SmartCruiseControl

SmartCruiseControl is an embedded ESP32 project that implements cruise control using CAN Bus data, with vehicle state monitoring and ELM327 command emulation for the Smart forfour 454 car

Description

The software runs on an ESP32 using the Arduino framework and focuses on:

• Reading CAN Bus frames from a Smart vehicle.
• Estimating speed, RPM, distance, fuel level, and other critical vehicle parameters.
• Cruise control with PID, button-based enable/disable, and throttle override handling.
• Basic ELM327 emulation for OBD-II 01xx and 22xx command responses.
• Cruise control status indication using an LED.

Key features

• CAN Bus listen-only mode (TWAI_MODE_LISTEN_ONLY) at 500 kbps.
• Support for reading the following key CAN IDs:
  • 0x09E - total distance
  • 0x200 - speed
  • 0x208 - brake intensity and extra speed data
  • 0x210 - accelerator pedal position
  • 0x308 - engine RPM
  • 0x408 - fuel level
  • 0x416 - battery voltage
  • 0x423 - door status
  • 0x608 - refrigerant temperature and fuel rate
• Cruise control state machine with:
  • STATE_OFF
  • STATE_ACTIVE
  • STATE_OVERRIDE
• ELM327 interface over Serial with basic AT, 01, and 22 command handling.

Project structure

• platformio.ini - PlatformIO configuration for ESP32.
• src/main.cpp - main entry point and FreeRTOS task setup.
• include/ - constants, state definitions, and shared headers.
• lib/ - modular libraries:
  • can/ - CAN bus reading and decoding.
  • cruise_control/ - cruise control logic.
  • elm327/ - ELM327 emulation and OBD response handling.
  • fuel_range_estimator/ - fuel range estimation.
  • indicator_led/ - PWM LED status indicator.
  • pid_controller/ - generic PID controller.
  • speed_estimator/ - speed estimation from CAN frames.
  • throttle/ - throttle output and override management.
  • buttons/ - analog button reading and cruise control button detection.
• doc/ - CAN Bus reverse engineering documentation.
• test/ - PlatformIO testing notes and setup.

Requirements

See requirements.md file for required software and hardware

How to build

See how-to-build.md file to build software and hardware

Usage

• The system starts by creating FreeRTOS tasks for CAN reception, CAN processing, and ELM327 emulation.
• The indicator LED shows cruise control status:
  • off = cruise control disabled
  • full brightness = cruise control active
  • fading = throttle override active
• Cruise control buttons support SET, RESUME, and CANCEL.
• Pressing the accelerator while cruise control is active transitions the system to STATE_OVERRIDE.

Notes

• The project is designed for the Smart Forfour 454 (2006) model, as described at the beginning of doc/CAN bus reverse engineering.md.
• With the necessary modifications, it could be adapted to other vehicles that use CAN Bus, electronic throttle, and physical brake/clutch switches.
• The implementation is based on CAN data documented in doc/CAN bus reverse engineering.md.
• The ESP32 pinout reference image is available at doc/ESP32 pinout.png and is used under Creative Commons BY-NC-ND via www.mischianti.org.

Inspirations

This project was inspired by:

• esp32_cruise_control
• autocruise
• esp32-elm327-cruise-control

License

See the LICENSE file for the project license terms.