lcd.c

利用热释红外传感器、12C887和PIC单片机制作的智能电子时钟

/*
 *  LCD interface example
 *  Uses routines from delay.c
 *  This code will interface to a standard LCD controller
 *  like the samsung KS0066. It uses it in 4 bit mode, with
 *  the hardware connected as follows (the standard 16 pin
 *  LCD connector is used):
 *
 *  PORTC bits 4-7 are connected to the LCD data bits 4-7 (high nibble)
 *  PORTA bit 1 is connected to the LCD RS input (register select)
 *  PORTA bit 2 is connected to the LCD EN bit (enable)
 *
 *  To use these routines, set up the port I/O (TRISC, TRISB) then
 *  call lcd_init(), then other routines as required.
 *
 */

#include <pic.h>
#include "lcd.h"
#include "delay.h"

#define TLCD_RS  TRISA1
#define TLCD_EN  TRISA2
#define TLCD_A   TRISA3
#define LCD_RS   RA1   // 寄存器选择
#define LCD_EN   RA2   // 使能
#define LCD_A    RA3   // 背光,RA4开漏输出,欲输出1,需要外接上拉电阻

#define LCD_STROBE  ((LCD_EN = 1),(LCD_EN=0))
#define LCD_CURSOR(x)   lcd_write(((x)&0x7F)|0x80)

/* light lcd & dark*/

void lcd_light(void)
{
    LCD_A = 0;
}

void lcd_dark(void)
{
    LCD_A = 1;
}


/* write a byte to the LCD in 4 bit mode */

void lcd_write(unsigned char c)
{
    PORTC = (PORTC & 0x0F) |  (c &0xF0);
    LCD_STROBE;
    PORTC = (PORTC & 0x0F) |  (c<<4);
    LCD_STROBE;
    DelayUs(40);
}

/* Clear and home the LCD */

void lcd_clear(void)
{
    LCD_RS = 0;
    lcd_write(0x1);
    DelayMs(2);
}

/* write a string of chars to the LCD */

void lcd_puts(const char * s)
{
    LCD_RS = 1; // write characters
    while(*s)//当S的值不为0时,执行,故,需要花一个RAM,将其清0作为整个字符数组的结束标记
    {
        lcd_write(*s++);
    }
}


/* write one character to the LCD */

void lcd_putch(char c)
{
    LCD_RS = 1; // write characters
    PORTC = (PORTC & 0x0F) |  (c &0xF0);
    LCD_STROBE;
    PORTC = (PORTC & 0x0F) |  (c<<4);
    LCD_STROBE;
    DelayUs(40);
}

/* Go to the specified position */

void lcd_goto(unsigned char pos)
{
    LCD_RS = 0;
    LCD_CURSOR(pos);
}

/* initialise the LCD - put into 4 bit mode */
#ifndef SPLC780D
void lcd_init(void)
{

    TLCD_RS = 0;
    TLCD_EN = 0;
    TLCD_A  = 0;
    LCD_RS = 0;
    LCD_EN = 0;
    LCD_A  = 0;
    LCD_RS = 0;         // write control bytes
    lcd_write(0x2);     // return home
    DelayMs(2);
    lcd_write(0x28);    // 4 bit mode, 2 lines, 5x7 font
    lcd_write(0x0C);    // display on, curson off, blink off
    lcd_clear();        // clear display
    lcd_write(0x06);    // right, increment address
}
#else
void lcd_init(void)
{

    TLCD_RS = 0;
    TLCD_EN = 0;
    TLCD_A  = 0;
    LCD_RS = 0;
    LCD_EN = 0;
    LCD_A  = 0;
    LCD_RS = 0;         // write control bytes
    lcd_write(0b00000010);  // return home
    DelayMs(10);
    lcd_write(0b00111111);  // 8 bit interface
    DelayMs(10);
    lcd_write(0b00111111);  // 8 bit interface
    DelayMs(10);
    lcd_write(0b00101000);  // 4 bit interface,2 lines,5*8
    DelayMs(10);
    lcd_write(0b00001100);  // dispaly on
    DelayMs(10);
    lcd_write(0b00000001);  // clear LCD
    DelayMs(10);
    lcd_write(0b00000110);  // entry mode set
    DelayMs(10);
}
#endif