Display "Hello World" on 16x2 LCD Using Swift Language

If you want to show the messages or display data, the LCD is a great choice. You could find various LCDs. In this mission, you will look at a 16x2 character LCD. Let's display the phrase "Hello World" on it.

The parts you will need are all included in this Maker kit.

• SwiftIO board
• Shield
• 16x2 LCD
• 4-pin cable

This kind of LCD has 16 columns and 2 rows. So it could display 32 characters. Each character consists of 5 columns and 8 rows, that is, 40 pixels.

In its coordinate system, the upper left corner is the origin (0,0). Its coordinate system is as above.

This LCD supports I2C communication. All the commands to control it are in its data sheet. But you don't need to worry about it. You could find the file LCD1602.swift in your project. It has done the work for you, you could directly use the methods to control your LCD.

Inter-integrated circuit, I2C (I two C or I squared C) for short, is a protocol suitable for short-distance communication. It allows multiple slave devices to communicate with one master device using merely two wires, which constitutes its huge advantage compared to other protocols.

For the communication protocols, there are always master and slave devices. Master device controls the communication process. Slave devices would respond to the master device when it’s called. In our project, the SwiftIO board is always the master, and the other devices serve as slaves.

The two wires contain an SCL and an SDA line:

• SCL (serial clock) carries the clock signal generated by the master. With a preset speed, the devices know the time to transmit each bit and could predict if the data transmission is completed. Thus, it could ensure synchronous data transmission between devices.
• SDA (serial data) is the data line. All the data is transferred on this line by master or slave devices. And the data is usually in bytes. Each communication protocol specifies its own system about how the data is sent. We'll not talk much about it here.

Why could only two wires support multiple devices without confusion? This is because each I2C device has its unique address. You could always find it in its datasheet. At the beginning of the communication, the master will send the address of the device that is wanted. Only the corresponding device would respond and prepare for the following process. Thus there won’t be confusion among different devices.

In brief, if you want to communicate with some devices, you need to find the corresponding data of the command in the datasheet, then send the data according to the rules of communication protocol.

Place the shield on top of the SwiftIO board.

Connect the LCD to the pins I2C0. You could see there are three available I2C0. You could choose any of them.

// Import the SwiftIO library to use everything in it.
import SwiftIO

// Import the board library to use the Id of the specific board.
import SwiftIOBoard

// Initialize the I2C0 and the lcd.
let i2c = I2C(Id.I2C0)
let lcd = LCD1602(i2c)

// Set the display area and print the message on the LCD.
lcd.write(x: 0, y: 0, "Hello World!")

while true {

}

The file LCD1602.swift has configured the LCD according to its datasheet. It is included in the project, so you could directly use these methods to control your LCD

Let's look at the file main.swift.

import SwiftIO
import SwiftIOBoard

Import the necessary libraries: SwiftIO and SwiftIOBoard. SwiftIO is used to control the input and output of the SwiftIO board. SwiftIOBoard defines the pin name of the board.

let i2c = I2C(Id.I2C0)
let lcd = LCD1602(i2c)

Initialize the I2C interface. To initialize the LCD, you need to tell the I2C interface, the other parameters already have a default value.

lcd.write(x: 0, y: 0, "Hello World!") 

Then you will use the method write(x:y:_:) to display the string. It has three parameters. At first, you need to set the coordinate of the start point. Here you start from the origin (0,0). The third parameter is the content you would like to display. It is a string. So you add the content within the double quotation marks.

Since the text would always display on the LCD, you could write it above the loop. Even there is nothing on the loop, you need to add it to your code.

After you download the code, the screen displays the words "Hello World!".