Lesson 30 I2C LCD1602

Introduction

LCD1602 is a character type liquid crystal display, which can display 32 (16*2) characters at the same time. It has 16 pins, of which at least 7 would be used each time. You can use a PCF8574 I2C chip to expand I/O ports so only two GPIO ports would be occupied.

Components

– 1 * Raspberry Pi

– 1 * Breadboard

– 1 * Network cable (or USB wireless network adapter)

– 1 * I2C LCD1602

– Several jumper wires (M to F)

Experimental Principle

In this experiment, I2C is used to configure LCD so that you can control the LCD1602 to display characters. The I2C slave address of I2C LCD1602 here is 0x27.

Experimental Procedures

Step 1: Build the circuit

Raspberry Pi	I2C LCD1602 Module
SCL	SCL
SDA	SDA
5V	VCC
GND	GND

Step 2: Setup I2C (see Appendix 1. If you have set I2C, you can skip this step.)

For C language users:

Step 3: Change directory

 cd /home/pi/SunFounder_SensorKit_for_RPi2/C/30_i2c_lcd1602/

Step 4: Compile

gcc i2c_lcd1602.c -lwiringPi

Step 5: Run

sudo ./a.out

For Python users:

Step 3: Change directory

 cd /home/pi/SunFounder_SensorKit_for_RPi2/Python/

Step 4: Run

sudo python 30_i2c_lcd1602.py

Now you can see “Greetings! From SunFounder” displayed on the LCD.

 C Code

#include <stdio.h>
#include <wiringPi.h>
#include <wiringPiI2C.h>
#include <string.h>

int LCDAddr = 0x27;
int BLEN = 1;
int fd;

void write_word(int data){
	int temp = data;
	if ( BLEN == 1 )
		temp |= 0x08;
	else
		temp &= 0xF7;
	wiringPiI2CWrite(fd, temp);
}

void send_command(int comm){
	int buf;
	// Send bit7-4 firstly
	buf = comm & 0xF0;
	buf |= 0x04;			// RS = 0, RW = 0, EN = 1
	write_word(buf);
	delay(2);
	buf &= 0xFB;			// Make EN = 0
	write_word(buf);

	// Send bit3-0 secondly
	buf = (comm & 0x0F) << 4;
	buf |= 0x04;			// RS = 0, RW = 0, EN = 1
	write_word(buf);
	delay(2);
	buf &= 0xFB;			// Make EN = 0
	write_word(buf);
}

void send_data(int data){
	int buf;
	// Send bit7-4 firstly
	buf = data & 0xF0;
	buf |= 0x05;			// RS = 1, RW = 0, EN = 1
	write_word(buf);
	delay(2);
	buf &= 0xFB;			// Make EN = 0
	write_word(buf);

	// Send bit3-0 secondly
	buf = (data & 0x0F) << 4;
	buf |= 0x05;			// RS = 1, RW = 0, EN = 1
	write_word(buf);
	delay(2);
	buf &= 0xFB;			// Make EN = 0
	write_word(buf);
}

void init(){
	send_command(0x33);	// Must initialize to 8-line mode at first
	delay(5);
	send_command(0x32);	// Then initialize to 4-line mode
	delay(5);
	send_command(0x28);	// 2 Lines & 5*7 dots
	delay(5);
	send_command(0x0C);	// Enable display without cursor
	delay(5);
	send_command(0x01);	// Clear Screen
	wiringPiI2CWrite(fd, 0x08);
}

void clear(){
	send_command(0x01);	//clear Screen
}

void write(int x, int y, char data[]){
	int addr, i;
	int tmp;
	if (x < 0)  x = 0;
	if (x > 15) x = 15;
	if (y < 0)  y = 0;
	if (y > 1)  y = 1;

	// Move cursor
	addr = 0x80 + 0x40 * y + x;
	send_command(addr);
	
	tmp = strlen(data);
	for (i = 0; i < tmp; i++){
		send_data(data[i]);
	}
}


void main(){
	fd = wiringPiI2CSetup(LCDAddr);
	init();
	write(0, 0, "Greetings!");
	write(1, 1, "From SunFounder");
	delay(2000);
	clear();
}

Python Code

#!/usr/bin/env python
import LCD1602
import time

def setup():
	LCD1602.init(0x27, 1)	# init(slave address, background light)
	LCD1602.write(0, 0, 'Greetings!!')
	LCD1602.write(1, 1, 'from SunFounder')
	time.sleep(2)

def loop():
	space = '                '
	greetings = 'Thank you for buying SunFounder Sensor Kit for Raspberry! ^_^'
	greetings = space + greetings
	while True:
		tmp = greetings
		for i in range(0, len(greetings)):
			LCD1602.write(0, 0, tmp)
			tmp = tmp[1:]
			time.sleep(0.8)
			LCD1602.clear()

def destroy():
	pass	

if __name__ == "__main__":
	try:
		setup()
		while True:
			pass
	except KeyboardInterrupt:
		destroy()