Embedded Systems

/* Keypad and LEDs

Circuit Connections:
**LEDs
               PIN_0 => LED1_Anode - LED1_Cathode = > Resistor 150Ω => Gnd
               PIN_1 => LED2_Anode - LED2_Cathode = > Resistor 150Ω => Gnd
               PIN_2 => LED3_Anode - LED3_Cathode = > Resistor 150Ω => Gnd             
               PIN_3 => LED4_Anode - LED4_Cathode = > Resistor 150Ω => Gnd
               PIN_4 => LED5_Anode - LED5_Cathode = > Resistor 150Ω => Gnd
**Keypad
               PIN_5 => Column4
               PIN_6 => Column3
               PIN_7 => Column2
               PIN_8 => Column1
               PIN_9 => Row4
               PIN_10 => Row3
               PIN_11 => Row2
               PIN_12 => Row1
*/

//inlcude the library
#include <Keypad.h>
#define led1 0                   //give the name "led1" to PIN_0
#define led2 1                   //give the name "led2" to PIN_2
#define led3 2                   //give the name "led3" to PIN_2
#define led4 3                   //give the name "led4" to PIN_3
#define led5 4                   //give the name "led5" to PIN_4
const byte cols = 4; //four columns
const byte rows = 4; //four rows

//keypad output
char keys[rows][cols] = {
  {'1','2','3','A'},
  {'4','5','6','B'},
  {'7','8','9','C'},
  {'*','0','#','D'}
};

//configure the Arduino Uno - Keypad interface
byte row_pins[] = {12,11,10,9}; //pins connect to the rows
byte col_pins[] = {8, 7, 6, 5}; //pins connect to the columns
Keypad keypad = Keypad(makeKeymap(keys), row_pins, col_pins, rows, cols);

//variable to save keypad's charachters
char key;

//The setup() function initializes and sets the initial values
//It will only run once after each power up or reset
void setup(){
//Configure the PIN_0, PIN_1, PIN_2, PIN_3, PIN_4
//to behave as output
pinMode(led1, OUTPUT);
pinMode(led2, OUTPUT);
pinMode(led3, OUTPUT);
pinMode(led4, OUTPUT);
pinMode(led5, OUTPUT);
}

//loops consecutively
void loop(){
//get a key from keypad
key = keypad.getKey();
//check if a key is pressed
if (key != NO_KEY){
   //call the function "set_leds" 
   set_leds(key);
  }
}

//this function configures the LEDs 
//according to the key pressed
void set_leds(char x){
if(x=='0'){ //all LEDs are OFF
   digitalWrite(led1, LOW);
   digitalWrite(led2, LOW);
   digitalWrite(led3, LOW);
   digitalWrite(led4, LOW);
   digitalWrite(led5, LOW);
   }
else if(x=='1'){ //LED1 is ON
   digitalWrite(led1, HIGH);
   digitalWrite(led2, LOW);
   digitalWrite(led3, LOW);
   digitalWrite(led4, LOW);  
   digitalWrite(led5, LOW);
   }
else if(x=='2'){ //LED2 is ON
   digitalWrite(led1, LOW);
   digitalWrite(led2, HIGH);
   digitalWrite(led3, LOW);
   digitalWrite(led4, LOW);
   digitalWrite(led5, LOW);
   }
else if(x=='3'){ //LED3 is ON
   digitalWrite(led1, LOW);
   digitalWrite(led2, LOW);
   digitalWrite(led3, HIGH);
   digitalWrite(led4, LOW);
   digitalWrite(led5, LOW);
   }
else if(x=='4'){ //LED4 is ON
   digitalWrite(led1, LOW);
   digitalWrite(led2, LOW);
   digitalWrite(led3, LOW);
   digitalWrite(led4, HIGH);
   digitalWrite(led5, LOW);
   }
else if(x=='5'){ //LED5 is ON
   digitalWrite(led1, LOW);
   digitalWrite(led2, LOW);
   digitalWrite(led3, LOW);
   digitalWrite(led4, LOW);
   digitalWrite(led5, HIGH);
   }
else{ //all LEDs are ON
   digitalWrite(led1, HIGH);
   digitalWrite(led2, HIGH);
   digitalWrite(led3, HIGH);
   digitalWrite(led4, HIGH);
   digitalWrite(led5, HIGH);
   }
}