//
//
// hello.ftdi.44.echo.c
//
// 115200 baud FTDI character echo, with flash string
//
// set lfuse to 0x7E for 20 MHz xtal
//
// Neil Gershenfeld
// 12/8/10
//
// (c) Massachusetts Institute of Technology 2010
// Permission granted for experimental and personal use;
// license for commercial sale available from MIT.
//

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

#define output(directions,pin) (directions |= pin) // set port direction for output
#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 8.5 // bit delay for 115200 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 PWM_delay() _delay_us(10) // PWM delay

#define serial_port PORTA
#define serial_direction DDRA
#define serial_pins PINA
#define serial_pin_in (1 << PA0)
#define serial_pin_out (1 << PA1)

#define max_buffer 25

#define led_port PORTA
#define led_direction DDRA
#define red (1<<PA7)
#define blue (1<<PA2)
#define green (1<<PA3)

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_flash_string(volatile unsigned char *port, unsigned char pin, PGM_P str) {
   //
   // print a null-terminated string from flash
   //
   static char chr;
   static int index;
   index = 0;
   do {
      chr = pgm_read_byte(&(str[index]));
      put_char(port, pin, chr);
      ++index;
      } while (chr != 0);
   }

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

int main(void) {
   //
   // main
   //
   static char chr;
   static char buffer[max_buffer] = {0};
   static int index;
   unsigned char count, pwm;
   //
   // set clock divider to /1
   //
   CLKPR = (1 << CLKPCE);
   CLKPR = (0 << CLKPS3) | (0 << CLKPS2) | (0 << CLKPS1) | (0 << CLKPS0);
   //
   // initialize output pins
   //
   set(led_port, red);
   output(led_direction, red);
   set(led_port, green);
   output(led_direction, green);
   set(led_port, blue);
   output(led_direction, blue);

   //
   // main loop
   //
   index = 0;
   while (1) {
      //
      // off -> red
      //
      //DDRA |= (1<<red);
      //DDRA &= ~((1<<blue)|(1<<green));
      for (count = 0; count < 255; ++count) {
         clear(led_port,red);
         for (pwm = count; pwm < 255; ++pwm)
            PWM_delay();
         set(led_port,red);
         for (pwm = 0; pwm < count; ++pwm)
            PWM_delay();
         }
      //
      // red -> green
      //
      for (count = 0; count < 255; ++count) {
         set(led_port,red);
         clear(led_port,green);
         for (pwm = count; pwm < 255; ++pwm)
            PWM_delay();
         clear(led_port,red);
         set(led_port,green);
         for (pwm = 0; pwm < count; ++pwm)
            PWM_delay();
         }
      //
      // green -> blue
      //
      for (count = 0; count < 255; ++count) {
         set(led_port,green);
         clear(led_port,blue);
         for (pwm = count; pwm < 255; ++pwm)
            PWM_delay();
         clear(led_port,green);
         set(led_port,blue);
         for (pwm = 0; pwm < count; ++pwm)
            PWM_delay();
         }
      //
      // blue -> on
      //
      for (count = 0; count < 255; ++count) {
         set(led_port,blue);
         clear(led_port,green);
         clear(led_port,red);
         for (pwm = count; pwm < 255; ++pwm)
            PWM_delay();
         set(led_port,blue);
         set(led_port,green);
         set(led_port,red);
         for (pwm = 0; pwm < count; ++pwm)
            PWM_delay();
         }

      //
      // on -> off
      //
      for (count = 0; count < 255; ++count) {
         set(led_port,blue);
         set(led_port,green);
         set(led_port,red);
         for (pwm = count; pwm < 255; ++pwm)
            PWM_delay();
         clear(led_port,blue);
         clear(led_port,green);
         clear(led_port,red);
         for (pwm = 0; pwm < count; ++pwm)
            PWM_delay();
         }
      


      //if (PORTA & (1 << PA2)){
         // DDRA |= (1<<PA2);
         // DDRA &= ~((1<<PA7)|(1<<PA3));
         // set(PORTA,(1 << PA2));
         // _delay_ms(100);
         // clear(PORTA,(1 << PA2));
         // _delay_ms(100);
      //} else {
      //   clear(PORTA,(1 << PA7));
      //}
      
      
      // get_char(&serial_pins, serial_pin_in, &chr);
      // static char message[] PROGMEM = "hello.ftdi.44.echo.c: you typed \"";
      // put_flash_string(&serial_port, serial_pin_out, (PGM_P) message);
      // buffer[index++] = chr;
      // if (index == (max_buffer-1))
      //    index = 0;
      // put_ram_string(&serial_port, serial_pin_out, buffer);
      // put_char(&serial_port, serial_pin_out, '\"');
      // put_char(&serial_port, serial_pin_out, 10); // new line
      }
   }