//
//
// brain.bus.44.node.c
//
// 9600 baud serial bus
//
// Shirin Shivaei
// 11/12/16
//
//

#include <avr/io.h>
#include <util/delay.h>
#include <avr/pgmspace.h>
#include <string.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 100 // 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 settle_delay() _delay_us(100) // settle delay
#define char_delay() _delay_ms(10) // char delay
#define nloop 100 // loops to accumulate
#define led_delay() _delay_ms(100) // LED flash delay

#define led_port PORTA
#define led_direction DDRA
#define led_1_pin (1 << PA0)
#define led_2_pin (1 << PA1)
#define led_3_pin (1 << PA4)

#define serial_port PORTA
#define serial_direction DDRA
#define serial_pins PINA
#define serial_pin_in (1 << PA3)
#define serial_pin_out (1 << PA2)

// txrx sensor macros
#define transmit_port PORTB
#define transmit_direction DDRB
#define transmit_pin (1 << PB1)

#define node_id '1'

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 put_string(volatile unsigned char *port, unsigned char pin, PGM_P str) {
   //
   // send character in txchar on port pin
   //    assumes line driver (inverts bits)
   //
   static char chr;
   static int index;
   index = 0;
   do {
      chr = pgm_read_byte(&(str[index]));
      put_char(&serial_port, serial_pin_out, chr);
      ++index;
      } while (chr != 0);
   }

void flash(uint8_t led_pin) {
   //
   // LED flash delay
   //
   clear(led_port, led_pin);
   led_delay();
   set(led_port, led_pin);
   }

int main(void) {
   //
   // main
   //
   static unsigned char count;
   static uint16_t up, down;
   static int16_t lastup,lastdown;
   static int16_t deltaup, deltadown;// to track changes between loops
   static int16_t diff;
   static uint16_t upS, downS;

   static char chr;
   //
   // set clock divider to /1
   //
   CLKPR = (1 << CLKPCE);
   CLKPR = (0 << CLKPS3) | (0 << CLKPS2) | (0 << CLKPS1) | (0 << CLKPS0);
   //
   // initialize output pins
   //
   set(serial_port, serial_pin_out);
   input(serial_direction, serial_pin_out);
   set(led_port, led_1_pin);
   set(led_port, led_2_pin);
   set(led_port, led_3_pin);
   output(led_direction, led_1_pin);
   output(led_direction, led_2_pin);
   output(led_direction, led_3_pin);
   clear(transmit_port, transmit_pin);
   output(transmit_direction, transmit_pin);
   // 
   // main loop
   // 
   while (1) {
      //
      // accumulate
      //
      // We measure 100 times to get sqrat(100) = 10 times resolution
      up = 0;
      down = 0;
      for (count = 0; count < nloop; ++count) { 
         //
         // settle, charge
         //
         settle_delay();
         set(transmit_port, transmit_pin);
         //
         // initiate conversion
         //
         ADCSRA |= (1 << ADSC);
         //
         // wait for completion
         //
         while (ADCSRA & (1 << ADSC))
            ;
         //
         // save result
         //
         up += ADC;
         //
         // settle, discharge
         //
         settle_delay();
         clear(transmit_port, transmit_pin);
         //
         // initiate conversion
         //
         ADCSRA |= (1 << ADSC);
         //
         // wait for completion
         //
         while (ADCSRA & (1 << ADSC))
            ;
         //
         // save result
         //
         down += ADC;
         }
      //
      deltaup = up-down;
      diff = deltaup - lastup;
      if (diff<0) {upS = -diff;}
      else {upS = diff;}
      lastup = deltaup;

      // 
      // if diff>threshhold:
      // send a high signal to bridge
      // turn leds on 
      // keep them on for 30 sec? (ideally until another node becomes active)
      // 

      if(diff>1000){
         output(serial_direction, serial_pin_out);
         static const char message[] PROGMEM = "node ";
         put_string(&serial_port, serial_pin_out, (PGM_P) message);
         put_char(&serial_port, serial_pin_out, node_id);
         put_char(&serial_port, serial_pin_out, 10); // new line
         led_delay();
         flash(led_1_pin);
         flash(led_2_pin);
         flash(led_3_pin);
         input(serial_direction, serial_pin_out);
      }
   //
   // main loop (for debugging)
   //
   // while (1) {
   //    get_char(&serial_pins, serial_pin_in, &chr);
   //    flash();
   //    if (chr == node_id) {
   //       output(serial_direction, serial_pin_out);
   //       static const char message[] PROGMEM = "node ";
   //       put_string(&serial_port, serial_pin_out, (PGM_P) message);
   //       put_char(&serial_port, serial_pin_out, chr);
   //       put_char(&serial_port, serial_pin_out, 10); // new line
   //       led_delay();
   //       flash(led1_pin);
   //       input(serial_direction, serial_pin_out);
   //       }
   //    }
      }
   }