// Aubrey Simonson
// asimonso@mit.edu
// How to Make (almost) Anything
// December 16th, 2019
//
// (c) Aubrey Simonson 2019
// This work may be reproduced, modified, distributed,
// performed, and displayed for any purpose. Copyright is
// retained and must be preserved. The work is provided
// as is; no warranty is provided, and users accept all
// liability.
//
//
//Adapted from Ivan Sanchez
//link to original: http://fab.academany.org/2018/labs/fablaboulu/students/heidi-hartikainen/W9.html
//You made PA2 and PA3 always be on.  PB2 will be turned on if power is supplied to PA7
//
#ifndef F_CPU
#define F_CPU 20000000UL // 20 MHz clock speed
#endif

//these two lines taken from hello echo board
#define serial_port PORTA
#define serial_pin_out (1 << PA1)//this may actually be PA0.  test that if it doesn't work.


#include <avr/io.h> //Library to handle avr inputs and outputs
#include <util/delay.h> // Library to add delays. Necessary for blinking.

//mysterious helper function taken from hello echo board
void put_string(volatile unsigned char *port, unsigned char pin, char *str) {
   //
   // print a null-terminated string
   //
   static int index;
   index = 0;
   do {
      put_char(port, pin, str[index]);
      ++index;
      } while (str[index] != 0);
   }


int main(void)
{
  // DDRB Port B Data Direction Register. Selects direction of pins.
  //This sets pins PB2, PA3, PA2, and PA7 as inputs
	DDRB = DDRB | (1 << PB2);
	DDRA = DDRA | (1 << PA3);
	DDRA = DDRA | (1 << PA2);
	DDRA = DDRA | (1 << PA7);

  //this is how we will record which pins are high and which are low.
  //each digit coresponds to a pad on the sensor.
  //yes, in c, a string isn't a string, it's an array of characters.
  //which it is in most languages, technically, but you never have to interact with
  //a string as a char array in the same way that in the real world we never have to
  //engage with individual atoms god why is c like this.
	char cube_reading[] = {'0', '0', '0', '0'};
	while (1)
	{
		//for each of our 4 pins, check if they are high or low.
    //if they are high, set the corresponding character of cube_reading to 1.
    //if they are low, set the corresponding character of cube_reading to 0.
    uint8_t val = PINB & (1 << PB2);
    if(!val){
      cube_reading[0] = '1';
    }
    else {
      cube_reading[0] = '0';
    }
    uint8_t val = PINA & (1 << PA3);
		if(!val){
      cube_reading[1] = '1';
		}
    else {
      cube_reading[1] = '0';
    }
    uint8_t val = PINA & (1 << PA2);
		if(!val){
      cube_reading[2] = '1';
		}
    else {
      cube_reading[2] = '0';
    }
		uint8_t val = PINA & (1 << PA7);
		if(!val){
      cube_reading[3] = '1';
		}
		else {
			cube_reading[3] = '0';
		}
    //communicate cube_reading to another device
    put_string(&serial_port, serial_pin_out, "cube reader: " + cube_reading);
	}
}