#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

// add macros for load sensing
#define bit_delay_time 51 // bit delay for 9600 with overhead for 20 MHz clock
#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 charge_delay_1() _delay_us(1) // charge delay 1
#define charge_delay_2() _delay_us(10) // charge delay 2
#define charge_delay_3() _delay_us(100) // charge delay 3
#define settle_delay() _delay_us(100) // settle delay
#define char_delay() _delay_ms(10) // char delay



char SINE_LENGTH = 101;
char SINEWAVE[101] ={128,136,143,151,159,167,174,182,189,196,202,209,215,220,226,231,235,239,243,246,249,251,253,254,255,255,255,254,253,251,249,246,243,239,235,231,226,220,215,209,202,196,189,182,174,167,159,151,143,136,128,119,112,104,96,88,81,73,66,59,53,46,40,35,29,24,20,16,12,9,6,4,2,1,0,0,0,1,2,4,6,9,12,16,20,24,29,35,40,46,53,59,66,73,81,88,96,104,112,119,127};




#define MOSFET_PIN_A (1 << PA7)
#define MOSFET_PIN_B (1 << PB2) // output locations
#define TRIG_PIN (1<<PA3)
#define MOSFET_port PORTB

#define ARD_PA7 (7)
#define ARD_PB2 (8)
#define ARD_TRIG_PIN (3)

// now add stuff for step response sensing (and output if desired)

#define serial_port PORTA
#define serial_direction DDRA
#define serial_pins PINA
#define serial_pin_out (1 << PA1) // redefine port that talks to FTDI
#define serial_pin_in (1 << PA0) // now for character input

#define charge_port PORTA
#define charge_direction DDRA
#define charge_pin (1 << PA3) // redefine charge port to initiate step response

#define char_delay() _delay_ms(10) // delay in between characters



void setup(){}

void play_sine(int dSamps, int Cycs){ // frequency set by dSamps, number of cycles by Cycs
  for (int c = 0; c < Cycs; c++){
    for (int s = 0; s < SINE_LENGTH; s++){ // iterate over sine wave samples
      OCR0A = SINEWAVE[s];
      delayMicroseconds(dSamps);
    }
  }
}

char 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();

   // NEW FOR THIS: SET CHAR TO CONTROL PWM
   //OCR0A = *rxbyte;
   //play_sine(*rxbyte,1);
   }

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 loop() {
  // put your setup code here, to run once:

  static unsigned char up_lo,up_hi,down_lo,down_hi,PWM_val;
  static unsigned short PWM_short;
  // set clock prescaler to to 1
  CLKPR = (1 << CLKPCE);
  CLKPR = (0 << CLKPS3) | (0 << CLKPS2) | (0 << CLKPS1) | (0 << CLKPS0);
  
  // now, set WGM02:0 to 0x03 to enable fast PWM mode on OCR0B, OCR0A
  TCCR0B &= (~0x08); // clearing WGM02, and:
  TCCR0A |= 0x03; // setting WGM00, WGM01
  
  TCCR0B |= 0x01; TCCR0B &= (~0x06); //set clock divider to 1 for max speed

  // and set pin PA7 to output OCR0B output
  TCCR0A |= 0x20; // setting pin COM0B1 for non-inverting mode
  // TCCR0A |= 0x10; // un-commenting this line sets COM0B0 for inverting mode

  // and set pin PB2 to output OCR0A output
  TCCR0A |= 0x80; // setting pin COM0A1 for non-inverting mode
  // TCCR0A |= 0x40; // un-commenting this line sets COM0A0 to inverting mode

  // set data direction registers for proper I/O
  clear(PORTA, MOSFET_PIN_A); clear(PORTB, MOSFET_PIN_B);
  output(DDRA, MOSFET_PIN_A);
  output(DDRB, MOSFET_PIN_B);
  input(DDRA, TRIG_PIN);

  // also initiate input and FTDI pins
  set(serial_port, serial_pin_out);
  output(serial_direction, serial_pin_out);
  clear(charge_port, charge_pin);
  output(charge_direction, charge_pin);
  //
  // init A/D
  //
  ADMUX = (0 << REFS1) | (0 << REFS0) // Vcc ref
     | (0<<MUX5) | (0 << MUX4) | (0 << MUX3) | (0 << MUX2) | (1 << MUX1) | (0 << MUX0); // now sensing on PA2, rather than PB4; still ADC2 (on ATTiny44)

  ADCSRA = (1 << ADEN) // enable
     | (1 << ADPS2) | (1 << ADPS1) | (1 << ADPS0); // prescaler /128
     
 
  // framing bytes
  static char F1 = 0; static char F2 = 0; static char F3 = 0; static char F4 = 0;
  static char Ftmp;
 // data byte
  static char chr = 0;
  OCR0A = 0x00;

 // MAIN LOOP
  while(1){
      char_delay();
      //get_char(&serial_pins, serial_pin_in, &Ftmp);
      //F1 = F2; F3 = F2; F4 = F3; F4 = Ftmp;

      // if framing bits correct
      //if ((F1==1)&(F2==2)&(F3==3)&(F4==4)){
        get_char(&serial_pins, serial_pin_in, &chr);
        OCR0A = chr; // output value to PWM
      //}
  }
}