Diff: main.cpp

Revision:

0:0c037aff5039

Child:

1:736b34e0f484

diff -r 000000000000 -r 0c037aff5039 main.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Tue Feb 25 17:42:59 2014 +0000
@@ -0,0 +1,347 @@
+// Audio Spectrum Display
+// Copyright 2013 Tony DiCola (tony@tonydicola.com)
+// Code ported from the guide at http://learn.adafruit.com/fft-fun-with-fourier-transforms?view=all
+
+#include "mbed.h"
+#include "NVIC_set_all_priorities.h"
+#include <ctype.h>
+#include "arm_math.h"
+#include "hsi2rgbw_pwm.h"
+
+Serial pc(USBTX, USBRX);
+
+AnalogIn   left(PTC2);
+AnalogIn   right(PTB3);
+
+//#define RGBW_ext // Disable this line when you want to use the KL25Z on-board RGB LED.
+
+#ifndef RGBW_ext
+// HSI to RGB conversion with direct output to PWM channels - on-board RGB LED
+hsi2rgbw_pwm led(LED_RED, LED_GREEN, LED_BLUE);
+#else
+// HSI to RGBW conversion with direct output to external PWM channels - RGBW LED
+hsi2rgbw_pwm led(PTD4, PTA12, PTA4, PTA5); //Red, Green, Blue, White
+#endif
+
+// Dummy ISR for disabling NMI on PTA4 - !! DO NOT REMOVE THIS !!
+// More info at https://mbed.org/questions/1387/How-can-I-access-the-FTFA_FOPT-register-/
+extern "C" void NMI_Handler() {
+    DigitalIn test(PTA4);
+}
+
+
+////////////////////////////////////////////////////////////////////////////////
+// CONFIGURATION
+// These values can be changed to alter the behavior of the spectrum display.
+// KL25Z limitations
+// -----------------
+// - When used without the Spectrogram python script :
+//   When SAMPLE_RATE_HZ = 10000...40000, max allowed FFT_SIZE is 16.
+//   When SAMPLE_RATE_HZ < 9000, FFT can go up to 256 
+// - When used with the Spectrogram python script :
+//   There is a substantial time lag between the music and the screen output.
+//   Max allowed SAMPLE_RATE_HZ is 8000
+//   Max allowed FFT_SIZE is 16
+////////////////////////////////////////////////////////////////////////////////
+
+int SLOWDOWN = 16;                      // Create an optical delay in spectrumLoop - useful when only one RGB led is used.
+                                        // Only active when nonzero.
+                                        // A value >= 1000 and <= 1000 + PIXEL_COUNT fixes the output to a single frequency
+                                        // window = a single color.
+int SAMPLE_RATE_HZ = 40000;             // Sample rate of the audio in hertz.
+float SPECTRUM_MIN_DB = 30.0;           // Audio intensity (in decibels) that maps to low LED brightness.
+float SPECTRUM_MAX_DB = 60.0;           // Audio intensity (in decibels) that maps to high LED brightness.
+int LEDS_ENABLED = 1;                   // Control if the LED's should display the spectrum or not.  1 is true, 0 is false.
+                                        // Useful for turning the LED display on and off with commands from the serial port.
+const int FFT_SIZE = 16;                // Size of the FFT.
+const int PIXEL_COUNT = 8;              // Number of pixels.  You should be able to increase this without
+                                        // any other changes to the program.
+const int MAX_CHARS = 65;               // Max size of the input command buffer
+
+////////////////////////////////////////////////////////////////////////////////
+// INTERNAL STATE
+// These shouldn't be modified unless you know what you're doing.
+////////////////////////////////////////////////////////////////////////////////
+Ticker samplingTimer;
+float samples[FFT_SIZE*2];
+float magnitudes[FFT_SIZE];
+int sampleCounter = 0;
+char commandBuffer[MAX_CHARS];
+float frequencyWindow[PIXEL_COUNT+1];
+float hues[PIXEL_COUNT];
+bool commandRecv = 0;
+////////////////////////////////////////////////////////////////////////////////
+// UTILITY FUNCTIONS
+////////////////////////////////////////////////////////////////////////////////
+
+void rxisr() {
+    char c = pc.getc();
+    // Add any characters that aren't the end of a command (semicolon) to the input buffer.
+    if (c != ';') {
+        c = toupper(c);
+        strncat(commandBuffer, &c, 1);
+    } else {
+        // Parse the command because an end of command token was encountered.
+        commandRecv = 1;
+    }
+}
+
+// Compute the average magnitude of a target frequency window vs. all other frequencies.
+void windowMean(float* magnitudes, int lowBin, int highBin, float* windowMean, float* otherMean)
+{
+    *windowMean = 0;
+    *otherMean = 0;
+    // Notice the first magnitude bin is skipped because it represents the
+    // average power of the signal.
+    for (int i = 1; i < FFT_SIZE/2; ++i) {
+        if (i >= lowBin && i <= highBin) {
+            *windowMean += magnitudes[i];
+        } else {
+            *otherMean += magnitudes[i];
+        }
+    }
+    *windowMean /= (highBin - lowBin) + 1;
+    *otherMean /= (FFT_SIZE / 2 - (highBin - lowBin));
+}
+
+// Convert a frequency to the appropriate FFT bin it will fall within.
+int frequencyToBin(float frequency)
+{
+    float binFrequency = float(SAMPLE_RATE_HZ) / float(FFT_SIZE);
+    return int(frequency / binFrequency);
+}
+
+
+////////////////////////////////////////////////////////////////////////////////
+// SPECTRUM DISPLAY FUNCTIONS
+///////////////////////////////////////////////////////////////////////////////
+
+void spectrumSetup()
+{
+    // Set the frequency window values by evenly dividing the possible frequency
+    // spectrum across the number of neo pixels.
+    float windowSize = (SAMPLE_RATE_HZ / 2.0) / float(PIXEL_COUNT);
+    for (int i = 0; i < PIXEL_COUNT+1; ++i) {
+        frequencyWindow[i] = i*windowSize;
+    }
+    // Evenly spread hues across all pixels.
+    for (int i = 0; i < PIXEL_COUNT; ++i) {
+        hues[i] = 360.0*(float(i)/float(PIXEL_COUNT-1));
+    }
+}
+
+void spectrumLoop()
+{
+    // Update each LED based on the intensity of the audio
+    // in the associated frequency window.
+    static int SLrpt = 0, SLpixcnt = 0;
+    int SLpixend = 0;
+    float intensity, otherMean;
+    if(SLOWDOWN != 0)
+    {
+        if(SLOWDOWN >= 1000)
+        {
+            if(SLOWDOWN <= (1000 + PIXEL_COUNT-1))
+            {
+                SLpixcnt = SLOWDOWN - 1000;
+                SLrpt = 0;
+                SLpixend = SLpixcnt + 1;
+            }
+            else
+                SLOWDOWN = 0;
+        }
+        else
+        {
+            SLrpt++;
+            if (SLrpt >= SLOWDOWN)
+            {
+                SLrpt = 0;
+                SLpixcnt = SLpixcnt < PIXEL_COUNT-1 ? ++SLpixcnt : 0;
+            }
+            SLpixend = SLpixcnt + 1;
+        }
+    }
+    else
+    {
+        SLpixcnt = 0;
+        SLrpt = 0;
+        SLpixend = PIXEL_COUNT;
+    }
+    for (int i = SLpixcnt; i < SLpixend; ++i) {
+        windowMean(magnitudes,
+                   frequencyToBin(frequencyWindow[i]),
+                   frequencyToBin(frequencyWindow[i+1]),
+                   &intensity,
+                   &otherMean);
+        // Convert intensity to decibels.
+        intensity = 20.0*log10(intensity);
+        // Scale the intensity and clamp between 0 and 1.0.
+        intensity -= SPECTRUM_MIN_DB;
+        intensity = intensity < 0.0 ? 0.0 : intensity;
+        intensity /= (SPECTRUM_MAX_DB-SPECTRUM_MIN_DB);
+        intensity = intensity > 1.0 ? 1.0 : intensity;
+        led.hsi2rgbw(hues[i], 1.0, intensity);
+    }
+}
+
+
+////////////////////////////////////////////////////////////////////////////////
+// SAMPLING FUNCTIONS
+////////////////////////////////////////////////////////////////////////////////
+
+void samplingCallback()
+{
+    // Read from the ADC and store the sample data
+    samples[sampleCounter] = 1023 * ((left + right)/2);
+    // Complex FFT functions require a coefficient for the imaginary part of the input.
+    // Since we only have real data, set this coefficient to zero.
+    samples[sampleCounter+1] = 0.0;
+    // Update sample buffer position and stop after the buffer is filled
+    sampleCounter += 2;
+    if (sampleCounter >= FFT_SIZE*2) {
+        samplingTimer.detach();
+    }
+}
+
+void samplingBegin()
+{
+    // Reset sample buffer position and start callback at necessary rate.
+    sampleCounter = 0;
+    samplingTimer.attach_us(&samplingCallback, 1000000/SAMPLE_RATE_HZ);
+}
+
+bool samplingIsDone()
+{
+    return sampleCounter >= FFT_SIZE*2;
+}
+
+
+////////////////////////////////////////////////////////////////////////////////
+// COMMAND PARSING FUNCTIONS
+// These functions allow parsing simple commands input on the serial port.
+// Commands allow reading and writing variables that control the device.
+//
+// All commands must end with a semicolon character.
+//
+// Example commands are:
+// GET SAMPLE_RATE_HZ;
+// - Get the sample rate of the device.
+// SET SAMPLE_RATE_HZ 400;
+// - Set the sample rate of the device to 400 hertz.
+//
+////////////////////////////////////////////////////////////////////////////////
+
+void parseCommand(char* command)
+{
+    if (strcmp(command, "GET MAGNITUDES") == 0) {
+        for (int i = 0; i < FFT_SIZE; ++i) {
+            printf("%f\r\n", magnitudes[i]);
+        }
+    } else if (strcmp(command, "GET SAMPLES") == 0) {
+        for (int i = 0; i < FFT_SIZE*2; i+=2) {
+            printf("%f\r\n", samples[i]);
+        }
+    } else if (strcmp(command, "GET FFT_SIZE") == 0) {
+        printf("%d\r\n", FFT_SIZE);
+    } else if (strcmp(command, "GET SAMPLE_RATE_HZ") == 0) {
+        printf("%d\r\n", SAMPLE_RATE_HZ);
+    } else if (strstr(command, "SET SAMPLE_RATE_HZ") != NULL) {
+        SAMPLE_RATE_HZ = (typeof(SAMPLE_RATE_HZ)) atof(command+(sizeof("SET SAMPLE_RATE_HZ")-1));
+    } else if (strcmp(command, "GET LEDS_ENABLED") == 0) {
+        printf("%d\r\n", LEDS_ENABLED);
+    } else if (strstr(command, "SET LEDS_ENABLED") != NULL) {
+        LEDS_ENABLED = (typeof(LEDS_ENABLED)) atof(command+(sizeof("SET LEDS_ENABLED")-1));
+    } else if (strcmp(command, "GET SPECTRUM_MIN_DB") == 0) {
+        printf("%f\r\n", SPECTRUM_MIN_DB);
+    } else if (strstr(command, "SET SPECTRUM_MIN_DB") != NULL) {
+        SPECTRUM_MIN_DB = (typeof(SPECTRUM_MIN_DB)) atof(command+(sizeof("SET SPECTRUM_MIN_DB")-1));
+    } else if (strcmp(command, "GET SPECTRUM_MAX_DB") == 0) {
+        printf("%f\r\n", SPECTRUM_MAX_DB);
+    } else if (strstr(command, "SET SPECTRUM_MAX_DB") != NULL) {
+        SPECTRUM_MAX_DB = (typeof(SPECTRUM_MAX_DB)) atof(command+(sizeof("SET SPECTRUM_MAX_DB")-1));
+    } else if (strcmp(command, "GET SLOWDOWN") == 0) {
+        printf("%d\r\n", SLOWDOWN);
+    } else if (strstr(command, "SET SLOWDOWN") != NULL) {
+        SLOWDOWN = (typeof(SLOWDOWN)) atoi(command+(sizeof("SET SLOWDOWN")-1));
+    }
+
+    // Update spectrum display values if sample rate was changed.
+    if (strstr(command, "SET SAMPLE_RATE_HZ ") != NULL) {
+        spectrumSetup();
+    }
+
+    // Turn off the LEDs if the state changed.
+    if (LEDS_ENABLED == 0) {
+    }
+}
+
+void parserLoop()
+{
+    // Process any incoming characters from the serial port
+    while (pc.readable()) {
+        char c = pc.getc();
+        // Add any characters that aren't the end of a command (semicolon) to the input buffer.
+        if (c != ';') {
+            c = toupper(c);
+            strncat(commandBuffer, &c, 1);
+        } else {
+            // Parse the command because an end of command token was encountered.
+            parseCommand(commandBuffer);
+            // Clear the input buffer
+            memset(commandBuffer, 0, sizeof(commandBuffer));
+        }
+    }
+}
+
+////////////////////////////////////////////////////////////////////////////////
+// MAIN FUNCTION
+////////////////////////////////////////////////////////////////////////////////
+
+int main()
+{
+    NVIC_set_all_irq_priorities(1);
+    NVIC_SetPriority(UART0_IRQn, 0);
+    // Set up serial port.
+    pc.baud (38400);
+    pc.attach(&rxisr);
+#ifndef RGBW_ext
+    led.invertpwm(1); //On-board KL25Z RGB LED uses common anode.
+#endif 
+    // Clear the input command buffer
+    memset(commandBuffer, 0, sizeof(commandBuffer));
+
+    // Initialize spectrum display
+    spectrumSetup();
+
+    // Begin sampling audio
+    samplingBegin();
+
+    while(1) {
+        // Calculate FFT if a full sample is available.
+        if (samplingIsDone()) {
+            // Run FFT on sample data.
+            arm_cfft_radix4_instance_f32 fft_inst;
+            arm_cfft_radix4_init_f32(&fft_inst, FFT_SIZE, 0, 1);
+            arm_cfft_radix4_f32(&fft_inst, samples);
+            // Calculate magnitude of complex numbers output by the FFT.
+            arm_cmplx_mag_f32(samples, magnitudes, FFT_SIZE);
+
+            if (LEDS_ENABLED == 1) {
+                spectrumLoop();
+            }
+
+            // Restart audio sampling.
+            samplingBegin();
+        }
+
+        // Parse any pending commands.
+        if(commandRecv) {
+//            pc.attach(NULL);
+            parseCommand(commandBuffer);
+            commandRecv = 0;
+            // Clear the input buffer
+            memset(commandBuffer, 0, sizeof(commandBuffer));
+//            pc.attach(&rxisr);
+        }
+    }
+}