fft_led/main.c

#include<avr/power.h>
#include<util/delay.h>
#include<avr/io.h>
#include"fix_fft.h"
#include"avr_adc.h"
#include"light_ws2812_AVR/Light_WS2812/ws2812_config.h"
#include"light_ws2812_AVR/Light_WS2812/light_ws2812.h"
#include"main.h"

#define STARTADC ADCSRA |= (1<<ADSC)
#define PB_mic PB0
#define NOISE 100
#define SCALE_FACTOR 10
//resolution fft calc: 
//https://3roam.com/fft-resolution-bandwidth-calculator/
//128 samples , 1kSPS  = 7.8Hz
//interested in 0-10000 Hz
// 
//128 bins a 7.8hz = 0...1000Hz
//
//we have 8 leds:
//bands 125hz/band -> 16 bins
//
//1-7.8 - ca 130hz
//2-	255hz
//3-	380
//4-	505
//5-	630
//6-	755
//7-	880
//8-	1kHz
//

int sec;
uint16_t ticks;
int ticks_sample;

ISR(TIMER1_OVF_vect)
{
		ticks_sample++;
		if(ticks < 65000)
		{
				ticks++;
		}
		if(ticks >= 65000)
		{
				ticks=0;
				if(sec<255)
				{
						sec++;
				}
				else
				{
						sec=0;
				}
		}
		

}

int main (void)
{
		int i,i2;
		int i4=0;
		int sum,avg;
		char sample[64];
		char buff[64];

		float fac_r=0.1;
		float fac_g=0.5;
		float fac_b=0.7;
		sec=0;
		ticks=0;
		ticks_sample=0;
		struct cRGB led_bar1[8];
		Fader fader1[4]={{5,5,5},{7,3,2},{3,7,2},{2,3,7}};
		//DDRB = (1<<mic);//would be setting output, default is input so no need for setting
		setupADC();
		setupTimer();

		//OSCCAL = 250;//overclock!!! to 30MHz
		for(i=0;i<8;i++)
		{
				led_bar1[i].r=0;
				led_bar1[i].g=0;
				led_bar1[i].b=0;
		}
		for(i=0;i<64;i++)
		{
				buff[i]=0;
		}

		sei();
		while(1)
		{
				
				//######RECORD SAMPLES######
				sum = 0;
				ticks_sample=0;
				if(sec>3)
				{
						fac_r=(float)fader1[i4].r/10;
						fac_g=(float)fader1[i4].g/10;
						fac_b=(float)fader1[i4].b/10;
						if(i4<3) {i4++;}
						else {i4=0;}
						sec=0;
				}
				for(i=0;i<64;i++)
				{	
						STARTADC; 
						sample[i] = (ADCH-128); //read Analog value register 8bit center -128
						//sample[i] = (sample[i] <= NOISE) ? 0 : (sample[i] - NOISE);						  //noise reduction
						sum+=sample[i];//dc-bias
				}

				avg = sum/64;//calculate bias
				for(i=0;i<64;i++)
				{
						sample[i]-=avg;//remove bias
				}				
				fix_fftr(sample,6,0);
									 
				//####Averaging Data####
				for(i=0;i<64;i++)
				{	
						if(sample[i]<0) sample[i] = 0;
						if(sample[i]>64) sample[i]=64;				//define upper limit
						sample[i] = sample[i] *SCALE_FACTOR;		
						sample[i] = (sample[i]*0.7 + buff[i]*0.3);	//influence of last sample on current sample
						buff[i] = sample[i];						//store sample for next round

				}
				for(i=0;i<8;i++)									//we store 8 frequency domains acros the whole 64 stpectrum
				{
						for(i2=1;i2<=4;i2++)
						{
								sample[i] = ((sample[i] + sample[i*8+i2])/2);//average each 4 following spectrums, write results to sample[0..7]
						}
						if(sample[i]<20)
						{
								led_bar1[i].r=(char)sample[i]*fac_r;
								led_bar1[i].g=(char)sample[i]*fac_g;
								led_bar1[i].b=(char)sample[i]*fac_b;
						}
						else if(sample[i]<30)
						{
								led_bar1[i].r=(char)sample[i]*fac_r*2;
								led_bar1[i].g=(char)sample[i]*fac_g/2;
								led_bar1[i].b=(char)sample[i]*fac_b/2;

						}
						else if(sample[i]<50)
						{
								led_bar1[i].r=(char)sample[i]*fac_r*2;
								led_bar1[i].g=(char)sample[i]*fac_g*2;
								led_bar1[i].b=(char)sample[i]*fac_b*2;
						}
				}				
				ws2812_setleds(led_bar1,8);
				while(ticks_sample<60){asm("");}//workaround for stoping gcc optimizing
		}
return 0;                 
}



void setupTimer(void)
{
		clock_prescale_set(0);
		TCCR1 = (1<<CS10);//|(1<<CS10)|(1<<CTC1);								/8		//clear timer on compare match
		GTCCR = 0;												//default values should be ok
		//OCR1C =	117;											//Compare value of timer / overflow , sets OCF1A
		//OCR1A = 117;
		TIMSK |= (1<<TOIE1);//|(1<<TOIE1);			//timer0 ovf 
		TIFR |=	(1<<TOV1); 			//flag register "aka when to interrupt
}
/*
 * 1/(30Mhz/16384) *255 = 0.139264s  Time for one overflow
 * 			1024		= 0.008704s 
 *			2024		= 0.017204s
 * 						255/0.017204*0.001=15 counts = 1ms
 *			256 gives 1ms
 */