📊 ESP32 Real-Time FFT + Waterfall Visualizer This project implements a real-time frequency spectrum analyzer using FFT (Fast Fourier Transform) and a waterfall display on an ESP32 with an ILI9341 TFT screen. It captures audio or analog signals through the internal ADC, performs spectral analysis, and visualizes the result graphically.
🔧 Requirements ESP32
ILI9341 TFT display
Arduino libraries:
arduinoFFT
Adafruit_ILI9341
Adafruit_GFX
📐 Specifications Sampling rate: 512 samples at 44 kHz
FFT resolution: 512-point FFT (covers up to 22 kHz)
Display outputs:
Real-time FFT bar graph
Waterfall (scrolling color-based frequency map)
Color mapping: blue → cyan → yellow → red, based on signal intensity
Adjustable gain: via fftGain_dB
Optional noise subtraction (simple spectral background filtering)
ADC sampling via analogRead(), synchronized with micros() timer
📌 Default Pinout Signal ESP32 Pin Description ADC_IN GPIO35 Analog input (ADC1_CH8) DAC_OUT GPIO25 DAC output (optional use) TFT_CS GPIO15 Chip Select for TFT TFT_DC GPIO2 Data/Command for TFT TFT_RST GPIO4 TFT Reset
🖥️ Display Interface FFT view: vertical green bars representing signal magnitude
Waterfall view: scrolling spectral heatmap with colors for intensity
Colors are calculated with the intensityToColor() function for a smooth gradient.
🔍 Key Functions captureSamples() — Samples analog data at precise intervals
drawFFTLine() — Draws vertical spectrum bars on screen
drawWaterfallLine() — Draws and scrolls new waterfall lines
intensityToColor() — Maps signal intensity to RGB color
smoothMagnitude() — Applies simple smoothing to FFT bins
🧪 Options & Features Set useNoiseSubtraction = true to enable simple background noise filtering.
Adjust fftGain_dB to scale the FFT intensity (useful for visual tuning).
📷 Demo (Insert a GIF or image of the waterfall + FFT display here)
📁 Related Projects If you have other similar versions (e.g., DMA-accelerated, I2S ADC, ILI9488 support), you can reuse this structure and update:
Sampling method (analogRead() vs I2S)
Screen resolution and type
FFT size or frequency range