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Hardware setup

Compatible boards

Any Arduino with SPI support works. The CS pin and SPI pins vary by board:

Board SCK MOSI MISO CS (recommended) Notes
Arduino Mega 2560 52 51 50 53 Hardware SPI, most headroom
Arduino Uno 13 11 12 10 5V, limited RAM
Arduino Nano 13 11 12 10 Same as Uno, compact
Arduino Micro 15 16 14 10 5V, USB HID capable
Arduino Leonardo 15 16 14 10 Same as Micro
ESP32 18 23 19 5 3.3V — use level shifter

For ESP32, the MCP2515 runs at 3.3V — do not connect directly to a 5V MCP2515 module without a level shifter.

Required components

Component Recommended model
Microcontroller Any board from the table above
CAN module MCP2515 + TJA1050 breakout board
Bus terminators 2× 120 Ω resistor
Wiring Twisted pair for CAN_H / CAN_L

Wiring — Arduino Mega

Arduino Mega MCP2515 module
5V VCC
GND GND
pin 52 SCK
pin 51 MOSI
pin 50 MISO
pin 53 CS
pin 2 INT (optional)

Wiring — Arduino Uno / Nano

Arduino Uno/Nano MCP2515 module
5V VCC
GND GND
pin 13 SCK
pin 11 MOSI
pin 12 MISO
pin 10 CS
pin 2 INT (optional)

Initialization code

Change SPI_CS_PIN to match your board:

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

const int SPI_CS_PIN = 10;  // 53 for Mega, 10 for Uno/Nano
MCP_CAN CAN(SPI_CS_PIN);

void setup() {
    while (CAN_OK != CAN.begin(MCP_ANY, CAN_250KBPS, MCP_8MHZ)) {
        delay(100);
    }
    CAN.setMode(MCP_NORMAL);
}

MCP2515 oscillator

Most MCP2515 modules come with an 8 MHz crystal. Some come with 16 MHz — check the crystal printed on your module and change the parameter accordingly:

Crystal Parameter
8 MHz MCP_8MHZ
16 MHz MCP_16MHZ

Installing the library

Install mcp_can by Cory Fowler from the Arduino IDE library manager, or clone directly:

bash
cd ~/Documents/Arduino/libraries
git clone https://github.com/coryjfowler/MCP_CAN_lib

Important

Always place a 120 Ω resistor between CAN_H and CAN_L at each end of the bus. Without terminators, signal reflections will make the bus unstable.

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