//
//
// hello.bus.45mod.c
//
// 9600 baud serial bus
// adresses the bus nodes individually 
// modified slightly by C. Teissl from Neil Gershenfeld
//


#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 led_delay() _delay_ms(200) // LED flash delay

#define led_port PORTB
#define led_direction DDRB
#define led_pin (1 << PB0)

#define serial_port PORTB
#define serial_direction DDRB
#define serial_pins PINB
#define serial_pin_in (1 << PB3)
#define serial_pin_out (1 << PB4)

#define node_id 'z'

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(int flashes) {
   //
   // LED flash delay
   //
   
   static int index;  
   
   
   //for(index = 0;index <= (node_id-49);index++) //'1' = ascii 49 
   
   for(index = 1;index <= flashes;index++) 
     {
           clear(led_port, led_pin);
        led_delay();
        set(led_port, led_pin);    
        led_delay();      
     }
   
     
   }

int main(void) {
   //
   // main
   //
   static char chr;
   int steps;
   
   //
   // 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);            // PORTB, PB4 (=RX) 
   input(serial_direction, serial_pin_out);        // DDRB, PB4 as IN
   
   set(led_port, led_pin);                        // PORTB, PB0
   output(led_direction, led_pin);                // DDRB, PB0 as OUT
   
   //
   // main loop
   //
   while (1) {
      
      
      
      
      do{
          get_char(&serial_pins, serial_pin_in, &chr);               // PB3 (=TX)
        }
      while ((chr < 48) || (chr > 57));                            // until chr is number
            
      steps = chr-48;                                                 // ASCII 0-9
            
      do{
          get_char(&serial_pins, serial_pin_in, &chr);               // PB3 (=TX)
        }
      while (!((chr == 'x') || (chr == 'y') || (chr == 'z')));     // until chr is x,y, or z
  
          
           
      if (chr == node_id) {                        
         output(serial_direction, serial_pin_out);        // node-id-board only
         static const char message[] PROGMEM = "node ";
         put_string(&serial_port, serial_pin_out, (PGM_P) message);  // array of char
         put_char(&serial_port, serial_pin_out, chr);
         put_char(&serial_port, serial_pin_out, 10); // new line
         led_delay();
         flash(steps);
         input(serial_direction, serial_pin_out);
         }
      }
   }