The CAN Bus Shield by SEEED is an expansion board designed to enable Arduino boards to communicate over a Controller Area Network (CAN). This shield is particularly useful for automotive and industrial applications where multiple microcontrollers need to communicate with each other efficiently without a host computer.
Common applications include:
Automotive diagnostics
Industrial automation systems
Robotics control systems
Data logging from various sensors
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This circuit features an Arduino Sensor Shield v5.0 interfaced with an I2C LCD Display and an HC-05 Bluetooth Module. The LCD Display is connected for power, ground, and I2C communication, allowing it to display data or messages. The HC-05 Bluetooth Module is wired for serial communication with the Arduino Sensor Shield, enabling wireless data exchange with other Bluetooth-enabled devices.
This circuit is designed to control two GM25 DC motors using a ZK-BM1 10A motor driver, which is managed by a NANO Shield Board. The NANO Shield Board receives input signals from an R6FG receiver and is powered by an 11.1V LiPo battery.
This circuit is an OBD-II vehicle diagnostic interface that uses an Arduino Nano to communicate with a vehicle's CAN bus via an MCP2515 CAN controller. It includes a 7805 voltage regulator to step down the vehicle's 12V supply to 5V, powering the Arduino and other components, and a 1.44-inch TFT display for visual output. A pushbutton is also included for user interaction.
This circuit is designed for robotic control, featuring a TC275 microcontroller setup for processing inputs and outputs, an Arduino Motor Shield to drive a DC motor with encoder feedback and a micro servo, and an HC-SR04 Ultrasonic Sensor for distance sensing. The system is likely used for tasks such as navigation, object avoidance, or precise movement control in a robotic application.
Standard (11 bit) and Extended (29 bit) Data and Remote Frames
Pin Configuration and Descriptions
Pin Number
Function
Description
D2
INT
Interrupt pin, signals the Arduino of incoming messages
D9
CS
Chip Select for SPI communication with MCP2515
D10
Not Connected
Reserved for future use
D11
MOSI
SPI communication with MCP2515
D12
MISO
SPI communication with MCP2515
D13
SCK
SPI Clock
GND
Ground
Ground connection
VCC
Power Supply
5V power supply from the Arduino
Usage Instructions
Connecting the Shield to an Arduino
Power off your Arduino board.
Align the shield's pins with the corresponding headers on the Arduino.
Gently press down until the shield is firmly seated on the Arduino.
Initializing the CAN Bus Shield
Before using the shield, you need to initialize the CAN controller and set the desired baud rate for communication. Here's an example of how to do this using the MCP_CAN library:
#include <mcp_can.h>
#include <SPI.h>
// The SPI Chip Select pin for the CAN controller
const int SPI_CS_PIN = 9;
MCP_CAN CAN(SPI_CS_PIN); // Set CS pin for CAN controller
void setup() {
Serial.begin(115200);
// Initialize CAN bus at 500 kbps
if (CAN_OK == CAN.begin(CAN_500KBPS)) {
Serial.println("CAN Bus Shield initialized at 500 kbps.");
} else {
Serial.println("CAN Bus Shield initialization failed.");
}
}
void loop() {
// Code to send and receive data goes here
}
Sending CAN Messages
To send data over the CAN bus, you can use the sendMsgBuf function provided by the MCP_CAN library:
unsigned char message[8] = {0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07};
// Send a standard frame with ID 0x100 and length of 8 bytes
CAN.sendMsgBuf(0x100, 0, 8, message);
Receiving CAN Messages
To receive data, you can use the readMsgBuf and checkReceive functions:
unsigned char len = 0;
unsigned char buf[8];
if (CAN_MSGAVAIL == CAN.checkReceive()) {
CAN.readMsgBuf(&len, buf); // Read data: len = data length, buf = data byte(s)
unsigned long canId = CAN.getCanId();
Serial.print("Message received with ID: ");
Serial.print(canId, HEX);
Serial.print(" Data: ");
for (int i = 0; i < len; i++) {
Serial.print(buf[i], HEX);
Serial.print(" ");
}
Serial.println();
}
Best Practices
Ensure that the CAN bus network has proper termination resistors.
Avoid long wires in the CAN bus to minimize signal reflection.
Use twisted pair cables for CAN_H and CAN_L to reduce electromagnetic interference.
Troubleshooting and FAQs
Common Issues
CAN Bus Shield not recognized: Ensure that the shield is properly seated on the Arduino and that the SPI pins are not being used by another device.
CAN Bus not communicating: Check the baud rate settings and ensure that all devices on the network are configured with the same rate.
No data being received: Verify that the CAN bus has termination resistors and that the wiring is correct.
Solutions and Tips
Use the CAN.init_Filt() and CAN.init_Mask() functions to configure message filtering if you're only interested in certain CAN IDs.
If you're experiencing noise on the CAN bus, try lowering the baud rate or improving the bus wiring.
Always use the latest version of the MCP_CAN library for compatibility and bug fixes.
FAQs
Q: Can I use multiple CAN Bus Shields on the same network?
A: Yes, you can use multiple shields on the same CAN network, but each device must have a unique ID.
Q: What is the maximum length of the CAN bus?
A: The maximum length depends on the baud rate; for example, at 500 kbps, the maximum length is typically around 100 meters.
Q: How do I know if my CAN Bus Shield is working?
A: You can test the shield by sending messages and checking if they are received by another CAN device. The onboard LED indicators can also provide a visual indication of activity.
For further assistance, consult the SEEED forums or contact technical support.
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