The AVR microcontroller boards which are provided with all the basic circuitry for the operation of the microcontroller which has been flashed with the Arduino boot-loader are called Arduino boards. The Arduino can communicate with the other devices using its digital I/O, serial port, I2C port, SPI port etc. The Arduino IDE is so simple to use that anyone who has basic knowledge of c programming can quickly get started with it. The tutorial on Getting started with Arduino explains about the steps required to get start with an Arduino board.The Arduino board used in this project is the Arduino pro-mini board and the IDE version of the Arduino is 1.0.3 for windows. The image of the Arduino pro-mini board and the Arduino IDE are shown below;
Fig. 2: Typical Arduino Pro-Mini Board
Fig. 3: Arduino IDE Software Window
Since the Arduino pro-mini board has no circuitary for interfacing it with the serial port or the USB port of the PC, an external USB to TTL converter board is required to connect it with the PC. This hardware helps in programming the Arduino board and also helps in the serial communication with the USB port of the PC.
Fig. 4: External USB to TTL converter board for programming Arduino and serial communication
It is assumed that the reader has gone through the project how to get started with the Arduino and tried out all the things discussed there.
This project uses function for accessing LCD module available from the library <LiquidCrystal.h> as explained in the previous project on how to interface the 4 bit LCD with Arduino board. The serial communication functions are also used in this project which is already discussed in a previous project on how to receive and send serial data using Arduino.
Apart from those functions this project make use of two more functions for the LCD namely lcd.write() and lcd.autoscroll() the details of them are discussed in the following section.
Thelcd.write() also a function which is used to print the data to the LCD screen like the lcd.print() function does. Unlike the lcd.print() function the lcd.write() function directly write the value to the LCD screen without formatting it as ASCII. This function is analogues to the Serial.write() function discussed in the project how to receive and send serial data using Arduino.
This function is called after initializing the LCD module using the lcd.begin() function and after setting the cursor position using the lcd.setCursor() function. This function make the scrolling possible by shifting the current displayed data to either side of the LCD as each characters are written into the LCD screen.
The code initializes the LCD library as per the connection of the LCD with the Arduino board using the function LiquidCrystallcd(). The function lcd.begin() is used to initialize the LCD module in four bit mode with two line display. The lcd.setCursor() function is used to set the cursor at the 16th position of the second line of the 16*2 LCD from where the scrolling is supposed to start.
The serial port is initialized with 9600 baud rate using the function Serial.begin(). The function Serial.available() is used in the code to check whether a serial data is available to read or not.
The Serial.read() function is used to read the serial data coming from the PC which is then stored to a variable and is displayed on the LCD using the function lcd.write().
// include the library code:
// initialize the library with the numbers of the interface pins
LiquidCrystallcd(12, 11, 5, 4, 3, 2);
// give the pin a name:
int led = 6;
// incoming byte
// initialize the led pin as an output.
// set up the LCD’s number of columns and rows:
// initialize the serial communications:
// set the cursor to (16,1):
// set the display to automatically scroll:
// if we get a valid byte, read analog ins:
// get incoming byte:
inByte = Serial.read();
// send the same character to the LCD
// glow the LED
Whenever a key is pressed in the keyboard the code receives the data byte and sends the same byte to display it in the LCD screen after shifting the current display to one side. The code also blinks an LED each time it transmits a data to the serial port using the functions pinMode (), digitalWrite () and delay (). The details of those functions are already discussed in the previous project on How to use digital input and digital output of the Arduino board. Once the coding is finished one can verify and upload the code to the Arduino board as explained in the project how to get started with the Arduino.