Developing CAN FD Applications with the Raspberry Pi Zero

This post explores how to implement CAN FD communication using a Raspberry Pi Zero, featuring the PiCAN FD Zero HAT from Copperhill Technologies.

Introduction

The Controller Area Network (CAN) has long been a staple communication protocol in automotive, industrial, and embedded systems due to its robustness, real-time capabilities, and fault-tolerance. With the advent of CAN FD (Flexible Data-rate), developers can now transmit larger data payloads at higher speeds, opening the door to more complex and data-intensive applications. Pairing this advanced protocol with the compact and cost-effective Raspberry Pi Zero enables powerful, lightweight, and economical embedded solutions.

This essay explores the integration and development of CAN FD applications using the Raspberry Pi Zero, with a specific focus on the PiCAN FD Zero HAT from Copperhill Technologies. We will examine the technical specifications and capabilities of the Raspberry Pi Zero, delve into the features of the PiCAN FD Zero HAT, and walk through a high-level guide to CAN FD development on this platform.

Understanding the Raspberry Pi Zero

Overview

The Raspberry Pi Zero is a compact, minimalist version of the larger Raspberry Pi single-board computer (SBC) family. Released in 2015, the Pi Zero was developed to offer essential computing power in an extremely small and affordable package, making it ideal for embedded systems, Internet of Things (IoT) applications, and hardware prototyping.

Technical Specifications

• Processor: 1GHz single-core ARM11 CPU (Broadcom BCM2835)

• RAM: 512MB LPDDR2 SDRAM

• Ports:

  • 1× Mini HDMI port

  • 1× Micro USB OTG port

  • 1× Micro USB power port

  • 1× 40-pin GPIO header (unpopulated)

• Networking: No built-in Ethernet or Wi-Fi (the Pi Zero W and Pi Zero 2 W add wireless capabilities)

• Storage: microSD card slot for OS and data

• Size: 65mm × 30mm × 5mm

• Power Consumption: Extremely low, ideal for battery-powered projects

Despite its small footprint and limited resources compared to more powerful Raspberry Pi models, the Pi Zero remains a compelling platform for lightweight tasks such as sensor management, automation control, and communication interfacing—particularly when paired with external HATs (Hardware Attached on Top).

CAN FD and Its Importance

What Is CAN FD?

CAN FD (Flexible Data-rate) is an enhancement of the classical CAN protocol (ISO 11898-1) developed by Bosch. While it retains backward compatibility with standard CAN, it introduces key improvements:

• Increased Data Payload: Up to 64 bytes per frame (vs. 8 bytes in classical CAN)

• Higher Bit Rates: Data phase speeds up to 5 Mbps or more

• More Efficient Bandwidth Usage: Reduces latency in transmitting larger datasets

• Enhanced Protocol Flexibility: Supports dynamic bit rate switching

These improvements make CAN FD more suitable for modern applications that demand greater bandwidth, such as ADAS (Advanced Driver-Assistance Systems), EV battery management, and high-speed industrial automation.

Introducing the PiCAN FD Zero HAT

One of the most efficient and ready-to-use solutions for bringing CAN FD capabilities to the Raspberry Pi Zero is the PiCAN FD Zero CAN FD HAT, offered by Copperhill Technologies. This add-on board provides a seamless hardware interface for CAN FD networking.

Key Features

• CAN FD Controller: Microchip MCP2518FD

• CAN FD Transceiver: Microchip MCP2562FD

• Interface: SPI (Serial Peripheral Interface) connection to the Raspberry Pi Zero

• Power: 3.3V from Raspberry Pi

• GPIO Pass-Through: Maintains access to GPIO pins via stacking headers

• SocketCAN Compatibility: Fully supported under Linux via SocketCAN, enabling easy use with command-line tools and custom applications

• Optional 120-ohm Termination: Jumper-configurable on the board

• Compact Form Factor: Tailored for the size of the Raspberry Pi Zero

Advantages

• Plug-and-Play Development: No need for manual wiring or custom PCB development

• Linux-Friendly: Works with Raspbian and other Pi-compatible Linux distributions

• Open Source Support: Extensive community examples and integration with CANopen, J1939, and custom CAN stacks

• Durability: High-quality build ideal for prototyping and deployment

Setting Up CAN FD on the Raspberry Pi Zero

Hardware Setup

1. Assemble the Hardware:

   • Solder headers (if not already pre-soldered) onto the Raspberry Pi Zero and PiCAN FD Zero HAT.

   • Stack the HAT onto the Pi Zero GPIO header.

   • Insert a microSD card with Raspberry Pi OS.

   • Connect power to the Pi Zero via micro USB.

2. Connect to a CAN FD Network:

   • Use a DB9-to-DB9 cable or terminal block to connect to other CAN FD devices.

   • Ensure appropriate termination is enabled at each end of the bus.

Software Configuration

1. Update and Install Dependencies:

   sudo apt update sudo apt upgrade sudo apt install can-utils

2. Enable SPI Interface: Use raspi-config or edit /boot/config.txt:

   sudo nano /boot/config.txt

   Add:

   dtparam=spi=on

3. Configure Device Tree Overlay: Add the following line to /boot/config.txt:

   dtoverlay=mcp2518fd,spi0-0,interrupt=25

   This assumes the interrupt is wired to GPIO 25, which is standard for the PiCAN FD Zero.

4. Reboot the Pi:

   sudo reboot

5. Bring Up the CAN Interface:

   sudo ip link set can0 up type can bitrate 500000 dbitrate 2000000 fd on

   You can confirm functionality with:

   ifconfig can0

6. Send and Receive CAN FD Frames:

   • Sending:

     cansend can0 123##0112233445566778899AABBCCDDEEFF

   • Receiving:

     candump can0

Application Scenarios

Using the Raspberry Pi Zero and PiCAN FD Zero, developers can build applications in:

• Automotive Diagnostics & Logging: Lightweight data loggers for CAN FD-enabled vehicles.

• EV Battery Monitoring: Track voltages, temperatures, and BMS data using CAN FD.

• Industrial Equipment Interfaces: Integrate modern machinery into legacy control networks.

• IoT Gateways: Bridge CAN FD data to the internet via MQTT, REST APIs, or cloud services.

• Simulation & Testing: Create test rigs for CAN FD systems, simulating node behavior.

Limitations and Considerations

While the Raspberry Pi Zero offers a powerful platform for low-cost CAN FD development, developers should be aware of a few limitations:

• Single-Core CPU: May struggle with CPU-intensive real-time tasks under high bus load.

• No Built-in Networking: The base Pi Zero lacks Wi-Fi or Ethernet (resolved in Pi Zero W).

• Limited Power Output: Be mindful when powering additional devices from the Pi’s GPIO.

Despite these constraints, the Pi Zero excels in cost-sensitive, compact deployments where size and power consumption are critical.

Conclusion

The Raspberry Pi Zero, paired with the PiCAN FD Zero HAT, offers an affordable and compact solution for developing and deploying CAN FD applications. With full support from the Linux SocketCAN framework, compatibility with open-source tooling, and a vibrant development community, this combination is ideal for anyone looking to explore modern CAN technologies in a flexible and accessible way.

Whether you're a hobbyist prototyping your next robotics project, an automotive engineer logging vehicle data, or an industrial developer integrating factory systems, the Pi Zero + PiCAN FD Zero HAT provides a compelling, scalable, and cost-effective development platform.