumLines;
static uint8_t gNumCols;
static uint8_t gX;
static uint8_t gY;

/* ---- Private Function Prototypes --------------------------------------- */

//***************************************************************************
/**
 *   LCD_WriteCommand
 *
 *   Writes a "command" to the LCD.
 */

static inline void LCD_WriteCommand(uint8_t cmd) {
    LCD_HAL_Write(LCD_RS_CMD, cmd);

    if (cmd <= 3) {
        // The Home and Clear commands require a worst case delay of 4.1 msec

        LCD_HAL_Delay(5);
    } else {
        // All of the rest of the commands require 160 usecs

        LCD_HAL_Delay(1);
    }

}  // LCD_WriteCommand

/* ---- Functions --------------------------------------------------------- */

//***************************************************************************
/**
 *   LCD_BlinkCursor
 *
 *   Controls whether the cursor is blinking or not. This function also has
 *   the side effect of causing the cursor to be "shown".
 */

void LCD_BlinkCursor(int onOff) {
    if (onOff) {
        LCD_WriteCommand(LCD_ON_CTRL | LCD_ON_DISPLAY | LCD_ON_CURSOR | LCD_ON_BLINK);
    } else {
        LCD_WriteCommand(LCD_ON_CTRL | LCD_ON_DISPLAY | LCD_ON_CURSOR);
    }

}  // LCD_BlinkCursor

//***************************************************************************
/**
 *   LCD_Clear
 *
 *   Clears the LCD display and moves the cursor to the top left corner
 */

void LCD_Clear(void) {
    LCD_WriteCommand(LCD_CLR);
    LCD_WriteCommand(LCD_HOME);

    gX = 0;
    gY = 0;

}  // LCD_Clear

//***************************************************************************
/**
 *   LCD_DisplayOff
 *
 *   Turns off (i.e. blanks) the LCD.
 */

void LCD_DisplayOff(void) {
    LCD_WriteCommand(LCD_ON_CTRL);

}  // LCD_DisplayOff

//***************************************************************************
/**
 *   LCD_Display
 *
 *   Turns on (i.e. unblanks) the LCD.
 */

void LCD_DisplayOn(void) {
    LCD_WriteCommand(LCD_ON_CTRL | LCD_ON_DISPLAY);

}  // LCD_DisplayOn

//***************************************************************************
/**
 *   LCD_HideCursor
 *
 *   Causes the cursor to be hidden.
 */

void LCD_HideCursor(void) {
    LCD_WriteCommand(LCD_ON_CTRL | LCD_ON_DISPLAY);

}  // LCD_HideCursor

//***************************************************************************
/**
 *   LCD_Init
 *
 *   Initializes the LCD for use.
 */

void LCD_Init(uint8_t numLines, uint8_t numCols) {
    if (numLines > 4) {
        numLines = 4;
    }
    gNumLines = numLines;

    if (numCols > 40) {
        numCols = 40;
    }
    gNumCols = numCols;

    // Let the low level HAL do most of the initialization

    LCD_HAL_Init();

    LCD_DisplayOff();

    LCD_Clear();

    LCD_WriteCommand(LCD_ENTRY_MODE | LCD_ENTRY_INC);

    LCD_HideCursor();  // also turns on display

}  // LCD_Init

//***************************************************************************
/**
 *   LCD_MoveTo
 *
 *   Moves the cursor position to the indicated position. x=0 is the first
 *   column, y=0 is the first row.
 */

void LCD_MoveTo(unsigned x, unsigned y) {
    uint8_t addr = x & 0x3f;

    if (y & 1) {
        addr += 0x40;  // Lines 1 & 3 add 0x40
    }
    if (y & 2) {
        addr += 0x14;  // Lines 2 & 3 add 0x14
    }

    LCD_WriteCommand(LCD_DDRAM | addr);

    gX = x;
    gY = y;

}  // LCD_MoveTo

//***************************************************************************
/**
 *   LCD_NumCols
 *
 *   Returns the number of columns passed into LCD_Init.
 */

uint8_t LCD_NumCols(void) {
    return gNumCols;

}  // LCD_NumCols

//***************************************************************************
/**
 *   LCD_NumLines
 *
 *   Returns the number of rows passed into LCD_Init.
 */

uint8_t LCD_NumLines(void) {
    return gNumLines;

}  // LCD_NumLines

//***************************************************************************
/**
 *   LCD_PutChar
 *
 *   Writes the inidcated character to the LCD at the current cursor position
 *   and advances the cursor by one position.
 */

void LCD_PutChar(char ch) {
    if ((gX >= gNumCols) || (ch == '\n')) {
        gX = 0;
        gY++;

        if (gY >= gNumLines) {
            gY = 0;
        }

        LCD_MoveTo(gX, gY);
    }
    if (ch != '\n') {
        LCD_HAL_Write(LCD_RS_DATA, ch);
        LCD_HAL_Delay(1);

        gX++;
    }

}  // LCD_PutChar

//***************************************************************************
/**
 *   LCD_PutStr
 *
 *   Writes the indicated string to the LCD at the current cursor position
 *   and advances the cursor by the length of the string.
 */

void LCD_PutStr_P(const char* s) {
    char ch;

    while ((ch = pgm_read_byte(s)) != '\0') {
        LCD_PutChar(ch);

        s++;
    }

}  // LCD_PutStr

//***************************************************************************
/**
 *   LCD_ShowCurosr
 *
 *   Causes the cursor to be made visible.
 */

void LCD_ShowCursor(void) {
    LCD_WriteCommand(LCD_ON_CTRL | LCD_ON_DISPLAY | LCD_ON_CURSOR);

}  // LCD_ShowCursor