Question

This code listens to keypresses and displays the ASCII code of the key pressed on the LEDs. Port A needs to be connected to the keypad and port D needs to be connected to the LED port.

I need you Modify the code such that the array is cleared when the ‘*’ key is pressed and an LED is turned on when the ‘#’ key is pressed.

#include <avr/io.h>
#define F_CPU 8000000UL
#include <util/delay.h> // Delay header
#define KEY_PRT PORTA //Keyboard port, DDR, PIN
#define KEY_DDR DDRA
#define KEY_PIN PINA
unsigned char keypad[4][3] = {{'1','2','3'},
{'4','5','6'},
{'7','8','9'},
{'*','0','#'}};
int main ()
{
   unsigned char colloc, rowloc;
   DDRD = 0xFF;
   KEY_DDR = 0xFF;
   KEY_PRT = 0x0F;
   while(1)
   {
       while(1)
       {
           KEY_DDR = 0xF0;
           KEY_PRT = 0xFF;
           do
           {
               KEY_PRT &= 0x0F; //Ground all columns
               asm("NOP");
               rowloc = (KEY_PIN & 0x0F); //read all rows
           }while(rowloc != 0x0F); //check until all keys are released
           do
           {
               //PORTD = 0b00000100;
               do
               {
                   //PORTD = 0b00001000;
                   _delay_ms(20);
                   rowloc = (KEY_PIN & 0x0F); //see if any key is pressed
               }while(rowloc == 0x0F);//keep checking for key press
               _delay_ms (20); //delay for debounce
               rowloc = (KEY_PIN & 0x0F); //read rows
           }while(rowloc == 0x0F); //wait for key press
           KEY_PRT = 0x3F; //ground column 0
           asm("NOP");
           rowloc = (KEY_PIN & 0x0F); //read the rows
          
           if(rowloc != 0x0F) //column detected
           {
               colloc = 0; //save column location
               break; // exit while loop
           }
           KEY_PRT = 0x5F; // ground column 1
           asm("NOP");
           rowloc = (KEY_PIN & 0x0F); //read the rows
           if(rowloc != 0x0F)
           {
               colloc = 1; //save column location
               break;
           }
           KEY_PRT = 0x6F; // ground column 2
           asm("NOP");
           rowloc = (KEY_PIN & 0x0F);
           if(rowloc != 0x0F) //read the rows
           {
               colloc = 2; //save column location
               break;
           }
       }
       //Check row and send result to port D
       if(rowloc == 0x0E)
       PORTD = keypad[0][colloc];
       else
       if(rowloc == 0x0D)
       PORTD = keypad[1][colloc];
       else
       if(rowloc == 0x0B)
       PORTD = keypad[2][colloc];
       else
       PORTD = keypad[3][colloc];
   }
   return 0;
}

Answer 1

1)For clearing array:

It will be efficient to first convert the array to vector and use the clear() function.

Code for this part:

// converting array to vector.

#include iostream

#include vector

int main(){

std::vector<int> V;

V.insert(V.begin(),std::begin(keypad),std::end(keypad));

for(int j:V){std::cout<<i<<“”;}return 0;}

//for erasing the contents of vector.

V.clear();

2)For the LED on:

int pin=13;

void process()

{pinmode(pin,OUTPUT);}

void process2(){

digitalWrite(pin,HIGH);

delay(800);

digitalWrite(pin,LOW);

delay(800);

}