For automotive enthusiasts keen on pushing the boundaries of vehicle customization, delving into DIY car computer projects offers an exciting avenue. While factory Engine Control Units (ECUs) and OBD2 systems provide a robust foundation, platforms like Arduino open up possibilities for bespoke functionalities and enhanced control. This article explores the potential of Arduino in creating a custom car computer, addressing key aspects from sensor integration to control logic.
Understanding the Core Components
Building a DIY car computer with Arduino involves several crucial input and output considerations. To effectively manage vehicle functions, the system needs to accurately perceive various parameters. Let’s break down the essential sensors and control mechanisms:
Detecting Vehicle Standstill
One fundamental aspect is determining when the vehicle is stationary. A common approach involves tapping into the vehicle’s speed sensor. Typically, these sensors are three-wire devices, incorporating a ground, a 5-volt supply, and a signal wire. The Arduino can be programmed to monitor the signal wire for a zero sine wave, indicating no wheel rotation. Alternatively, a simpler method involves setting a low RPM threshold, such as below 1200 RPM, to signify a standstill.
Alt text: Car speed sensor with three wires, commonly used in automotive applications for detecting vehicle speed.
Clutch and Neutral Position Input
For projects requiring gearshift awareness, integrating clutch and neutral position detection is vital. Most vehicles are equipped with a clutch pedal switch, which can serve as a direct input to the Arduino. Similarly, a momentary switch installed on the gear shift lever, specifically triggered in the neutral position, provides neutral gear input. These switches offer straightforward digital signals for the Arduino to process.
Alt text: Close-up of a clutch pedal switch mechanism in a car footwell, illustrating its role in detecting clutch engagement.
Temperature Monitoring
Monitoring temperature can be crucial for various vehicle control applications. While thermistors are a viable option for temperature sensing, simpler on/off temperature sensors, such as a 50°C sensor, can be equally effective for certain tasks. The choice depends on the project’s specific requirements for temperature data granularity.
Alt text: Example of a thermistor temperature sensor, a component that changes resistance based on temperature variations, suitable for Arduino projects.
Engine Running Detection
Ensuring the engine is running before initiating certain actions is a critical safety and operational consideration. Several methods can be employed for engine running detection. One approach involves using a clamp-style inductive pickup, similar to those used with timing lights. By clamping this pickup to a spark plug wire, the Arduino can detect the inductive pulses generated by spark ignition, confirming engine operation.
Alternatively, for diesel engines or simpler gasoline engine setups, monitoring battery voltage fluctuations can be a practical approach. A voltage increase from the resting 12.5V to a charging voltage around 14.4V indicates the engine is running and the alternator is charging. Another method, particularly for crank signal detection, involves tapping into the crank sensor signal wire. The Arduino can be programmed to recognize the square wave signal from the crank sensor, confirming engine rotation.
Alt text: Inductive pickup clamp of a timing light being attached to a spark plug wire to detect engine ignition pulses.
Implementing Control Logic
With sensor inputs in place, the next step involves programming the Arduino to execute desired control logic. A key aspect is differentiating between various clutch states and gear positions to implement functions like engine start/stop control. For instance, the logic could be designed to require clutch depression, followed by neutral gear selection, and then clutch release for engine start. Subsequent engine restarts might then be conditioned only on clutch pedal depression, creating a specific starting sequence.
Fuel Cutoff Implementation
For engine shutdown control, fuel cutoff mechanisms are essential. Diesel engines often employ a fuel cutoff solenoid, which can be intercepted and controlled by the Arduino via a 12V relay. Activating the relay applies voltage to the solenoid, cutting off fuel supply and stopping the engine. For gasoline engines, fuel cutoff can be achieved by interrupting the 12V supply to the fuel pump or by splicing into the fuel pump relay wire and controlling it with the Arduino and a relay.
Alt text: Fuel cutoff solenoid on a diesel engine, a component that can be electronically controlled to stop fuel flow and engine operation.
Conclusion
DIY car computer projects using Arduino offer a powerful platform for customizing vehicle control and adding advanced functionalities. By integrating various sensors and implementing logical control through Arduino programming, enthusiasts can create bespoke systems tailored to their specific needs. While coding may present a learning curve, the wealth of online resources and community support makes these projects increasingly accessible to those eager to explore the realm of automotive electronics.
