//
//
// hello.array.44.c
//
// Charlieplex LED array hello-world
//
// Neil Gershenfeld
// 11/13/10
//
// (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>

#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 led_delay() _delay_ms(1) // LED delay

#define led_port PORTA
#define led_direction DDRA

#define A (1 << PA1) // row 1
#define B (1 << PA2) // row 2
#define C (1 << PA3) // row 3
#define D (1 << PA4) // row 4
#define E (1 << PA5) // row 5

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

int main(void) {
  //
  // set clock divider to /1
  //
  CLKPR = (1 << CLKPCE);
  CLKPR = (0 << CLKPS3) | (0 << CLKPS2) | (0 << CLKPS1) | (0 << CLKPS0);
  //
  // main loop
  //
  while (1) {
       led_cycle(100,1);
       }
   }