Overview

The can_mcp2515 node interfaces with the MCP2515 CAN bus controller via SPI, paired with a TJA1050 or MCP2551 CAN transceiver. CAN (Controller Area Network) is the standard bus protocol for automotive and industrial systems, providing robust, multi-master, priority-based communication. Use this node to read vehicle OBD-II data, interface with industrial equipment, or build custom CAN networks.

1Mbps

Max Bitrate

Bytes per Frame

2048

Standard IDs

40m

Max Bus Length (1M)

Properties

Property	Type	Required	Default	Description
spiBus	number	No	0	SPI bus number
spiDevice	number	No	0	SPI chip select (CE0=0, CE1=1)
spiSpeed	number	No	10000000	SPI clock speed in Hz (max 10MHz)
intPin	number	No	25	GPIO pin for MCP2515 interrupt output
oscillator	select	No	"8"	Crystal oscillator frequency in MHz: "8", "16", "20"
bitrate	select	No	"500k"	CAN bus bitrate: "5k", "10k", "20k", "50k", "100k", "125k", "250k", "500k", "1000k"
mode	select	No	"normal"	Operating mode: "normal", "loopback" (self-test), "listen" (read-only)

Inputs

Send CAN Frame

{
  "payload": {
    "id": 1824,
    "data": [0x02, 0x01, 0x0C, 0x00,
             0x00, 0x00, 0x00, 0x00],
    "ext": false,
    "rtr": false
  }
}

OBD-II PID Request (Engine RPM)

{
  "payload": {
    "id": 2015,
    "data": [0x02, 0x01, 0x0C, 0x00,
             0x00, 0x00, 0x00, 0x00]
  }
}

Outputs

Received CAN Frame

{
  "payload": {
    "id": 2024,
    "data": [0x04, 0x41, 0x0C, 0x1A,
             0xF8, 0x00, 0x00, 0x00],
    "dlc": 8,
    "ext": false,
    "rtr": false
  },
  "timestamp": "2025-01-15T10:30:00.000Z"
}

TX Confirmation

{
  "payload": true,
  "id": 1824,
  "topic": "can/tx/done"
}

Wiring Diagram

MCP2515 Module to Raspberry Pi

  MCP2515 Module         Raspberry Pi
  +-------------+       +--------------+
  | VCC   (5V)  |-------| 5V    (Pin 2)|
  | GND         |-------| GND   (Pin 6)|
  | CS          |-------| CE0   (Pin 24)|
  | SO  (MISO)  |-------| MISO  (Pin 21)|
  | SI  (MOSI)  |-------| MOSI  (Pin 19)|
  | SCK         |-------| SCLK  (Pin 23)|
  | INT         |-------| GPIO25(Pin 22)|
  +-------------+       +--------------+

         CAN Bus
  +-------------+       +-------------+
  | CAN_H  -----|-------|----- CAN_H  |
  | CAN_L  -----|-------|----- CAN_L  |
  | GND    -----|-------|----- GND    |
  +-------------+       +-------------+
   MCP2515 Module        Target Device

Wiring Notes

VCC use 5V for the MCP2515 module (has onboard regulator)

INT active-low interrupt, triggers on RX or error

CAN_H / CAN_L differential pair, use twisted pair cable

Termination 120 ohm resistor at each end of bus

Warning: Verify your oscillator frequency matches the module hardware. Most cheap modules use 8MHz crystals. Using the wrong setting will result in no communication.

Example Use Cases

OBD-II Vehicle Diagnostics

Query engine RPM and coolant temperature via OBD-II PIDs and display on dashboard gauges.

inject (1s) → can_mcp2515 (tx/rx) → function (decode PID) → gauge

[
  {
    "id": "obd-poll",
    "type": "inject",
    "repeat": "1",
    "payload": "{ "id": 2015, "data": [2, 1, 12, 0, 0, 0, 0, 0] }",
    "payloadType": "json"
  },
  {
    "id": "can-bus",
    "type": "can_mcp2515",
    "spiBus": 0,
    "spiDevice": 0,
    "intPin": 25,
    "oscillator": "8",
    "bitrate": "500k",
    "mode": "normal"
  },
  {
    "id": "decode-pid",
    "type": "function",
    "name": "Decode OBD-II RPM"
  },
  {
    "id": "rpm-gauge",
    "type": "gauge",
    "name": "Engine RPM",
    "min": 0,
    "max": 8000
  }
]

Industrial CAN Sensor Network

Monitor CAN bus traffic from industrial sensors and log all frames to InfluxDB for analysis.

can_mcp2515 (listen) → switch (by CAN ID) → influxdb

[
  {
    "id": "can-listen",
    "type": "can_mcp2515",
    "bitrate": "250k",
    "mode": "listen",
    "oscillator": "8"
  },
  {
    "id": "route-id",
    "type": "switch",
    "property": "payload.id",
    "rules": [
      { "t": "eq", "v": "256" },
      { "t": "eq", "v": "512" },
      { "t": "else" }
    ]
  },
  {
    "id": "store-influx",
    "type": "influxdb",
    "measurement": "can_frames"
  }
]

Loopback Self-Test

Verify MCP2515 wiring and configuration using loopback mode (no external bus needed).

[
  {
    "id": "test-inject",
    "type": "inject",
    "payload": "{ "id": 100, "data": [1, 2, 3, 4] }",
    "payloadType": "json"
  },
  {
    "id": "can-loopback",
    "type": "can_mcp2515",
    "bitrate": "500k",
    "mode": "loopback",
    "oscillator": "8"
  },
  {
    "id": "verify-rx",
    "type": "debug",
    "name": "Loopback RX"
  }
]

Common Use Cases

Vehicle OBD-II

Read engine data, DTCs, and live sensor values from cars

Industrial Automation

Interface with CAN-based PLCs, actuators, and controllers

Bus Sniffing and Logging

Monitor and record all CAN traffic for analysis and debugging

Robotics and Drones

CAN-based motor controllers and sensor fusion networks

Related Nodes

modbus

Modbus RTU/TCP industrial protocol

spi

Raw SPI bus communication

serial

Serial port communication