This is the official repository for the Tinymovr Arduino Nano CAN Bus Shield.
The included example sketch provides a diagnostic loopback test for the shield. This helps verify that your CAN hardware is functioning correctly before connecting to a real CAN network.
- Hardware initialization and power management for MCP25625-based shields
- Loopback mode for self-testing without external CAN devices
- Detailed serial output for debugging
- Sends and receives test messages to verify full CAN stack operation
- Arduino Nano or compatible board (any Nano form factor)
- Classic Arduino Nano (ATmega328P)
- Arduino Nano Every
- Arduino Nano 33 IoT
- Arduino Nano 33 BLE
- Arduino Nano RP2040 Connect
- Arduino Nano ESP32
- Compatible clones
- Tinymovr Arduino Nano CAN Bus Shield
- MCP25625 CAN controller with integrated transceiver
- 16MHz crystal oscillator
- AP3602 5V boost regulator
- Standard SPI connection
A STEP file (nano-shield.step) is included in this repository for mechanical design and enclosure integration.
| Pin | Function | Description |
|---|---|---|
| 10 | CS | SPI Chip Select |
| 2 | INT | Interrupt pin |
| 5 | RST | Hardware reset (active low) |
| 9 | STBY | Standby control (LOW = normal operation) |
| 8 | 5V_SHDN | 5V boost regulator shutdown (HIGH = enabled) |
This sketch requires the autowp-mcp2515 library:
# Install via Arduino Library Manager
# Search for: "autowp-mcp2515"Or install manually from: https://github.com/autowp/arduino-mcp2515
The CAN bitrate can be configured at the top of the sketch (CANBusLoopback.ino:15):
const CAN_SPEED CAN_BITRATE = CAN_500KBPS; // Change this to match your CAN networkSupported bitrates:
CAN_5KBPS- 5 kbpsCAN_10KBPS- 10 kbpsCAN_20KBPS- 20 kbpsCAN_31K25BPS- 31.25 kbpsCAN_33KBPS- 33 kbpsCAN_40KBPS- 40 kbpsCAN_50KBPS- 50 kbpsCAN_80KBPS- 80 kbpsCAN_100KBPS- 100 kbpsCAN_125KBPS- 125 kbps (common in automotive)CAN_200KBPS- 200 kbpsCAN_250KBPS- 250 kbps (common in industrial)CAN_500KBPS- 500 kbps (default, common in automotive)CAN_1000KBPS- 1000 kbps (1 Mbps)
Important: The bitrate must match all other devices on your CAN network. Using different bitrates will prevent communication.
- Upload the sketch to your Arduino
- Open Serial Monitor at 115200 baud
- Observe the initialization sequence and test messages
- You should see messages being sent and received successfully
Expected output:
Starting CAN Shield Test...
[1/4] Configuring pins...
[2/4] Resetting MCP25625...
[3/4] Initializing CAN controller...
[4/4] Setting CAN mode...
Setup Complete! Starting test loop...
Loop #1
-> Sending message (ID: 0x123)... OK
<- Checking for messages... Received!
ID: 0x123 | Data (4 bytes): DE AD BE EF
- Configure the bitrate to match your CAN network (see Configuration section above)
- Connect your CAN shield to a CAN bus (CANH and CANL)
- Ensure proper termination resistors (120Ω) on the bus
- In the code, comment out the loopback mode line and uncomment normal mode:
// mcp.setLoopbackMode(); // Comment this out mcp.setNormalMode(); // Uncomment this line
- Upload and monitor for real CAN traffic
- Check SPI wiring (MOSI, MISO, SCK, CS)
- Verify CS pin is set correctly (default: pin 10)
- Ensure MCP2515/MCP25625 is properly powered
- Confirm 16MHz crystal oscillator is present
- Check that loopback mode is enabled
- Verify the MCP2515 initialized successfully
- Try increasing the delay between send and receive
- Verify bitrate matches - All devices must use the same bitrate
- Check CANH and CANL connections
- Ensure proper bus termination (120Ω resistors at both ends)
- Confirm you've switched to normal mode (not loopback)
- Check that other devices are actively transmitting
- Verify 5V boost regulator is enabled (PIN_5V_SHDN = HIGH)
- Check that standby mode is disabled (PIN_CAN_STBY = LOW)
- Try the hardware reset sequence again
This project is licensed under the Apache License 2.0 - see the LICENSE file for details.
Contributions are welcome! Please feel free to submit issues or pull requests.