CAN Bus Explained - A Simple Intro [v2.0 | 2021] 🌟

Summary

This video tutorial explains the basics of Controller Area Network (CAN) bus technology, commonly used in vehicles and machinery. It covers how CAN bus enables communication between different electronic control units (ECUs), like the engine or airbags, through a simple, low-cost system. The video explores the key benefits of CAN bus, such as simplicity, centralization, robustness, and efficiency. It also delves into CAN bus history, standards, and the structure of CAN frames, providing a detailed breakdown. Additionally, the video discusses how to record and decode CAN bus data for practical applications like fleet management, predictive maintenance, and diagnostics.

Takeaways

• 😀 CAN bus is like a nervous system for vehicles, allowing different parts (ECUs) to communicate seamlessly.
• 😀 Modern cars may have up to 70 ECUs, such as engine control units, airbags, and audio systems, all interconnected via the CAN bus.
• 😀 The CAN bus system eliminates the need for complex wiring, allowing ECUs to broadcast data to each other through two wires: CAN low and CAN high.
• 😀 CAN bus is low-cost, simple, and reduces errors, weight, wiring, and costs by using a single communication system.
• 😀 The system is centralized, enabling easy diagnostics, data logging, and configuration across all ECUs in the network.
• 😀 CAN bus is highly robust, making it ideal for safety-critical applications by being resistant to electromagnetic interference.
• 😀 CAN bus is efficient, using CAN IDs to prioritize high-priority data without interrupting other communications.
• 😀 The CAN bus standard was developed by Bosch in 1986 and has evolved into the CAN 2.0, CAN FD, and CAN XL protocols.
• 😀 Communication over CAN bus is done through CAN frames, which contain 8 message fields, including the CAN ID and data payload.
• 😀 To decode raw CAN bus data, you need a DBC file and a CAN bus data logger, with common use cases including fleet management, predictive maintenance, and vehicle diagnostics.

Q & A

What is CAN bus, and what role does it play in a vehicle?

CAN bus (Controller Area Network) is a communication system that enables electronic control units (ECUs) in a vehicle to exchange data efficiently. It acts like the nervous system of the car, allowing different parts of the vehicle, such as the engine control unit, airbags, and audio system, to communicate with each other through a shared network.

How does the CAN bus system differ from traditional wiring in vehicles?

Traditional vehicles use complex point-to-point wiring for each system to communicate, leading to heavy wiring and higher costs. CAN bus simplifies this by using a single communication network for all ECUs, reducing the complexity and weight of wiring while improving reliability and cost-effectiveness.

What are the key benefits of using CAN bus in vehicles?

The key benefits of CAN bus include its simplicity and low cost, centralized communication system, robustness against electric disturbances and electromagnetic interference, and efficiency in prioritizing data frames to ensure critical information is transmitted promptly.

What are the two primary layers that define the CAN bus protocol?

The two primary layers of the CAN bus protocol are the data link layer, defined by ISO 11898-1, and the physical layer, described by ISO 11898-2. These layers define how data is transmitted and received across the CAN network.

What is the difference between CAN 2.0 and CAN FD?

CAN 2.0 is the original version of the protocol with 11-bit or 29-bit CAN IDs. CAN FD (Flexible Data-rate) is the next generation, which allows for larger data payloads (up to 64 bytes) and faster data transmission speeds, making it suitable for more data-intensive applications like electric vehicles.

What is a CAN frame, and what are its key components?

A CAN frame is the unit of communication in the CAN bus system. It includes several key components: Start of Frame, CAN ID, Remote Transmission Request, Control field, Data payload, Cyclic Redundancy Check (CRC), Acknowledgement, and End of Frame.

Why is the CAN ID important in CAN bus communication?

The CAN ID serves as a unique identifier for each frame and determines the priority of the data. Lower value IDs have higher priority, ensuring that critical data is transmitted first, without being delayed by less important frames.

What is the purpose of CAN bus data logging, and how is it done?

CAN bus data logging captures and stores raw CAN frames for analysis. This is typically done using a CAN logger, which records timestamped data onto a storage medium like an SD card. Specialized adapters and cables are often used to connect the logger to the vehicle or machinery.

How are raw CAN bus data and signals decoded into human-readable values?

Raw CAN bus data contains CAN signals, which represent various parameters like speed or engine temperature. Decoding these signals involves converting the raw data from hexadecimal to decimal and applying linear conversion formulas, based on predefined rules found in DBC files or similar databases.

What challenges arise when decoding proprietary CAN bus data?

The main challenge is that many manufacturers use proprietary encoding schemes for CAN bus data, which are not publicly available. Without access to the relevant DBC file or decoding rules, it can be difficult to interpret the raw data. In some cases, reverse engineering tools or publicly available DBC files may help decode proprietary data.