//
//
// hello.temp.45.c
//
// thermistor hello-world
//    9600 baud FTDI interface
// Mani Sai Suryateja Jammalamadaka
// Modified code of Prof. Neil Gershenfeld
// 12/03/18
//
// (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 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 102 // 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 mosfet1_port PORTB
#define mosfet1_direction DDRB
#define mosfet1_pin (1 << PB2) // defining Mosfet1_port which is an output that controls mosfet1

#define mosfet2_port PORTA 
#define mosfet2_direction DDRA
#define mosfet2_pin (1 << PA7) // defining Mosfet2_port which is an ouput that controls mosfet2 

#define serial_port PORTA
#define serial_direction DDRA
#define serial_pin_out (1 << PA1) //defining serial port, PA1 which is connected to Rx of FTDI 

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();
   }

int main(void) {
   //
   // main
   //
   static char chr;
   unsigned char i; //variable
   i=1;
   //
   // 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);
  set(mosfet1_port, mosfet1_pin);
  output(mosfet1_direction, mosfet1_pin);
  set(mosfet2_port, mosfet2_pin);
  output(mosfet2_direction, mosfet2_pin);
   //
   // init A/D
   //
   ADMUX = (0 << REFS1) | (0 << REFS0) // Vcc ref
      | (1 << MUX5)| (1 << MUX4)| (0 << MUX3) 
      | (0 << MUX2) | (0 << MUX1) | (1 << MUX0); // ADC3-ADC2 with 20x gain
   ADCSRA = (1 << ADEN) // enable ADC
      | (1 << ADPS2) | (1 << ADPS1) | (1 << ADPS0); // prescaler /128
   ADCSRB = (1 << BIN)| (0 << ADLAR);  // bipolar mode // right adjust;
   //
   // main loop
   //
   while (1) {
      //
      // send framing
      //
      put_char(&serial_port, serial_pin_out, 1);
      char_delay();
      put_char(&serial_port, serial_pin_out, 2);
      char_delay();
      put_char(&serial_port, serial_pin_out, 3);
      char_delay();
      put_char(&serial_port, serial_pin_out, 4);
      char_delay();
      //Switching the mosfets in alternative readings.
    if (i % 2 == 0) {
     set(mosfet2_port, mosfet2_pin);
     clear(mosfet1_port, mosfet1_pin); //if even reading, switch off mosfet2 and switch on mosfet1
     }
    else {
     set(mosfet1_port, mosfet1_pin);
     clear(mosfet2_port, mosfet2_pin);//if odd reading, switch off mosfet1 and switch on mosfet2
    
      //
      // initiate conversion
      //
     
      ADCSRA |= (1 << ADSC);
      //
      // wait for completion
      //
      while (ADCSRA & (1 << ADSC));
      //
      // send result
      //
      chr = ADCL;
      put_char(&serial_port, serial_pin_out, chr);
      char_delay();
      chr = ADCH;
      put_char(&serial_port, serial_pin_out, chr);
      char_delay();
      i++;
      }
   }