ESP32-DDS-Signal-Generator

Overview

The ESP32 "Advanced" DDS Signal Generator is a precision waveform generator built around the ESP32 microcontroller. It implements Direct Digital Synthesis (DDS) techniques to produce stable, configurable waveforms with professional-grade features. This project combines hardware design with robust software architecture to create a versatile instrument suitable for electronics testing, education, and embedded systems development.

Key Features

• Frequency Range: 0.01Hz to 5MHz with 0.61Hz resolution at 40kHz sample rate
• Waveforms: Sine, Square, Triangle, Sawtooth (256-point precision)
• Control Interfaces:
  • Rotary encoder with push-button for local control
  • Web-based interface via WiFi AP (192.168.4.1)
  • OLED display for real-time parameter monitoring
• Signal Quality:
  • Low-pass filtering with configurable cutoff frequency
  • DC offset calibration
  • Output buffering with LM358 op-amp
• Professional Architecture:
  • Modular firmware design with separation of concerns
  • Hardware abstraction layer
  • Timer-driven sampling for precise timing
  • Error handling and input validation

Hardware Requirements

Component	Specification	Notes
ESP32	ESP32-WROOM-32	DevKitC-V4 recommended
DDS Module	AD9833	With 25MHz crystal
Display	0.96" OLED	I2C SSD1306 128x64
Rotary Encoder	EC11	With push-button
Op-Amp	LM358	For output buffering
Voltage Regulator	LM1117-3.3	Clean power for analog section
Passive Components	Capacitors, Resistors	See BOM for details

Setup Instructions

1. Hardware Assembly

1. Connect components according to the schematic in docs/setup_guide.md
2. Ensure proper power filtering near analog components
3. Verify all connections with multimeter before powering

2. Software Installation

# Clone repository
git clone https://github.com/Customize5773/ESP32-DDS-Signal-Generator.git

# Install required tools
pip install esptool adafruit-ampy

# Deploy firmware
ampy --port /dev/ttyUSB0 put firmware

3. Initial Configuration

1. Power on the device
2. Connect to WiFi AP: DDS_Generator (password: generate123)
3. Access web interface at 192.168.4.1
4. Verify 1kHz sine wave output with oscilloscope

Usage Examples

Basic Operation

from dds_engine import DDSEngine
from frequency_controller import FrequencyController
from dac_driver import DACDriver

# Initialize components
dac = DACDriver(pin=25)
freq_ctrl = FrequencyController(sample_rate=40000)
dds = DDSEngine(dac, freq_ctrl)

# Start output
dds.start()
freq_ctrl.set_frequency(1000)  # 1kHz

Changing Waveforms

# Available waveforms: 'sine', 'square', 'triangle', 'sawtooth'
dds.set_waveform('triangle')

Frequency Sweep

import time

for freq in range(100, 5001, 100):  # 100Hz to 5kHz in 100Hz steps
    freq_ctrl.set_frequency(freq)
    time.sleep(0.5)  # Dwell at each frequency

Web Interface Controls

<!-- Example web control -->
<button onclick="fetch('/set?freq=440')">440Hz Tone</button>
<button onclick="fetch('/wave?type=square')">Square Wave</button>

Performance Specifications

Parameter	Value	Notes
Frequency Range	0.01Hz - 5MHz	Limited by ESP32 processing
Frequency Resolution	0.61Hz	At 40kHz sample rate
Amplitude Range	0-3.3V	Configurable via output stage
THD (1kHz sine)	<1%	With proper filtering
Phase Noise	-70dBc/Hz @ 1kHz offset	At 1MHz output
Sample Rate	Up to 40kHz	MicroPython limitation

Calibration

Refer to /docs/calibration_procedure.md for:

• Frequency accuracy calibration
• DC offset compensation
• Amplitude flatness correction
• Temperature compensation (advanced)

License

This project is licensed under the MIT License - see the LICENSE file for details.

Acknowledgements

• ESP32 hardware abstraction based on MicroPython
• DDS algorithm inspiration from Analog Devices AD9833 documentation
• Web interface using MicroPython's AsyncWebServer implementation

Inspiration

• AZDelivery