f_8_25_lcd_lines_4bit.c

* Use 10 MHz crystal frequency. * Use Timer0 for ten millisecond looptime. * Blink "Alive" LED e

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

#include "delay.h"

// macros to isolate interface dependencies
#define EHIGH          RA2=1
#define ELOW           RA2=0
#define E_OUTPUT       {ADCON1=0x06;TRISA2 = 0;}
#define RSHIGH         RA5=1
#define RSLOW          RA5=0
#define RS_OUTPUT      TRISA5 = 0
#define RWHIGH         RA3=1
#define RWLOW          RA3=0
#define RW_OUTPUT      TRISA3 = 0
#define BUSY_FLAG      RB3
#define DATA_DIR_RD    {TRISB3=1;TRISB2=1;\
                        TRISB1=1;TRISB0=1;}
#define DATA_DIR_WR    {TRISB3=0;TRISB2=0;\
                       TRISB1=0;TRISB0=0;}
#define OUTPUT_DATA(x) {PORTB = x;}

//prototypes
void epulse (void);
void lcd_write(
     unsigned char cmd, unsigned char data_flag, unsigned char chk_busy, unsigned char dflag);
void lcd_init(void);
void putch (char c);
 
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 our single char output function
                             // which will be character output 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(3);   // wait for busy flag to be ready
}

// 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) {   //char function called by _H_USER stream
    putch (c);
}
#endif


void main(void){
  // configure, see control pins as outputs
  // initialize as low
  E_OUTPUT;  RS_OUTPUT;  RW_OUTPUT;
  ELOW; RSLOW;  RWLOW; 
  lcd_init ();
  printf("******Hello, my name is Bob********");
  lcd_write(0xC0,0,1,1);  // cursor to 2nd line
  printf("-----these lines are moving!-------");
  while(1) {
      // shift left
      lcd_write(0x18,0,1,1);  
      DelayMs(100);
      DelayMs(100);
      DelayMs(100);
  }
}