//
// hello.SPU0414HR5H.c
//
// SPU0414HR5H microphone hello-world
//    9600 baud FTDI interface
//
// Neil Gershenfeld 11/17/15
// (c) Massachusetts Institute of Technology 2015
//
// 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.
//
//
// Modified by: Yasushi Sakai 11/23/15
//
//
//

#include <avr/io.h>
#include <util/delay.h>
#include <math.h>
#include <stdlib.h>
#include <stdio.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 serial_port PORTB
#define serial_direction DDRB
#define serial_pin_out (1 << PB2)
#define NPTS 25 // points in buffer

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){
    put_char(&serial_port,serial_pin_out,0);
    int i=0;
    do{
      put_char(port,pin,str[i]);
    }while(str[++i]!=0);
  }


int main(void) {
   //
   // main
   //
   static unsigned char i,array_lo[NPTS],array_hi[NPTS];

   unsigned int result;
   float baseline;
   unsigned int diff_max;
   //
   // 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);
   //
   // init A/D
   //
   // out input pin is PA 7
   ADMUX = (1 << REFS1) | (0 << REFS0) | (0 << MUX5) | (0 << MUX4) | (0 << MUX3)  | (1 << MUX2)  | (1 << MUX1)  | (1 << MUX0);
   ADCSRA = (1 << ADEN) // enable
      | (1 << ADPS2) | (1 << ADPS1) | (0 << ADPS0); // prescaler /64
   //
   // main loop
   //
   baseline = 0;
   while (1) {
     diff_max = 0;
      //
      // 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();

      // free-running sample loop
      //
      for (i = 0; i < NPTS; ++i) {
         //
         // initiate conversion
         //
         ADCSRA |= (1 << ADSC);
         //
         // wait for completion
         //
         while (ADCSRA & (1 << ADSC))
            ;
         //
         // save result
         //
         array_lo[i] = ADCL;
         array_hi[i] = ADCH;
         }
      for (i = 0; i < NPTS; ++i) {
         //
         // send result
         //
         //put_char(&serial_port, serial_pin_out, array_lo[i]);
         //put_char(&serial_port, serial_pin_out, array_hi[i]);
         result = array_hi[i]*255 + array_lo[i];
         baseline = 0.01 * (float)result + (1.0-0.01) * baseline;
         if(diff_max < abs(result-(int)baseline)) diff_max = abs(result-(int)baseline);
         }
         put_char(&serial_port,serial_pin_out,(diff_max)%256); // lo
         char_delay();
         put_char(&serial_port,serial_pin_out,(diff_max)/256); // hi

         //char str[10];
         //sprintf(str,"%d",diff_max);
         //put_string(&serial_port,serial_pin_out,str);
         //put_char(&serial_port,serial_pin_out,44);

         _delay_ms(100);
      }
   }