Diff: main.cpp

Revision:

0:b6451e68016a

Child:

1:ef3ad9c720c9

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Mon Feb 28 03:26:53 2011 +0000
@@ -0,0 +1,123 @@
+
+
+
+
+#include "mbed.h"
+#include "adc.h"
+#include "NokiaLCD.h"
+
+#define MN 256 /*Number of points*/
+#define SAMPLE_RATE   48000
+NokiaLCD lcd(p5, p7, p8, p9, NokiaLCD::LCD6610); // mosi, sclk, cs, rst, type
+
+
+//Going to use the Mellen FFT rather than STM, as the STM (port by Igor) won't compile
+//extern "C" void cr4_fft_256_stm32(void *pssOUT, void *pssIN, uint16_t Nbin);
+extern "C" void fftR4(short *y, short *x, int N);
+
+//use the LED as a bargraph
+DigitalOut l1(LED1);
+DigitalOut l2(LED2);
+DigitalOut l3(LED3);
+DigitalOut l4(LED4);
+
+//set up a timer for timing FFT's
+Timer timer;
+Ticker ticker;
+
+//Set up filesystem so we can write some useful files
+LocalFileSystem local("local");
+FILE *fp;
+
+
+//Set up a global buffer for audio data so interrupt can access it
+int Counter = 0;
+int16_t Buffer[5000];
+
+
+//Initialise ADC to maximum SAMPLE_RATE and cclk divide set to 1
+ADC adc(SAMPLE_RATE, 1);
+
+//Functions to write 16 bit audio data and 32 bit headers to files in au format (cf sndRecorder Cookbook)
+void fwrite16(uint16_t v) {
+    uint8_t *b = (uint8_t *)&v;
+
+    fprintf(fp,"%c%c", b[1], b[0]);
+}
+void fwrite32(uint32_t v) {
+    uint8_t *b = (uint8_t *)&v;
+
+    fprintf(fp,"%c%c%c%c", b[3], b[2], b[1], b[0]);
+}
+
+
+
+//Our interrupt handler for audio sampling
+void sample_ADC(int chan, uint32_t value) {
+
+    float s;
+    s = adc.read(p20);
+    int16_t b = (s -2048)*16;
+    Buffer[Counter] = b;
+    Counter += 1;
+    /* bar graph */
+    int g = abs(s-2048);
+    l1 = g > 0.1f*2048;
+    l2 = g > 0.3f*2048;
+    l3 = g > 0.6f*2048;
+    l4 = g > 0.8f*2048;
+}
+
+int main() {
+
+    while (1) {
+        //Prepare for burst mode on all ADC pins and set up interrupt handler (using ADC library from Simon Blandford
+        adc.append(sample_ADC);
+        adc.startmode(0,0);
+        adc.burst(1);
+        adc.setup(p20,1);
+        //introduce a delay as initial waveform has bias whilst decoupling cap charges
+        wait(.4);
+        //start the interrupt and wait for about 4096 samples
+        adc.interrupt_state(p20,1);
+        wait(0.1);
+        //Finsh up - Unset pin 20
+        adc.interrupt_state(p20,0);
+        adc.setup(p20,0);
+        int actual_rate = adc.actual_sample_rate();
+
+        //now lets try mellen fft
+        lcd.background(0x0000FF);
+
+        short mx[MN*2]; // input data 16 bit, 4 byte aligned  x0r,x0i,x1r,x1i,....
+        short my[MN*2]; // output data 16 bit,4 byte aligned  y0r,y0i,y1r,y1i,....
+        float data2[512];
+        for (int i=0;i<MN*2;i++) mx[i]=0;
+
+        for (int i=0;i<MN;i=i+1) {
+            mx[i*2]=Buffer[i];
+        }
+        //FILE* mlog = fopen("/local/mellen.csv","w");
+        //call functions;
+        fftR4(my, mx, MN);
+        for (int i=0; i<MN; i=i+2) {
+            data2[i]= sqrt(float(   (my[i]*my[i])  +(my[i+1]*my[i+1])));
+            //fprintf(mlog, "%d,%f\n", int(actual_rate/MN/2*i),sqrt(float(   (my[i]*my[i])  +(my[i+1]*my[i+1])) )   );
+        }
+        //fclose(mlog);
+
+
+        //Display amplitude on Nokia LCD
+        lcd.cls();
+        for (int i=0; i<128; i++) {
+            data2[i+1] = 20*log10(data2[i+1]);
+            lcd.fill(i, 0, 2, data2[i+1], 0x00FF00);
+        }
+        Counter = 0;
+    }
+}
+
+
+
+
+