How to Use RejsaCAN_OBD: Examples, Pinouts, and Specs

The RejsaCAN_OBD is a diagnostic interface designed for vehicles that utilize the CAN (Controller Area Network) protocol. It enables communication with the onboard computer systems, allowing users to read diagnostic trouble codes (DTCs), monitor real-time data, and analyze vehicle performance. This component is ideal for automotive diagnostics, performance tuning, and real-time data logging.

• Reading and clearing diagnostic trouble codes (DTCs)
• Monitoring real-time vehicle data (e.g., engine RPM, speed, temperature)
• Performance tuning and optimization
• Data logging for research and development
• Integration with microcontrollers (e.g., Arduino) for custom automotive projects

The RejsaCAN_OBD is designed to interface with the OBD-II port of vehicles and supports the CAN protocol. Below are the key technical details:

1. Power the Module: Connect the VCC pin to a 5V power source and the GND pin to ground.
2. Connect to Microcontroller:
   • Connect the RX pin of the RejsaCAN_OBD to the TX pin of your microcontroller.
   • Connect the TX pin of the RejsaCAN_OBD to the RX pin of your microcontroller.
3. Connect to Vehicle OBD-II Port:
   • Connect the CAN_H pin to the CAN high line of the vehicle's OBD-II port.
   • Connect the CAN_L pin to the CAN low line of the vehicle's OBD-II port.
4. Configure Communication: Set the baud rate of your microcontroller's UART to match the RejsaCAN_OBD's default baud rate (500 kbps, unless reconfigured).
5. Send and Receive Data: Use serial commands to send requests and receive data from the vehicle's onboard systems.

• Ensure the vehicle's ignition is turned on before attempting to communicate with the OBD-II system.
• Use proper termination resistors (typically 120 ohms) on the CAN bus if required by your setup.
• Avoid connecting the module to vehicles that do not support the CAN protocol.
• Double-check all connections to prevent damage to the module or the vehicle's electronics.

Below is an example of how to use the RejsaCAN_OBD with an Arduino UNO to read data from a vehicle:

#include <SoftwareSerial.h>

// Define RX and TX pins for SoftwareSerial
SoftwareSerial RejsaCAN(10, 11); // RX = pin 10, TX = pin 11

void setup() {
  Serial.begin(9600); // Initialize Serial Monitor
  RejsaCAN.begin(500000); // Initialize RejsaCAN_OBD at 500 kbps

  Serial.println("RejsaCAN_OBD Initialized");
  delay(1000);
}

void loop() {
  // Send a request to the vehicle (e.g., engine RPM)
  RejsaCAN.println("010C"); // OBD-II PID for engine RPM

  // Wait for a response
  if (RejsaCAN.available()) {
    String response = "";
    while (RejsaCAN.available()) {
      char c = RejsaCAN.read();
      response += c;
    }
    Serial.println("Response: " + response);
  }

  delay(1000); // Wait 1 second before sending the next request
}

• Replace 010C with the appropriate OBD-II PID for the data you want to retrieve.
• Ensure the SoftwareSerial library is installed and configured correctly.
• Use the Serial Monitor to view the responses from the RejsaCAN_OBD.

1. No Response from the Module:

   • Ensure the vehicle's ignition is turned on.
   • Verify that the CAN_H and CAN_L connections are correct.
   • Check the baud rate configuration of your microcontroller.

2. Incorrect or Garbled Data:

   • Confirm that the UART baud rate matches the RejsaCAN_OBD's baud rate.
   • Check for loose or faulty connections.

3. Module Not Powering On:

   • Verify that the VCC pin is receiving 5V.
   • Check the ground connection.

4. Vehicle Not Responding:

   • Ensure the vehicle supports the CAN protocol.
   • Verify that the OBD-II port is functional.

Q: Can the RejsaCAN_OBD be used with vehicles that do not support CAN?
A: No, the RejsaCAN_OBD is specifically designed for vehicles that utilize the CAN protocol.

Q: How do I know if my vehicle supports the CAN protocol?
A: Most vehicles manufactured after 2008 support the CAN protocol. Check your vehicle's manual or OBD-II port specifications for confirmation.

Q: Can I use the RejsaCAN_OBD with other microcontrollers besides Arduino?
A: Yes, the RejsaCAN_OBD can be used with any microcontroller that supports UART communication, such as ESP32, STM32, or Raspberry Pi.

Q: Is it safe to leave the module connected to the vehicle?
A: Yes, but it is recommended to disconnect the module when not in use to prevent unnecessary power drain.

Q: How do I clear diagnostic trouble codes (DTCs)?
A: Send the OBD-II command 04 to clear all stored DTCs. Ensure you understand the implications of clearing codes before proceeding.