PIC16F887 MCP23017 LCD and Keypad Interfacing using XC8

In previous post, I use the MCP23017 16-bit I/O expander chip to interface with LED and DIP switch, 4x4 matrix keypad, and the HD44780 based character LCD. Here I will put them altogether using a 4x4 matrix keypad and a 16x2 character LCD.

Program Start Up

In this example, the micro-processor keep tracks of keypad scanning. When the a key-press is detected it will send to a 16x2 character LCD via the MCP23017 I2C communication interface. The LCD is automatically create new line and return home by software.

/*
 * File:   main.c
 * Author: Admin
 *
 * Created on January 22, 2024, 9:04 AM
 */
 
#include <xc.h>
#include "config.h"
#include "mcp23017.h"
 
#define _XTAL_FREQ  8000000
 
void main(void) {
    OSCCONbits.IRCF=7;
    __delay_ms(100);
    lcd_init();
    __delay_ms(100);
    lcd_text("  MCP23017 I2C");
    lcd_xy(1,2);
    lcd_text("  LCD Key Pad");
    __delay_ms(3000);
    lcd_clear();
    uint8_t temp,counter=0,new_line=0,line_num=1;
    while(1){
        temp=keyScan();
        if(temp!=0xFF){
            lcd_data(temp);
            counter++;
            __delay_ms(250);
        }
        if(counter>=16) {counter=0; new_line=1;}
        if(new_line){
            new_line=0;
            line_num++;
            if(line_num==2) lcd_xy(1,2);
            if(line_num==3){lcd_clear(); line_num=1;}
        }
    }
    return;
}
 

The PIC16F887 use the I2C clock frequency of 400kHz without disruption. Program simulation in Proteus doesn't run smoothly. So I need to test this firmware on a prototype board next.

Keypad Scanning and LCD Display Tasks

Click here to download this example package from GitHub.