How to Use Adafruit Feather M4 Express CAN: Examples, Pinouts, and Specs

The Adafruit Feather M4 Express CAN is a versatile and powerful development board that harnesses the capabilities of the ATSAMD51 microcontroller. This board is part of the Feather ecosystem, known for its compact size, portability, and extensive I/O options. The inclusion of CAN-Bus connectivity makes it ideal for automotive applications, industrial automation, and any project where robust serial communication is required. The ARM Cortex-M4 core with a floating-point unit runs at 120 MHz, providing high computational performance for complex tasks.

• Automotive diagnostics and networking
• Industrial control systems
• Home automation
• Robotics
• Data logging and telemetry

• Microcontroller: ATSAMD51J19
• Clock Speed: 120 MHz
• Flash Memory: 512 KB
• SRAM: 192 KB
• Operating Voltage: 3.3V
• I/O Pins: 21, with 12 PWM and 6 ADC channels
• CAN Controller: MCP2515 with SN65HVD230 transceiver

1. Powering the Board: Connect a 3.7V LiPo battery to the JST connector for portable applications or supply 5V to the USB or VBUS pin for stationary projects.
2. Programming: Use the USB interface to program the board with the Arduino IDE or CircuitPython.
3. Connecting to CAN-Bus: Attach the CAN_H and CAN_L lines from your CAN network to the CAN_RX and CAN_TX pins, respectively.

• Ensure that the power supply is within the recommended voltage range to prevent damage.
• When using the CAN-Bus, a 120-ohm termination resistor may be necessary at both ends of the bus for proper communication.
• Use proper ESD precautions when handling the board to avoid static damage to the microcontroller.

• Board not recognized by computer: Check the USB cable and connections; try a different USB port or cable.
• CAN-Bus communication errors: Verify the termination resistors and the integrity of the CAN_H and CAN_L connections.
• Sketch upload failure: Ensure the correct board and port are selected in the Arduino IDE.

• If the board is not recognized, press the reset button twice quickly to enter bootloader mode.
• For CAN-Bus issues, use a CAN-Bus analyzer to monitor the network and diagnose communication problems.
• Check for updates to board definitions or drivers if you encounter upload issues.

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

// Initialize MCP_CAN instance with SPI CS Pin 10
MCP_CAN CAN0(10);

void setup() {
  Serial.begin(115200);

  // Initialize CAN0 at 500 kbps
  if (CAN0.begin(MCP_ANY, CAN_500KBPS, MCP_8MHZ) == CAN_OK) {
    Serial.println("CAN Bus Module Initialized Successfully!");
  } else {
    Serial.println("CAN Bus Module Initialization Failed!");
  }
}

void loop() {
  // Check if data is available to read
  if (CAN0.checkReceive() == CAN_MSGAVAIL) {
    unsigned char len = 0;
    unsigned char buf[8];

    // Read data: len = data length, buf = data byte(s)
    CAN0.readMsgBuf(&len, buf);

    // Print received data
    for (int i = 0; i < len; i++) {
      Serial.print(buf[i], HEX);
      Serial.print(" ");
    }
    Serial.println();
  }
}

Note: This example demonstrates basic CAN-Bus communication using the MCP_CAN library. Ensure that the library is installed in your Arduino IDE before compiling the sketch. Adjust the CS pin number and CAN bus speed according to your specific setup.