DIY Arduino OBD2 Bluetooth Car Coolant Temperature Display

Are you fascinated by your car’s inner workings and eager to visualize real-time data? This project will guide you through creating a simple yet effective coolant temperature display for your car using readily available and budget-friendly components. By tapping into your car’s On-Board Diagnostics (OBD2) system via Bluetooth and an Arduino microcontroller, you can access and display crucial engine data right in front of you. This guide is perfect for hobbyists, car enthusiasts, and anyone curious about exploring the possibilities of Arduino Obd2 Bluetooth integration for vehicle diagnostics and monitoring.

Parts You’ll Need to Get Started

To embark on this exciting project, gather these essential components:

• ELM327 Bluetooth OBD2 Adapter: This is your gateway to your car’s data. It interfaces with your vehicle’s OBD2 port and transmits data wirelessly via Bluetooth. These adapters are widely available online for around $5.
• Arduino Uno Microcontroller: The brain of your project. The Arduino will receive data from the ELM327 adapter, process it, and display it on the LCD. An Arduino Uno can be obtained for approximately $5.
• HC-05 Bluetooth Module: This module enables Bluetooth communication between the ELM327 adapter and your Arduino. It’s a cost-effective way to establish a wireless data link and can be found for around $5.
• LCD I2C Display: This display will show the coolant temperature readings. The I2C interface simplifies wiring, requiring only two data lines. These displays are also typically priced around $5.

Wiring and Connections

Let’s connect the components to bring your coolant temperature display to life:

Arduino Uno Connections

• HC-05 Bluetooth Module: Connect the HC-05 TX pin to the Arduino RX pin and the HC-05 RX pin to the Arduino TX pin. Ensure you also connect the 5V and GND pins of the HC-05 to the Arduino’s power and ground.
• LCD I2C Display: Connect the LCD I2C module’s SCL pin to the Arduino’s SCL pin (A5 on Uno) and the SDA pin to the Arduino’s SDA pin (A4 on Uno). Power the LCD by connecting its VCC and GND pins to the Arduino’s 5V and GND respectively.

HC-05 Bluetooth Module Configuration

To ensure seamless communication, the HC-05 module needs to be configured as the Master, connecting to the ELM327 (which acts as the Slave).

• Entering AT Command Mode: To configure the HC-05, you’ll need to enter AT command mode. Typically, this involves holding down a button on the module while powering it up. The LED on the HC-05 should blink slowly (around every 2 seconds) indicating AT command mode.

• Using Serial Monitor: Open the Arduino Serial Monitor or a similar serial communication program. Configure it to the correct COM port and set the baud rate to 38400 (or the default baud rate of your HC-05 module).

• AT Command Setup: Enter the following AT commands one by one, pressing Enter after each command. Replace "1234,56,789c72" with the actual Bluetooth address of your ELM327 adapter. You can usually find this address in the documentation that came with your ELM327 or by using a Bluetooth scanning app.

  AT+RESET
  AT+ORGL
  AT+ROLE=1
  AT+CMODE=0
  AT+BIND=1234,56,789c72
  AT+INIT
  AT+PAIR=1234,56,789c72,20
  AT+LINK=1234,56,789c72

  Important Note: Disconnect the HC-05 module from the Arduino’s TX and RX pins while uploading code to the Arduino to avoid conflicts.

LCD I2C Display Setup

For the LCD I2C display to function correctly, you’ll need to include the necessary libraries in your Arduino IDE.

• Library Installation: Ensure you have the Wire.h and LiquidCrystal_I2C.h libraries installed. Wire.h is often included by default, but you may need to install LiquidCrystal_I2C.h through the Arduino Library Manager (Sketch > Include Library > Manage Libraries…).

• Code Initialization: In your Arduino code, you’ll need to initialize the LCD object with the correct I2C address. The address 0x3F is common, but it might be different for your specific LCD module. You can use an I2C scanner sketch to determine the correct address if needed.

  #include <Wire.h>
  #include <LiquidCrystal_I2C.h>
  
  LiquidCrystal_I2C lcd(0x3F, 16, 2); // Adjust address if needed
  
  void setup() {
    lcd.init();
    lcd.backlight();
    lcd.print("Coolant Temp:");
  }
  
  void loop() {
    // ... Your code to read OBD2 data and display temperature ...
  }

With these steps completed, you’re well on your way to creating a functional arduino obd2 bluetooth coolant temperature display. The next step involves writing the Arduino code to communicate with the ELM327 adapter, request coolant temperature data, and display it on the LCD. This project provides a fantastic foundation for further exploration into car diagnostics and data visualization using Arduino and OBD2.