lcd_module.c

PIC_Hi-Tech_C_Mike_Pearces_I2C_routines Microchi PIC_Hi-Tech C_I2C_for_EEPROM_24LC01B Code

#include  <stdio.h>     
#include <ctype.h>
#include  <stdlib.h>    

// write a string to Optrex  8x2 LCD
// Interface is 4-bit 
// LCD:       PIC
// DB7-DB4 to RB7-RB4
// E       to RA5
// R/W     to RC1
// RS      to RC2
// Vdd     to Vdd
// Vss     to Vss
// VL      to Vss
// on LCD pins DB3-DB0, K, A are left unconnected

// macros to isolate interface dependencies
#define EHIGH          RA5=1
#define ELOW           RA5=0
#define E_OUTPUT       {ADCON1=0x06;TRISA5 = 0;}
#define RSHIGH         RB5=1
#define RSLOW          RB5=0
#define RS_OUTPUT      TRISB5 = 0
#define RWHIGH         RB4=1
#define RWLOW          RB4=0
#define RW_OUTPUT      TRISB4 = 0
#define BUSY_FLAG      RA3
#define DATA_DIR_RD    {TRISA3=1;TRISA2=1;\
                        TRISA1=1;TRISA0=1;}
#define DATA_DIR_WR    {TRISA3=0;TRISA2=0;\
                       TRISA1=0;TRISA0=0;}
#define OUTPUT_DATA(x) {PORTA = x;}



void epulse(void){
  DelayUs(1);  EHIGH;  DelayUs(1); ELOW; DelayUs(1);
}
void lcd_write(
     unsigned char cmd, unsigned char data_flag, unsigned char chk_busy, unsigned char dflag){
  char bflag,c;
  if (chk_busy) {    RSLOW;       //RS = 0 to check busy
    // check busy
    DATA_DIR_RD;  //set data pins all inputs
    RWHIGH;       // R/W = 1, for read
    do {
      EHIGH; DelayUs(1);  // upper 4 bits
      bflag = BUSY_FLAG;  
      ELOW; DelayUs(1);
      epulse();
    } while(bflag);
  } else {
    DelayMs(10); // don't use busy, just delay
  }
  DATA_DIR_WR;
  if (data_flag)  RSHIGH;   // RS=1, data byte
  else    RSLOW;   // RS=0, command byte
  // device is not busy
  RWLOW;       // R/W = 0, for write
  c = cmd >> 4;  // send upper 4 bits
  OUTPUT_DATA(c);
  epulse();
  if (dflag) {
    c = cmd & 0x0F;  //send lower 4 bits
    OUTPUT_DATA(c);
    epulse();
  }
}

void lcd_init(void) {
#if   defined(__18CXX)
  stdout = _H_USER;          // assign STDOUT to LCD
#endif

  DelayMs(50);  //wait for device to settle
  lcd_write(0x20,0,0,0);  // 4 bit interface
  lcd_write(0x28,0,0,1);  // 2 line display, 5x7 font
  lcd_write(0x28,0,0,1);  // repeat
  lcd_write(0x06,0,0,1);  // enable display
  lcd_write(0x0C,0,0,1);  // turn display on; cursor, blink is off
  lcd_write(0x01,0,0,1);  // clear display, move cursor to home
  DelayMs(50);   // wait for busy flag to be ready
}


#ifndef SERIAL_PUTCH
// send 8 bit char to LCD
void putch (char c) {
    lcd_write(c,1,1,1);
}

#if defined(__18CXX)
void _user_putc (auto char c) {
    putch (c);
}
#endif

#endif

#define LCD_PUTCH 1