MCP2515-CANBUS

# CAN Bus Reader for Vehicles **Script to read CAN bus data from your car using an `Arduino Uno R3` and `MCP2515 CAN Transceiver (with TJA1050 module)`** --- ## Where’s the Code? You’ll find the script in the `src` folder under `main.cpp`. You can also use the same script with `ESP32` or `ESP8266` instead of the Arduino Uno R3. --- ## Wiring Diagram > ⚠️ **NOTE:** CS and INT pins are defined in code. Be careful when changing these, as the INT pin from the MCP2515 outputs **5V**. | MCP2515 | Arduino R3 | OBD2 Connector | |-------------|------------|------------------------| | VCC | 5V | | | GND | GND | | | CS | 10 | | | SO (MISO) | 12 | | | SI (MOSI) | 11 | | | SCK | 13 | | | INT | 2 | | | CAN HIGH | | PIN 6 (CAN H) | | CAN LOW | | PIN 14 (CAN L) | --- ## Configuration Tips - Ensure your Serial Monitor baud rate is set to **250000**. - In the script, check **line 98** and modify it to match your MCP2515 crystal speed (8 MHz or 16 MHz). - On the same line, adjust the **CAN bus speed**: - **1000 Kbps**: Modern ECUs - **500 Kbps**: Standard ECUs - **125 Kbps**: BCM (Body Control Module) --- ## Available Serial Commands | Command | Description | |------------|-----------------------------------------------------------------------------| | `NORMAL` | Sets MCP2515 to Normal mode (default is LOOPBACK on boot) | | `LOOPBACK` | Sets MCP2515 to Loopback mode (test mode for internal frame echo) | | `SEND` | Sends a diagnostic request to the ECU | | `SEND2` | Alternate diagnostic request to the ECU | | `SEND3` | Sends an RPM request to the ECU; expects HEX response with engine RPM | --- ## MCP2515 Mode Descriptions - **NORMAL MODE**: Actively listens for incoming CAN frames, including frames it sends. - **LOOPBACK MODE**: Test mode — MCP2515 does not receive external frames but will "hear" its own messages. --- ## ⚠️ Important Notes & Troubleshooting - This script allows **read/write via Serial** using defined commands. - Some vehicles have a **gateway in the OBD2 port** that blocks direct CAN communication. In that case: - You may need to find another CAN bus port inside the vehicle. - Some vehicles require a **diagnostic request** to start transmitting CAN frames. - If the OBD2 port appears idle, the vehicle may use a different protocol (like ISO/KWP2000) instead of CAN. - In this case, this setup won’t work for CAN, but you can still potentially communicate over **K-Line** using just an Arduino/ESP board and some resistors. ---