Add WaterfallSpectrum example, from Nathaniel Quillin's SuperCon Badge Hack

examples/Analysis/WaterfallSpectrum/WaterfallSpectrum.ino

+/* Waterfall Audio Spectrum Analyzer, adapted from Nathaniel Quillin's
+   award winning (most over the top) Hackaday SuperCon 2015 Badge Hack.
+
+   https://hackaday.io/project/8575-audio-spectrum-analyzer-a-supercon-badge
+   https://github.com/nqbit/superconbadge
+
+   ILI9341 Color TFT Display is used to display spectral data.
+   Two pots on analog A2 and A3 are required to adjust sensitivity.
+
+   Copyright (c) 2015 Nathaniel Quillin
+
+   Permission is hereby granted, free of charge, to any person obtaining
+   a copy of this software and associated documentation files
+   (the "Software"), to deal in the Software without restriction,
+   including without limitation the rights to use, copy, modify, merge,
+   publish, distribute, sublicense, and/or sell copies of the Software,
+   and to permit persons to whom the Software is furnished to do so,
+   subject to the following conditions:
+
+   The above copyright notice and this permission notice shall be
+   included in all copies or substantial portions of the Software.
+
+   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+   EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+   MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+   IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+   CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+   TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+   SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+*/
+
+#include <Audio.h>
+#include <ILI9341_t3.h>
+#include <SD.h>
+#include <SerialFlash.h>
+#include <SPI.h>
+#include <Wire.h>
+
+// ILI9341 Color TFT Display connections
+#define TFT_DC      20
+#define TFT_CS      21
+#define TFT_RST    255  // 255 = unused, connect to 3.3V
+#define TFT_MOSI     7
+#define TFT_SCLK    14
+#define TFT_MISO    12
+
+ILI9341_t3 tft = ILI9341_t3(TFT_CS, TFT_DC, TFT_RST, TFT_MOSI, TFT_SCLK, TFT_MISO);
+
+AudioInputI2S            i2s1;
+AudioOutputI2S           i2s2;
+AudioAnalyzeFFT1024      fft1024_1;
+AudioConnection          patchCord5(i2s1, 0, i2s2, 0);
+AudioConnection          patchCord6(i2s1, 0, i2s2, 1);
+AudioConnection          patchCord7(i2s1, fft1024_1);
+AudioControlSGTL5000     sgtl5000_1;
+
+static int count = 0;
+static uint16_t line_buffer[320];
+static float scale = 10.0;
+static int knob = 0;
+static int vol = 0;
+
+void setup(void) {
+  // Initialize the peripherals.
+  tft.begin();
+  tft.fillScreen(ILI9341_BLACK);
+  tft.setTextColor(ILI9341_YELLOW);
+  tft.setTextSize(2);
+
+  AudioMemory(20);
+  sgtl5000_1.enable();
+  sgtl5000_1.volume(0.5);
+  sgtl5000_1.inputSelect(AUDIO_INPUT_MIC);
+  sgtl5000_1.micGain(36);
+
+  // Uncomment one these to try other window functions
+  // fft1024_1.windowFunction(NULL);
+  // fft1024_1.windowFunction(AudioWindowBartlett1024);
+  // fft1024_1.windowFunction(AudioWindowFlattop1024);
+
+  tft.println("Waterfall Spectrum");
+  tft.println("adapted from");
+  tft.println("Nathaniel Quillin");
+  tft.println("SuperCon Badge Hack");
+  for (int i = 0; i < 100; i++) {
+    tft.setScroll(count++);
+    count = count % 320;
+    delay(12);
+  }
+  tft.setRotation(0);
+}
+
+void loop() {
+  knob = analogRead(A2);
+  vol = analogRead(A3);
+
+  scale = 1024 - knob;
+  sgtl5000_1.micGain((1024 - vol) / 4);
+
+  if (fft1024_1.available()) {
+    for (int i = 0; i < 240; i++) {
+      line_buffer[240 - i - 1] = colorMap(fft1024_1.output[i]);
+    }
+    tft.writeRect(0, count, 240, 1, (uint16_t*) &line_buffer);
+    tft.setScroll(count++);
+    count = count % 320;
+  }
+}
+
+uint16_t colorMap(uint16_t val) {
+  float red;
+  float green;
+  float blue;
+  float temp = val / 65536.0 * scale;
+
+  if (temp < 0.5) {
+    red = 0.0;
+    green = temp * 2;
+    blue = 2 * (0.5 - temp);
+  } else {
+    red = temp;
+    green = (1.0 - temp);
+    blue = 0.0;
+  }
+  return tft.color565(red * 256, green * 256, blue * 256);
+}
+
+