Johnny Five, how to work with an LCD Screen

Apr 28, 2021

Learn how to wire and control a 1602A LCD screen with Johnny Five and Node.js, initializing the LCD class and showing text with the print() method.

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This post is part of the Johnny Five series. See the first post here.

An LCD screen is a pretty cool component because we can use it for many different projects in creative ways.

1602A LCD screen component with dark display and 16 pins along the top edge

This one I have is named 1602A.

Back side of 1602A LCD showing circuit board with labeled pins and components

It has 16 pins. I wired it in this way:

Complete wiring setup with Arduino connected to LCD screen and potentiometer on breadboard

Pin 1 goes to 0V
Pin 2 goes to a potentiometer that controls the backlight
Pin 3 is connected to 5V
Pin 4 goes to Pin 7 on the Arduino
Pin 5 goes to 0V
Pin 6 goes to Pin 8 on the Arduino
Pin 11 goes to Pin 9 on the Arduino
Pin 12 goes to Pin 10 on the Arduino
Pin 13 goes to Pin 11 on the Arduino
Pin 14 goes to Pin 12 on the Arduino
Pin 15 goes to 5V
Pin 16 goes to 0V

Close-up view of LCD connected to breadboard with colorful jumper wires

The potentiometer has 3 pins. The middle one is connected to the LCD screen, the left one is 0V and the right one 5V:

Potentiometer component with three pins wired on breadboard for LCD backlight control

Arduino Uno board connected to LCD project with jumper wires and USB cable

That’s it for the wiring.

Create a new lcd.js file and load this code:

const { Board, LCD } = require("johnny-five")
const board = new Board()

board.on("ready", function () {})

Now initialize a new LCD object from the LCD class.

The exact initialization procedure depends on the kind of display used. In my case, it was this:

const lcd = new LCD({ pins: [7, 8, 9, 10, 11, 12] })

Finally, call the print() method to display a string:

const { Board, LCD } = require("johnny-five")
const board = new Board()

board.on("ready", function () {
  const lcd = new LCD({ pins: [7, 8, 9, 10, 11, 12] })
  lcd.print("Hello World!")
})

and run the program using node lcd.js to see it work:

LCD screen displaying Hello World text in bright blue characters on dark background

The LCD class also offers those cool methods:

clear() to clear the screen
cursor() to position the cursor at a specific place
off() to disable the display
on() to enable the display
blink() to blink the cursor
noBlink() to un-blink the cursor
autoscroll() to turn on automatic scrolling when the message goes too long

You can find out more on http://johnny-five.io/api/lcd/.

Tagged: JavaScript · All topics

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