//
// 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.
//

#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 serial_port PORTB
#define serial_direction DDRB
#define serial_pin_out (1 << PB2)//|(1 << PB3) //PB# is for clap detection

#define serial_pin_out_clap (1 << PB3)//|(1 << PB2)
#define NPTS 100 // points in buffer ; This was 100 before, but now with 125 it leads to 98% workload


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 delay_3s(void)
{
    uint8_t i;
    for (i = 0; i < 255; i++)
        _delay_ms(1); //for whatever reason it corresponds to 3s instead of 0.3s
}

int main(void) {
   //
   // main
   //
    unsigned char currADCL,currADCH,onoroff,waitornot,clap_2,thr;
    
    //delay_3s(); //a short delay before we start messing with the clock rate
    _delay_ms(300); //This is exactly 3s
   //
   // set clock divider to /1
   //
   CLKPR = (1 << CLKPCE); //here we enable the chane of CLKPS bits
   CLKPR = (0 << CLKPS3) | (1 << CLKPS2) | (0 << CLKPS1) | (1 << CLKPS0); // /32 clock divider
   //
   // initialize output pins
   //
   set(serial_port, serial_pin_out);
   output(serial_direction, serial_pin_out);
   //my code for LED
    set(serial_port, serial_pin_out_clap); //pull up for the LED and turn it on
    output(serial_direction, serial_pin_out_clap);
    //clear(serial_port, serial_pin_out_clap); //turn led off
    
   //
   // init A/D
   //
   ADMUX = (0 << REFS2) | (1 << REFS1) | (0 << REFS0) // 1.1V ref
      | (0 << MUX3) | (0 << MUX2) | (1 << MUX1) | (0 << MUX0); // PB4, which is from the microphone input
   ADCSRA = (1 << ADEN) // enable ADC
      | (1 << ADPS2) | (1 << ADPS1) | (0 << ADPS0); // prescaler /64 -  the division factor between the system clock frequency and the input clock to the ADC.
    
    // start counter
    //
    TCCR0B |= (1 << CS00)|(1 << CS02); // /1024 prescaling for timer, corr. to 1024*32*255/8e6=1.044s period
   //and 8.188e-3s timer step
    clap_2=0;
    onoroff=1;
    waitornot=0;
    thr = 0x7D;//0x8D;
    //
    //
   // main loop
   //
    while (1) {
        // initiate conversion
        //
        ADCSRA |= (1 << ADSC); //ADSC value returns to zero after conversion is complete
        //
        // wait for completion
        //
        while (ADCSRA & (1 << ADSC))
            ;
        //
        // save result
        //
        currADCL = ADCL;  //2 extra bits
        currADCH = ADCH; //8 bit precision*/
        
        if ((currADCL>thr) & (waitornot==0)) { //here we detect the first clap
            TCNT0 = 0; //counter value is zeroed
            TIFR |= (1 << TOV0); //TOV0 is cleared
            clap_2=0;
            waitornot = 1;
        }
        if (((TCNT0>24) & (TCNT0<44)) & (currADCL>thr)) { //from 100ms to 180ms after first clap it should be quiet
            waitornot=0;
        }
        if (((TCNT0>44) & (TCNT0<73)) & ((waitornot==1) & (currADCL>thr))) { //from 180ms to 300ms from first clap we can start expecting the 2nd one
            clap_2=1;
        }
        if (((waitornot==1) & (TCNT0==73)) & (clap_2==0)) { //by 300ms from first clap we should have had the 2nd one
            waitornot=0;
        }
        if ((TCNT0>73) & (currADCL>thr)) { //after the second clap (300ms) until the end it should be quiet again
            waitornot=0;
        }
        if ((TCNT0==0xFF) & (waitornot==1)) {
            if (onoroff==0)
                set(serial_port, serial_pin_out_clap);
            else
                clear(serial_port, serial_pin_out_clap);
            onoroff=1-onoroff;
            waitornot=0;
        }
    }
}