Hey guys,
I've got a new project:
I recently received another 8x8 matrix LED display, powered by the Maxim MAX7219 chip, it works fine with the LED control library.
What i'm having a go at is a really simple graphic equalizer. Now I don't actually do any formal studying of electronics or mathematics so please bare with my lack of ability!
I know of the fourier transform so i'm merely going off my knowledge of that and i've written this code:
#include <math.h>
volatile int16 Sample[256], SampleRead, SampCount;
int16 Wa1[256], Wa2[256], Wa3[256], Wa4[256], Wa5[256], Wa6[256], Wa7[256], Wa8[256];
int16 MidP, NextSamples = 1;
double SineD = 0;
byte Fv = 127;
int16 Bin1, Bin2, Bin3, Bin4, Bin5, Bin6, Bin7, Bin8;
HardwareTimer SampleTimer(2);
void setup(){
SerialUSB.begin();
SampleTimer.pause();
//Create Sine wave arrays
for(int WaveWrite; WaveWrite<256; WaveWrite++){
Wa1[WaveWrite] = 127*sin(SineD); //~70Hz
Wa2[WaveWrite] = 127*sin(SineD*2); //~141Hz
Wa3[WaveWrite] = 127*sin(SineD*4); //~281Hz
Wa4[WaveWrite] = 127*sin(SineD*8); //~563Hz
Wa5[WaveWrite] = 127*sin(SineD*16); //1125Hz
Wa6[WaveWrite] = 127*sin(SineD*32); //2250Hz
Wa7[WaveWrite] = 127*sin(SineD*64); //4500Hz
Wa8[WaveWrite] = Fv; //9000Hz
SineD+=0.024544;
Fv*=-1;
}
pinMode(0, INPUT_ANALOG); //Analog Input (mid biased 2x 1k resistors)
adc_set_sample_rate(ADC1, ADC_SMPR_1_5); //Fastest sampling rate
//Sample rate of 18KHz
SampleTimer.setPrescaleFactor(1);
SampleTimer.setOverflow(3999);
SampleTimer.setChannel1Mode(TIMER_OUTPUT_COMPARE);
SampleTimer.setCompare(TIMER_CH1, 1);
SampleTimer.attachCompare1Interrupt(Sampling);
SampleTimer.refresh();
SampleTimer.resume();
delay(1000);
MidP = analogRead(0); //Find mid point of circuit, no audio applied
}
void loop(){
if(SampCount>=255){
NextSamples = 0; //Stop more samples being processor
//Compute FT, multiply all sine tables by samples and sum to store in bin(s)
for(int FT = 0; FT<256; FT++){
Bin1 += (Sample[FT]*Wa1[FT]);
Bin2 += (Sample[FT]*Wa2[FT]);
Bin3 += (Sample[FT]*Wa3[FT]);
Bin4 += (Sample[FT]*Wa4[FT]);
Bin5 += (Sample[FT]*Wa5[FT]);
Bin6 += (Sample[FT]*Wa6[FT]);
Bin7 += (Sample[FT]*Wa7[FT]);
Bin8 += (Sample[FT]*Wa8[FT]);
}
//Magnitude of bins, shift to 8bit range
Bin1 = (abs(Bin1))>>7;
Bin2 = (abs(Bin2))>>7;
Bin3 = (abs(Bin3))>>7;
Bin4 = (abs(Bin4))>>7;
Bin5 = (abs(Bin5))>>7;
Bin6 = (abs(Bin6))>>7;
Bin7 = (abs(Bin7))>>7;
Bin8 = (abs(Bin8))>>7;
SampCount = 0; //Reset sample counter
NextSamples = 1; //Start next set of samples
}
else{
//While the FT isn't being calculated, print bins, debug only
SerialUSB.print(Bin1);
SerialUSB.print(" ");
SerialUSB.print(Bin2);
SerialUSB.print(" ");
SerialUSB.print(Bin3);
SerialUSB.print(" ");
SerialUSB.print(Bin4);
SerialUSB.print(" ");
SerialUSB.print(Bin5);
SerialUSB.print(" ");
SerialUSB.print(Bin6);
SerialUSB.print(" ");
SerialUSB.print(Bin7);
SerialUSB.print(" ");
SerialUSB.println(Bin8);
}
}
void Sampling(){
//Samples done here
if(NextSamples==1){
SampleRead = (analogRead(0) - MidP)>>4; //Sample and subtract midpoint(constant), shift to 8 bit range
Sample[SampCount] = SampleRead; //Store samples in array
SampCount++; //Increment sample counter
}
}
As you can see, its creating 8 sine wave arrays of different frequencies in the setup and once a full 256 array of samples has been done, carrying out a real only fourier transform on the sample array (no phase).
What I then want to do with the 8 bins is convert them into 3 bit values to then be used to drive my graphic LED.
The only problem i'm having is when I upload this code, the LED on my maple just throbs at me and it doesn't want to do anything. What seems to be wrong with my code and how can I fix it? I've tried replacing the "next samples" section for timer pause and refresh/resume but this still caused the throbbing LED problem. My maple still works as I can upload the blink program successfully.
Thanks,
Harris
