//
//
// hello.H-bridge.44.DC.c
//
// H-bridge DC motor hello-world
//
// Neil Gershenfeld
// 11/18/12
//
// (c) Massachusetts Institute of Technology 2012
// 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.
//

#include <avr/io.h>
#include <util/delay.h>

#define output(directions,pin) (directions |= pin) // set port direction for output
#define input(directions,pin) (directions &= (~pin)) // set port direction for input
#define set(port,pin) (port |= pin) // set port pin
#define clear(port,pin) (port &= (~pin)) // clear port pin
#define pin_test(pins,pin) (pins & pin) // test for port pin
#define bit_test(byte,bit) (byte & (1 << bit)) // test for bit set
#define bit_delay_time 102 // bit delay for 9600 with overhead
#define bit_delay() _delay_us(bit_delay_time) // RS232 bit delay
#define half_bit_delay() _delay_us(bit_delay_time/2) // RS232 half bit delay
#define char_delay() _delay_ms(10) // char delay
#define led_delay() _delay_ms(100) // LED flash delay
#define long_delay() _delay_ms(500) // error flash delay

#define serial_port PORTB
#define serial_pins PINB
#define serial_direction DDRB
#define serial_pin_in (1 << PB0)
#define serial_pin_out (1 << PB1)

#define input_port PORTA
#define input_direction DDRA
#define input_pin (1 << PA1)
#define input_pins PINA

#define led_port PORTA
#define led_direction DDRA
#define led_pin (1 << PA2)

#define sol_port PORTA
#define sol_direction DDRA
#define sol_pin (1 << PA0)


void get_char(volatile unsigned char *pins, unsigned char pin, char *rxbyte) {
	//
	// read character into rxbyte on pins pin
	//    assumes line driver (inverts bits)
	//
	*rxbyte = 0;
	while (pin_test(*pins,pin))
	//
	// wait for start bit
	//
	;
	//
	// delay to middle of first data bit
	//
	half_bit_delay();
	bit_delay();
	//
	// unrolled loop to read data bits
	//
	if pin_test(*pins,pin)
	*rxbyte |= (1 << 0);
	else
	*rxbyte |= (0 << 0);
	bit_delay();
	if pin_test(*pins,pin)
	*rxbyte |= (1 << 1);
	else
	*rxbyte |= (0 << 1);
	bit_delay();
	if pin_test(*pins,pin)
	*rxbyte |= (1 << 2);
	else
	*rxbyte |= (0 << 2);
	bit_delay();
	if pin_test(*pins,pin)
	*rxbyte |= (1 << 3);
	else
	*rxbyte |= (0 << 3);
	bit_delay();
	if pin_test(*pins,pin)
	*rxbyte |= (1 << 4);
	else
	*rxbyte |= (0 << 4);
	bit_delay();
	if pin_test(*pins,pin)
	*rxbyte |= (1 << 5);
	else
	*rxbyte |= (0 << 5);
	bit_delay();
	if pin_test(*pins,pin)
	*rxbyte |= (1 << 6);
	else
	*rxbyte |= (0 << 6);
	bit_delay();
	if pin_test(*pins,pin)
	*rxbyte |= (1 << 7);
	else
	*rxbyte |= (0 << 7);
	//
	// wait for stop bit
	//
	bit_delay();
	half_bit_delay();
}
void put_char(volatile unsigned char *port, unsigned char pin, char txchar) {
	//
	// send character in txchar on port pin
	//    assumes line driver (inverts bits)
	//
	// start bit
	//
	clear(*port,pin);
	bit_delay();
	//
	// unrolled loop to write data bits
	//
	if bit_test(txchar,0)
	set(*port,pin);
	else
	clear(*port,pin);
	bit_delay();
	if bit_test(txchar,1)
	set(*port,pin);
	else
	clear(*port,pin);
	bit_delay();
	if bit_test(txchar,2)
	set(*port,pin);
	else
	clear(*port,pin);
	bit_delay();
	if bit_test(txchar,3)
	set(*port,pin);
	else
	clear(*port,pin);
	bit_delay();
	if bit_test(txchar,4)
	set(*port,pin);
	else
	clear(*port,pin);
	bit_delay();
	if bit_test(txchar,5)
	set(*port,pin);
	else
	clear(*port,pin);
	bit_delay();
	if bit_test(txchar,6)
	set(*port,pin);
	else
	clear(*port,pin);
	bit_delay();
	if bit_test(txchar,7)
	set(*port,pin);
	else
	clear(*port,pin);
	bit_delay();
	//
	// stop bit
	//
	set(*port,pin);
	bit_delay();
	//
	// char delay
	//
	bit_delay();
}

void flash() {
	//
	// LED flash delay
	//
	clear(led_port, led_pin);
	led_delay();
	set(led_port, led_pin);
	led_delay();
}

void error_flash() {
	//
	// LED flash delay
	//
	clear(led_port, led_pin);
	long_delay();
	set(led_port, led_pin);
	long_delay();
}

char get_sensor() {
   static char chr;
   static int count = 0;
   while (1) {
      //
      // find framing
      //
      get_char(&serial_pins, serial_pin_in, &chr);
	  //count ++;
      if (chr == '4') {  
		  get_char(&serial_pins, serial_pin_in, &chr);
		  clear(led_port, led_pin);
		  return chr; 
	  }
	  //if (count > 10) {
		//  error_flash();
		  //return '0';
	  //}
   }
}

char get_button() {
   if (0 == pin_test(input_pins,input_pin)){
         return 'd';
	  }
      else {
		  return 'u';
	  }
}

int main(void) {
   //
   // main
   //
   static char cur_sensor;
   static char prev_sensor = 'i';
   static char button;
   static int period;
   //
   // set clock divider to /1
   //
   CLKPR = (1 << CLKPCE);
   CLKPR = (0 << CLKPS3) | (0 << CLKPS2) | (0 << CLKPS1) | (0 << CLKPS0);
   //
   // initialize pins
   //
   set(serial_port, serial_pin_out);
   input(serial_direction, serial_pin_out);
   set(led_port, led_pin);
   output(led_direction, led_pin);
   set(input_port, input_pin); // turn on pull-up
   input(input_direction, input_pin);
   //
   // initialize solenoid pins
   //
   clear(sol_port, sol_pin);
   output(sol_direction, sol_pin);
   //
   // main loop
   //
   while (1) {
	  //
      // Did table move?
      //
          cur_sensor = get_sensor();
         // if (cur_sensor == 'h') {
              // set(sol_port, sol_pin);
              // period = 0;
              // while (period < 16) {
		//	long_delay();
		//	 period ++;
           //    }
           //}
	  if (prev_sensor != 'i' && prev_sensor != cur_sensor){
		  set(sol_port, sol_pin);
		  //clear(led_port, led_pin);
		  period = 0;
		  while (period < 10) {
			long_delay();
			 period ++;
		  }
		  clear(sol_port, sol_pin);
		  //set(led_port, led_pin);
	 }
         prev_sensor = cur_sensor;
	  //
	  // Check buttons
	  //
      button = get_button();
	  if (button == 'd') {
		  set(sol_port, sol_pin);
		  clear(led_port, led_pin);
		  period = 0;
		  while (period < 10) {
			  long_delay();
			  period ++;
		  }
		  clear(sol_port, sol_pin);
		  set(led_port, led_pin);		  
	  }
   }
}