/*
 * Cruz_Ivan_Lab3.c
 *
 * Created: 2/17/2020 2:11:00 PM
 * Author : Ivan Cruz
 */

#include <avr/io.h>
#define F_CPU 16000000UL
#define BAUD 9600 // define baud
#define BAUDRATE ((F_CPU)/(BAUD*16UL)-1) // set UBRR value for baud rate
#include <util/delay.h>

void uart_init (void)
{
	UBRR0H = (BAUDRATE>>8); // shift the register right by 8 bits
	UBRR0L = BAUDRATE; // set baud rate
	UCSR0B|= (1<<TXEN0)|(1<<RXEN0); // enable receiver and transmitter
	UCSR0C|= (1<<UCSZ00)|(1<<UCSZ01); // 8bit data format
}


void uart_transmit (unsigned char data) {
	while (!( UCSR0A & (1<<UDRE0))); // wait while register is free
	UDR0 = data; // load data in the register
}

unsigned char uart_recieve (void)
{
	while(!((UCSR0A) & (1<<RXC0))); // wait while data is being received
	return UDR0; // return 8-bit data
}
// function to initialize UART

int main()
{
	char keypad[4][4] = {{'1', '2', '3', 'A'}, //4x4 keypad layout
						 {'4', '5', '6', 'B'}, //based on the
						 {'7', '8', '9', 'C'}, //tools given to us
						 {'*', '0', '#', 'D'}};  // for lab

	uart_init();
	DDRD |= (1<<DDD4 | 1<<DDD5 | 1<<DDD6 | 1<<DDD7); // ddrd = output
	DDRB &= ~(1<<DDB0 | 1<<DDB1 | 1<<DDB2 | 1<<DDB3); //ddrb = input
	PORTB |= (1<<PORTB0) | (1<<PORTB1) | (1<<PORTB2) | (1<<PORTB3); // enables pull up

	while(1)
	{
			for(int i = 7; i>=4 ; i--){
				PORTD |= (1<<4|1<<5|1<<6|1<<7);
				PORTD &= ~(1<<i);

				for(int j =0; i<=3; j++){
					if(!(PINB & 1<<j)){
						uart_transmit(keypad[i-4][j]);
						_delay_ms(500);
						}
				}
			}
	}
}