Embedded Systems

/* Voltmeter
Circuit Connections:
** LCD
               Ground                    => Gnd
               Power                     => Vcc
               Contrast                  => Potentiometer
               RS                        => PIN_0
               RW                        => Gnd
               E                         => PIN_1
               DB0                       => Gnd
               DB1                       => Gnd
               DB2                       => Gnd
               DB3                       => Gnd
               DB4                       => PIN_2
               DB5                       => PIN_3
               DB6                       => PIN_4
               DB7                       => PIN_5
               LED Anode                 => Vcc
               LED Cathode               => Resistor 220Ω => Gnd
** Potentiometer 1
               Terminal 1                => Gnd
               Wiper                     => LCD_Contrast
               Terminal 2                => Vcc
** Potentiometer 2
               Terminal 1                => Gnd
               Wiper                     => PIN_A0
               Terminal 2                => Vcc
*/
//include the library
#include <LiquidCrystal.h>
#define RS 0              //give the name "RS" to PIN_0
#define EN 1              //give the name "EN" to PIN_1
#define DB4 2             //give the name "DB4" to PIN_2
#define DB5 3             //give the name "DB5" to PIN_3
#define DB6 4             //give the name "DB6" to PIN_4
#define DB7 5             //give the name "DB7" to PIN_5
#define pot_pin A0        //give the name "pot_pin" to PIN_A0

//configure the library with Arduino Uno - LCD interface
LiquidCrystal lcd(RS, EN, DB4, DB5, DB6, DB7);


//variableto save data from ADC
int adc_value; //number range 0~1023
//variable to calculate the analog voltage
float voltage;

//The setup() function initializes and sets the initial values
//It will only run once after each powerup or reset
void setup() {
//configure the LCD's columns and rows
lcd.begin(16, 2);
//print a message
lcd.print("The voltage is");
}

//This function loops consecutively
void loop() {
//read value form ADC
adc_value = analogRead(pot_pin);
//calculate the analog voltage
voltage=(float)adc_value*5/1024;
//go to: first column, second row
lcd.setCursor(0,1);
//print a message
lcd.print(voltage);
lcd.print(" Volt");
//wait for 0.5s
delay(500);
}