//
//
// mbta.interface.c
//
// Charlieplex LED array hello-world
//
// Neil Gershenfeld
// 11/13/10
// 
// Modified 11/17/15 by Caroline Jaffe
//
// (c) Massachusetts Institute of Technology 2010
// 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>
#include <avr/pgmspace.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 103 // 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(1) // LED delay

#define led_port PORTA
#define led_direction DDRA

#define A (1 << PA0)
#define B (1 << PA1)
#define C (1 << PA2)
#define D (1 << PA3) 
#define E (1 << PA4) 
#define F (1 << PA5) 

#define serial_port PORTB
#define serial_direction DDRB
#define serial_pins PINA
#define serial_pin_in (1 << PA7)
#define serial_pin_out (1 << PB0)

#define max_buffer 25
#define num_leds 30
#define long_delay 200

void flash(uint8_t from, uint8_t to, uint8_t delay) {
   //
   // source from, sink to, flash
   //
   static uint8_t i;
   set(led_port,from);
   clear(led_port,to);
   output(led_direction,from);
   output(led_direction,to);
   for (i = 0; i < delay; ++i)
       led_delay();
   input(led_direction,from);
   input(led_direction,to);
   }

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, char *str) {
   //
   // print a null-terminated string
   //
   static int index;
   index = 0;
   do {
      put_char(port, pin, str[index]);
      ++index;
      } while (str[index] != 0);
   }

uint8_t macro_conv(char c) {
   if (c == 'F')
      return F;
   else if (c == 'E') 
      return E;
   else if (c == 'D')
      return D;
   else if (c == 'C')
      return C;
   else if (c == 'B')
      return B;
   else if (c == 'A')
      return A;
   return A;
}

void led_cycle2(char* anode, char* cathode, uint8_t delay) {
   uint8_t i;
   for (i=0; i<num_leds; i++) {
      flash(macro_conv(anode[i]), macro_conv(cathode[i]), delay);
   }
}

void flash_by_id(char* anode, char* cathode, uint8_t id, uint8_t delay) {
   flash(macro_conv(anode[id]), macro_conv(cathode[id]), delay);
}

void led_cycle(uint8_t number, uint8_t delay) {
   //
   // cycle through LEDs
   //
   uint8_t i;
   for (i = 0; i < number; ++i) {
      flash(F,A,delay);
      flash(F,B,delay);
      flash(F,C,delay);
      flash(F,D,delay);
      flash(F,E,delay);
      flash(E,A,delay);
      flash(E,B,delay);
      flash(E,C,delay);
      flash(E,D,delay);
      flash(E,F,delay);
      flash(D,A,delay);
      flash(D,B,delay);
      flash(D,C,delay);
      flash(D,E,delay);
      flash(D,F,delay);
      flash(C,A,delay);
      flash(C,B,delay);
      flash(C,D,delay);
      flash(C,E,delay);
      flash(C,F,delay);
      flash(B,A,delay);
      flash(B,C,delay);
      flash(B,D,delay);
      flash(B,E,delay);
      flash(B,F,delay);
      flash(A,B,delay);
      flash(A,C,delay);
      flash(A,D,delay);
      flash(A,E,delay);
      flash(A,F,delay);
      }
   }

int main(void) {
   //
   // main
   //
   static char chr;
   static char buffer[max_buffer] = {0};
   static int index;
   static char anode[] = "FFFFFEEEEEDDDDDCCCCCBBBBBAAAAA";
   static char cathode[] = "ABCDEABCDFABCEFABDEFACDEFBCDEF";
   int val;
   //
   // 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);
   output(serial_direction, serial_pin_out);
   //
   // main loop
   //
   index = 0;
   while (1) {
      get_char(&serial_pins, serial_pin_in, &chr);
      if (chr == 'x') {
         put_string(&serial_port, serial_pin_out, "The LED ID you typed is: ");
         put_string(&serial_port, serial_pin_out, buffer);
         put_string(&serial_port, serial_pin_out, "\n\r");
         val = atoi(buffer);
         if (val <= 30) {
            flash_by_id(anode, cathode, val-1, long_delay);
            put_string(&serial_port, serial_pin_out, "You just flashed LED #");
            put_string(&serial_port, serial_pin_out, buffer);
            put_string(&serial_port, serial_pin_out, "\n\r");
         } else {
            put_string(&serial_port, serial_pin_out, "That is not a valid LED ID\n\r");
         }
         memset(buffer, 0, sizeof(buffer));
         put_string(&serial_port, serial_pin_out, "You cleared your string\n\r");
         index = 0;
      } else {
         put_string(&serial_port, serial_pin_out, "mbta.interface.c: you typed \"");
         buffer[index++] = chr;
         if (index == (max_buffer-1))
            index = 0;
         put_string(&serial_port, serial_pin_out, buffer);
         put_char(&serial_port, serial_pin_out, '\"');
         put_string(&serial_port, serial_pin_out, "\n\r");
      }
      }
   }