declare pin 9 to be an output: pinMode(9, OUTPUT) initialize the library with the numbers of the interface pins LiquidCrystal lcd(12, 11, 5, 4, 3, 2) but with modifications to the LCD contrast to make itĪdjustable via software The circuit: * LCD RS pin to digital pin 12 * LCD Enable pin to digital pin 11 * LCD R/W pin to Ground * LCD VO pin (pin 3) to PWM pin 9 * LCD D4 pin to digital pin 5 * LCD D5 pin to digital pin 4 * LCD D6 pin to digital pin 3 * LCD D7 pin to digital pin 2 */ // include the library code: This sketch is based on the Arduino sample sketch at This sketch prints "Hobbytronics" to the LCD and shows the time. The LiquidCrystal library works with all LCD displays that are compatible with the Hitachi HD44780 driver. There are many of them out there, and you can usually tell them by the 16-pin interface. * LiquidCrystal Library - Hobbytronics Demonstrates the use a 16x2 LCD display. The PWM output to control the contrast is done in the setup routine, however, if you wanted to be able to control the contrast manually, then the addition of two push buttons and a bit more coding would allow you to increase and decrease the contrast in simple steps within the program. Here are the pinouts from the LCD and the corresponding pin connection on the Arduinoīelow is a mockup of the wiring connections and the output displayed on the screenĪnd here is the Arduino Sketch. You may want to increase or decrease this figure to get the correct contrast on your LCD screen. We have set the PWM output initially to 50 (output is ON about 20% of the time) to give a value approximating 1V. A voltage of approx 0.5V to 1V is about right, but depends on the ambient temperature. The lower the voltage the higher the contrast and vice versa. The contrast pin on the LCD requires a fairly small voltage for ideal display conditions. A 100uF capacitor is connected between the PWM output and ground. Pin 9 is used as the PWM output and this connects to the Vo contrast pin on the LCD (pin 3). Instead we will use one of the Arduino PWM outputs, smoothed by a capacitor, to create a simple Digital to Analog output which will allow us to control the screen contrast digitally from within our program. Just to be different, we will make a small enhancement and do away with the Potentiometer that is normally required to adjust the screen contrast. We will use a similar LCD (Pololu 16x2 Character LCD 773 or 772) The Arduino IDE comes with an example LCD sketch which uses an Hitachi HD44780 compatible LCD. Lcd.We are now going to add an LCD display to our Arduino. lcd.begin(cols, rows) cols: the number of columns in LCD rows: the number of rows in LCD lcd.begin() needs to be called before any other LCD library commands. Initializes the interface to the LCD screen, and specifies the dimensions (width and height) of the display. Now d0, d1, d2, and d3 are optional if omitted, the LCD will be controlled using only the four data lines (d4, d5, d6, d7)and RS, E control line. The RW pin tied to ground instead of connected to a pin on the Arduino. If we are using function LiquidCrystal(rs, enable, d4, d5, d6, d7) then we need only 6 arduino pins. The display can be controlled using 4 or 8 data lines. Here transistor works as a switch and by applying a high signal to its base triggers the buzzer to beep. We are connecting the buzzer to the Vcc and collector of the transistor BC548. LCD Screen (compatible with Hitachi HD44780 driver).LiquidCrystal(rs, rw, enable, d0, d1, d2, d3, d4, d5, d6, d7) įrom the above table you can use any function to drive the LCD but we are using the first function because it uses only 6-I/O pins. LiquidCrystal(rs, rw, enable, d4, d5, d6, d7) LiquidCrystal(rs, enable, d4, d5, d6, d7) LiquidCrystal() function and I/O required # We can use any combination of connection from arduino uno to 16×2 LCD. If we are not using the pin D0 to D3 and RW. As LCD can be controlled from 4 or 8-bit data lines.
Let’s understand the LCD functions and its connections.