//
// Jeffery Durand

// DC_motor.c: listens through 2 by 2 header for signals 
// telling the motor to go forward or backward. 
// The following code puts these signals into action

//
// Used parts of Neil Gershenfeld's code
//

#include <avr/io.h> // basic library
#include <util/delay.h> /* Functions to waste time */
#include <stdbool.h> // contains the booleans

// Certain functions are the same in fact but conceptually different hance the different names
// pin x is always one bit shifted x times
// DDRx manipulation
#define output(directions,pin) (directions |= pin) // set port direction for output (make 1)
#define input(directions,pin) (directions &= (~pin)) // set port direction for input, default (make 0)
// PORTx manipulation
#define set(port,pin) (port |= pin) // set port pin
#define clear(port,pin) (port &= (~pin)) // clear port pin
#define all_set(port) (port = 0xff) // set all port pins, not recommended as different names may be given to same port
#define all_clear(port) (port = 0x00) // clear all port pins
// PINx reading
#define pin_test(pins,pin) (pins & pin) // test for port pin
#define bit_test(byte,bit) (byte & (1 << bit)) // test for bit set

// PROGRAM SPECIFIC
// variables
#define on_delay() _delay_ms(1) // PWM on time
#define power_levels 15 // different levels of power


// COMPONENTS
// H-bridge output
#define bridge_port PORTB // H-bridge port
#define bridge_direction DDRB // H-bridge direction
#define OUT1 (1 << PB3) // OUT1
#define OUT2 (1 << PB4) // OUT2

// external input
#define instruct_port PORTB
#define instruct_direction DDRB
#define instruct_pins PINB
#define IN1 (1 << PB0)
#define IN2 (1 << PB2)



int main(void) {
   
   static uint8_t delay = 0; // delay where the motor is inactive
   static uint8_t count_delay = 0; // variable for loop iteration

   //
   // set clock divider to /1
   //
   CLKPR = (1 << CLKPCE);
   CLKPR = (0 << CLKPS3) | (0 << CLKPS2) | (0 << CLKPS1) | (0 << CLKPS0);
   
   //
   // initialize H-bridge pins
   //
   clear(bridge_port, OUT1);
   output(bridge_direction, OUT1);
   clear(bridge_port, OUT2);
   output(bridge_direction, OUT2);
   
   //
   // initialize pins listening for instuctions
   //
   clear(instruct_port, IN1); // do not need pull up resistors for the connection should be constant
   input(instruct_direction, IN1);
   clear(instruct_port, IN2);
   input(instruct_direction, IN2);

   //
   // main loop
   //
   while (1) {

      // active input pin 1 only: turn forward!
      if (pin_test (instruct_pins, IN1) != 0 && pin_test (instruct_pins, IN2) == 0){
         
         clear(bridge_port, OUT2); // set direction 
         set(bridge_port, OUT1); // make go forward
      }

      // active input pin 2 only: turn backward!
      if (pin_test (instruct_pins, IN1) == 0 && pin_test (instruct_pins, IN2) != 0){
         
         clear(bridge_port, OUT1); // set direction 
         set(bridge_port, OUT2); // make go forward
      }

      // nothing instructed: turn off
      if (pin_test (instruct_pins, IN1) == 0 && pin_test (instruct_pins, IN2) == 0){
         
         clear(bridge_port, OUT1); 
         clear(bridge_port, OUT2); 
      }

      // both turned on (should not happen): ignore and turn off
      if (pin_test (instruct_pins, IN1) != 0 && pin_test (instruct_pins, IN2) != 0){
         
         clear(bridge_port, OUT1); 
         clear(bridge_port, OUT2); 
      }

   }
   return 0;
}