“IoT: The Struggle for Meaning” by Massimo Banzi

Massimo Banzi explores the Internet of Things during an Arduino Day 2016 talk in Berkeley, CA.

I2C 4x20 LCD, test on Arduino Uno using LiquidCrystal_I2C library

Test I2C 4x20 LCD on Arduino Uno using LiquidCrystal_I2C library. marcoschwartz/LiquidCrystal_I2C is a LiquidCrystal Arduino library for the DFRobot I2C LCD displays.

- Install LiquidCrystal_I2C library in Arduino Software:

- Open the example of LiquidCrystal_I2C > HelloWorld

//YWROBOT
//Compatible with the Arduino IDE 1.0
//Library version:1.1
#include <Wire.h> 
#include <LiquidCrystal_I2C.h>

LiquidCrystal_I2C lcd(0x27,20,4);  // set the LCD address to 0x27 for a 16 chars and 2 line display

void setup()
{
  lcd.init();                      // initialize the lcd 
  lcd.init();
  // Print a message to the LCD.
  lcd.backlight();
  lcd.setCursor(3,0);
  lcd.print("Hello, world!");
  lcd.setCursor(2,1);
  lcd.print("Ywrobot Arduino!");
   lcd.setCursor(0,2);
  lcd.print("Arduino LCM IIC 2004");
   lcd.setCursor(2,3);
  lcd.print("Power By Ec-yuan!");
}


void loop()
{
}

Test with Arduino Uno:
Uno A4 (SDA) - SDA
Uno A5 (SCL) - SCL
Uno +5V - VCC
Uno GND - GND

Remark:
- It's a jumper on the daughter board on the back side, it have to be insert (short) to turn on the back light.
- Most probably you have to adjust the potentiometer on the daughter board to make the LCD characters clear.
- The I2C address of the board is 0x27, you can check it with i2cdetect library.

i2cdetect library - Arduino library to I2C bus for devices.

mcauser/i2cdetect is a Arduino library for scanning I2C bus for devices. Outputs a table similar to the linux program (i2cdetect - detect I2C chips) of the same name.

- Add i2cdetect library:
Open Library Manager (Sketch > Include Library > Manager Libraries...) to install i2cdetect library

- Open i2cdetect example (File > Examples > i2cdetect > i2cdetect)

i2cdetect.ino

#include <Wire.h>
#include <i2cdetect.h>

void setup() {
  Wire.begin();
  Serial.begin(9600);
  Serial.println("i2cdetect example\n");
  Serial.print("Scanning address range 0x03-0x77\n\n");
}

void loop() {
  i2cdetect();  // default range from 0x03 to 0x77
  delay(2000);
}

Output example to shown a I2C device with address 0x27 is connected.
- Run on Arduino Uno
- A4 (SDA), A5 (SCL)