Data Memory

/*
 * data memory.cpp
 *
 * Created: 8/27/2022 10:30:16 AM
 * Author : Sumaiya Sultana
 */ 

#define F_CPU 1000000UL
#include <avr/io.h>
#include <avr/interrupt.h>
#include <util/delay.h>

#define CLK_		0x04
#define RESET_		0x08
#define MEM_READ_	0x02
#define MEM_WRITE_	0x01

uint8_t MEMORY[1<<4];
uint8_t destination;
uint8_t writeData;
uint8_t data_out;
uint8_t signal;

void memory_reset() {
	for (int i=0; i<16; i++)
	MEMORY[i] = 0;
}

ISR(INT0_vect)
{
	if(signal & MEM_WRITE_){
		MEMORY[destination] = writeData;
	}
	_delay_ms(50);
}

/*
										-U-
	mem addrs 0			|	1			A0	40	|	Memory Write Signal
	mem addrs 1			|	2				39	|	Memory Read Signal
	mem addrs 2			|	3				38	|	Clock Signal //this pin may remain unused, give clk connection in D2
	mem addrs 3			|	4				37	|	Reset Signal	
write data 4			|	5				36	|				
write data 5			|	6	B		A	35	|				
write data 6			|	7				34	|				
write data 7			|	8				33	|			
		!reset			|	9				32	|		AREF		
				VCC		|	10				31	|		GND		
				GND		|	11				30	|		AVCC		
						|	12			C7	29	|		
						|	13				28	|		
						|	14	D0			27	|		
						|	15				26	|		
					CLK	|	16	D2			25	|		data out 3
						|	17				24	|		data out 2
						|	18				23	|		data out 1
						|	19			C0	22	|		data out 0
						|	20			D7	21	|				
*/


int main(void)
{
	// Some pins of PORTC can not be used for I/O directly.
	// turn of JTAG to use them
	// o write a 1 to the JTD bit twice consecutively to turn it off
	MCUCSR = (1<<JTD);  MCUCSR = (1<<JTD);
	
	DDRA = 0xF0;	// A[0] - Memory Write | A[1] - Memory Read | A[2] - Clock | A[3] - Reset
	PORTA = 0X04;	//to set clock high
	DDRB = 0x00;	// Address B[3:0] | Write Data B[7:4]
	
	DDRC = 0xFF;	// C[3:0] - Data Read
	
	GICR = 1<<INT0;		/* Enable INT0*/
	MCUCR = 1<<ISC01;   /* Trigger INT0 on falling edge */
	MCUCR &= (~(1<<ISC00));
	
	memory_reset();
	sei();
	while (1)
	{
		destination = PINB; //addrss in lsb, write data in msb
		writeData = (destination & 0xF0)>>4;
		destination &= 0x0F;
		signal = PINA;
		signal &= 0x0F;
		if (signal & RESET_) {
			memory_reset();
			_delay_ms(100);
		}
		if (signal & MEM_READ_) {
			PORTC = MEMORY[destination];
			_delay_ms(50);
		}
	}
	
}