Revision 0:e60134beb2ca, committed 2012-06-14
- Comitter:
- ddobano
- Date:
- Thu Jun 14 10:59:08 2012 +0000
- Commit message:
Changed in this revision
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp Thu Jun 14 10:59:08 2012 +0000
@@ -0,0 +1,158 @@
+#include "mbed.h"
+
+
+DigitalOut myled(LED1);
+DigitalOut led(LED2);
+DigitalOut led2(LED3);
+DigitalOut led3(LED4);
+const int N=1024; // Sample number
+struct TWIDDLE { // Structure factor for calculate fft
+
+ float cosval [N/2];
+ float sinval [N/2];
+
+};
+void FFT(float datos[N], int n, TWIDDLE &w); //Declaration of functions
+void enviodatos(float datos[N], int n);
+Serial pc(USBTX, USBRX); //Declaration Serial port
+
+int main() { //Main program
+ myled.write(0);
+ led.write(0);
+ led2.write(0);
+ led3.write(0);
+ int i; //Parameters to calculate the values of a sine function. DATOS[N]=Amp*sin(w0*t)
+ float arg;
+ arg=2*3.1416/N; //argument of the structure TWIDDLE
+ float tm,t,w0,T, Amp;
+ tm=0.1; // increments of time (0,1seg)
+ t=0; //initial time
+ T=2*3.1416; //Period of signal
+ w0=(2*3.1416/T); // angular frequency
+ Amp=3; //Amplitude
+ struct TWIDDLE W; //Declarate of a type structure
+
+ for (i=0; i<N/2; i++) { //Calculate all the TWIDDLE factors
+ W.cosval[i]= cos(i*arg);
+ W.sinval[i]= -sin(i*arg);
+ }
+
+ float DATOS[N]; //array to save the sinus values
+ for (i=0; i<N; i++) { //calculate the sinus values
+ DATOS[i]=Amp*sin(w0*t);
+ t+=tm;
+ }
+ led.write(1); //Execution of the program to here OK
+ FFT(DATOS,N,W); //Function to calculate FFT
+ enviodatos(DATOS,N); //Function to send values to serial port
+ led3.write(1); //Execution of the program to here OK
+ while (1); //
+
+}
+
+void FFT(float datos[N], int n,TWIDDLE &w) {
+ float temp1, temp2, temp3,temp4; //variables needed to calculate FFT
+ int i,j,k,p;
+ int upper_leg, lower_leg;
+ int leg_diff;
+ int num_stages=0;
+ int index, step;
+ float datos_real[n], datos_imag[n]; //real and imaginary values
+ for (p=0; p<n; p++) {
+ datos_real[p]=datos[p];
+ datos_imag[p]=0;
+ }
+ led2.write(1); // Execution of the program to here break it if N=>2048, else OK.
+ i=1;
+ do {
+ num_stages+=1;
+ i=i*2;
+ } while (i!=n);
+
+ leg_diff=n/2;
+ step=1;
+
+ for (i=0; i<num_stages; i++) {
+ index=0;
+ for (j=0; j<leg_diff; j++) {
+ for (upper_leg=j; upper_leg<n; upper_leg+=(2*leg_diff)) {
+ lower_leg=upper_leg+leg_diff;
+
+ temp1= (datos_real[upper_leg]+ datos_real[lower_leg]);
+ temp2= (datos_real[upper_leg]- datos_real[lower_leg]);
+ temp3= (datos_imag[upper_leg]+ datos_imag[lower_leg]);
+ temp4= (datos_imag[upper_leg]- datos_imag[lower_leg]);
+ datos_real[lower_leg]= (temp2*w.cosval[index])-(temp4*w.sinval[index]);
+ datos_imag[lower_leg]= (temp2*w.sinval[index]+temp4*w.cosval[index]);
+ datos_real[upper_leg]= temp1;
+ datos_imag[upper_leg]= temp3;
+ }
+ index+=step;
+ }
+ leg_diff=leg_diff/2;
+ step*=2;
+ }
+//bit reversal
+
+ j=0;
+ for (i=1; i<(N-2); i++) {
+ k=n/2;
+ while (k<=j) {
+ j=j-k;
+ k=k/2;
+ }
+ j=j+k;
+
+ if (i<j) {
+ temp1= datos_real[j];
+ temp2= datos_imag[j];
+ datos_real[j]=datos_real[i];
+ datos_imag[j]=datos_imag[i];
+ datos_real[i]=temp1;
+ datos_imag[i]=temp2;
+ }
+ }
+
+ for (i=0; i<n; i++) {
+
+ datos[i]= pow(sqrt(pow(datos_real[i],2)+pow(datos_imag[i],2)),2); //Calculate the power fft
+ };
+
+}
+
+void enviodatos(float datos[N],int n) {
+ int i=0,j=0,k=0,aux=0; //send to serial port the values correctly.
+ unsigned char bytes[4];
+ float dato;
+
+ for (i=0; i<n; i++) {
+ dato=datos[i];
+ aux=dato;
+ for (j=0; j<4; j++) {
+ switch (j) {
+ case 0:
+ bytes[j]=aux;
+ aux=aux>>8;
+ break;
+ case 1:
+ bytes[j]=aux;
+ aux=aux>>8;
+ break;
+ case 2:
+ bytes[j]=aux;
+ aux=aux>>8;
+ break;
+ case 3:
+ bytes[j]=aux;
+ aux=aux>>8;
+ break;
+ }
+ }
+ for (k=3; k>=0; k--) {
+
+ while (pc.writeable()==0);
+ pc.putc(bytes[k]);
+
+ }
+ }
+}
\ No newline at end of file
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/mbed.bld Thu Jun 14 10:59:08 2012 +0000
@@ -0,0 +1,1 @@
+http://mbed.org/users/mbed_official/code/mbed/builds/737756e0b479