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⚡ Quick Start - VR Simulator

Start here if you're new to the project.

5-Minute Project Overview

The VR Simulator is an ESP32 firmware that generates realistic automotive variable reluctance crank sensor signals. It outputs authentic Subaru 36-2-2-2 waveforms that can be used for ECU testing, signal conditioning validation, or sensor simulation.

Architecture Diagram

┌─────────────────────────────────────────────────────┐
│  ESP32 VR Simulator                                 │
├─────────────────────────────────────────────────────┤
│                                                     │
│  GPIO4 (PWM Input)  ──→  Frequency Detector        │
│                           ↓                         │
│                      Waveform Generator             │
│                           ↓                         │
│  GPIO25 (VR+) ◄──────── DMA Pipeline ──→ GPIO26    │
│                       (48 kHz, 8-bit)   (VR-)       │
│                                                     │
│  UART0 ──→ Serial Console (115200 baud)            │
└─────────────────────────────────────────────────────┘
        

How-To: Building and Running

Prerequisites

• PlatformIO CLI or VSCode with PlatformIO extension
• ESP32 development board (ESP32-DEVKITC-32)
• USB cable for programming

Build Steps

1. Clone or download the project
2. Open a terminal in the project root
3. Run: pio run
4. Connect your ESP32 via USB
5. Run: pio run -t upload

Monitor Output

pio device monitor --baud 115200

You should see RPM updates every second:

[FREQ] 50.00 Hz | RPM: 1500
[FREQ] 50.00 Hz | RPM: 1500
[FREQ] 50.00 Hz | RPM: 1500

Common Tasks

View the Waveform

Connect an oscilloscope to GPIO25 (VR+) and GPIO26 (VR-) to see the differential signals. The waveform shows realistic sinusoidal teeth with compression-based modulation.

Change the RPM

Connect a PWM signal generator to GPIO4:

• 50 Hz → 1500 RPM
• 100 Hz → 3000 RPM
• 150 Hz → 4500 RPM

The simulator will automatically regenerate the waveform to match the input frequency.

Generate Test Plots

python plot_vr_signals.py

Creates a comparison plot of signals at 1500 and 3000 RPM.

Troubleshooting Quick Reference

Problem	Solution
Build fails with "esp-idf not found"	Run pio run -c -e esp32 to rebuild everything
No signal on GPIO25/26	Check oscilloscope ground connection and ESP32 power
RPM not updating from GPIO4	Verify PWM frequency is 20-200 Hz and signal is 3.3V compatible
Serial monitor shows garbage	Ensure baud rate is set to 115200

What's Next?

Once you have the basic firmware running:

• Understand the architecture → Read Development Guide
• Modify the code → See "C Firmware Architecture" in the Dev Guide
• Release a new version → Follow Release Checklist