How to Use Arduino Can-Bus Shield: Examples, Pinouts, and Specs

The Arduino CAN-Bus Shield (Manufacturer Part ID: DEV-10039) by SparkFun Electronics is a versatile shield designed to enable Arduino boards to communicate using the Controller Area Network (CAN) protocol. CAN is a robust communication standard widely used in automotive, industrial, and embedded systems for reliable data exchange between microcontrollers and devices.

This shield is ideal for applications such as:

• Automotive diagnostics and data logging
• Industrial automation and control systems
• Robotics and sensor networks
• Communication between multiple microcontrollers

The shield is built around the MCP2515 CAN controller and MCP2551 CAN transceiver, providing a complete solution for CAN communication.

1. Attach the Shield: Plug the CAN-Bus Shield onto your Arduino board, ensuring proper alignment of the pins.
2. Connect to the CAN Bus:
   • Use the CANH and CANL terminals to connect the shield to the CAN bus.
   • Ensure proper termination resistors (typically 120Ω) are present at both ends of the CAN bus.
3. Power the System: Power the Arduino board via USB or an external power source. The shield will draw power from the Arduino.
4. Install Required Libraries:
   • Download and install the MCP_CAN library from the Arduino Library Manager or GitHub.
5. Write and Upload Code:
   • Use the example code below to initialize the CAN bus and send/receive messages.

#include <mcp_can.h>
#include <SPI.h>

// Define the SPI Chip Select pin for the CAN controller
#define CAN_CS 10

// Create an instance of the MCP_CAN class
MCP_CAN CAN(CAN_CS);

void setup() {
  Serial.begin(115200); // Initialize serial communication for debugging
  while (!Serial);

  // Initialize the CAN controller at 500 kbps
  if (CAN.begin(MCP_ANY, 500000, MCP_8MHZ) == CAN_OK) {
    Serial.println("CAN-Bus Shield initialized successfully!");
  } else {
    Serial.println("Error initializing CAN-Bus Shield. Check connections.");
    while (1);
  }

  // Set the CAN controller to normal mode
  CAN.setMode(MCP_NORMAL);
  Serial.println("CAN-Bus Shield is now in normal mode.");
}

void loop() {
  // Example: Send a CAN message with ID 0x100 and 8 bytes of data
  byte data[8] = {0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08};
  if (CAN.sendMsgBuf(0x100, 0, 8, data) == CAN_OK) {
    Serial.println("Message sent successfully!");
  } else {
    Serial.println("Error sending message.");
  }

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

• Termination Resistors: Ensure the CAN bus is properly terminated with 120Ω resistors at both ends to prevent signal reflections.
• Baud Rate Matching: All devices on the CAN bus must operate at the same baud rate.
• Power Supply: Verify that the Arduino board can supply sufficient current for the shield and any connected peripherals.
• Shield Stacking: If stacking multiple shields, ensure no pin conflicts occur.

1. CAN-Bus Shield Not Initializing:

   • Verify the SPI connections (D10, D11, D12, D13) are properly aligned.
   • Check the baud rate configuration in the code. It must match the CAN bus baud rate.
   • Ensure the MCP_CAN library is correctly installed.

2. No Communication on the CAN Bus:

   • Confirm the CANH and CANL lines are correctly connected to the bus.
   • Check for proper termination resistors (120Ω) at both ends of the CAN bus.
   • Ensure all devices on the bus are powered and operational.

3. Error Sending or Receiving Messages:

   • Verify the message ID and data length are correctly configured in the code.
   • Check for electrical noise or interference on the CAN bus.

Q: Can I use this shield with Arduino boards other than the UNO?
A: Yes, the shield is compatible with most Arduino boards that use the standard form factor, such as the Arduino Mega and Leonardo. However, ensure the SPI pins are correctly mapped.

Q: What is the maximum cable length for the CAN bus?
A: The maximum length depends on the baud rate. For example, at 500 kbps, the maximum recommended length is approximately 100 meters.

Q: Can I use this shield for OBD-II diagnostics?
A: Yes, the shield can be used for OBD-II applications, but you may need additional software or libraries to interpret OBD-II data.

This documentation provides a comprehensive guide to using the SparkFun Arduino CAN-Bus Shield (DEV-10039). By following the instructions and best practices outlined above, you can successfully integrate CAN communication into your projects.