20 Controller Area Network Interview Questions and Answers

Controller Area Network (CAN) is a vehicle bus standard designed to allow microcontrollers and devices to communicate with each other in applications without a host computer. It is a message-based protocol, designed originally for multiplex electrical wiring within automobiles, but is also used in many other contexts. When interviewing for a position that will require you to work with CAN, it is important to be prepared to answer questions about the protocol. This article discusses some of the most common questions you may be asked about CAN during your interview.

Controller Area Network Interview Questions and Answers

Here are 20 commonly asked Controller Area Network interview questions and answers to prepare you for your interview:

1. What is Controller Area Network (CAN)?

Controller Area Network (CAN) is a vehicle bus standard designed to allow microcontrollers and devices to communicate with each other within a vehicle without a host computer.

2. How does a CAN bus work?

A CAN bus is a high-speed data network used in vehicles. It allows different electronic control units (ECUs) to communicate with each other. The CAN bus uses a two-wire bus to connect all the ECUs in a vehicle. The bus uses a twisted pair of wires to reduce electromagnetic interference.

3. Can you explain what arbitration is in the context of CAN?

Arbitration is the process that the CAN controller uses to determine which node on the network gets to transmit data at any given time. When two nodes try to transmit data at the same time, the CAN controller uses a process of arbitration to decide which node gets to go first.

4. What are some advantages of using CAN bus protocol?

Some advantages of using CAN bus protocol include its high immunity to electrical noise, its high data transmission rate, and its support for multiplexing. Additionally, because CAN bus is a broadcast protocol, all nodes on the network can receive messages, which can be helpful in certain situations.

5. What’s the difference between CAN FD and CAN 2.0B?

CAN FD is an extension of the CAN 2.0B specification that was developed in order to improve CAN’s data transmission capabilities. CAN FD allows for a higher data bit rate and supports larger data frames.

6. Which types of vehicles support CAN bus protocols?

CAN bus protocols are most commonly found in vehicles such as cars and trucks. However, they are also used in other types of vehicles such as buses, trains, and boats.

7. What is the maximum speed supported by legacy CAN?

The maximum speed supported by legacy CAN is 1Mbps.

8. What do you understand about ISO 15765-4, ISO 11898-1, and SAE J1939 standards?

The ISO 15765-4 standard defines the Controller Area Network (CAN) for road vehicles, while the ISO 11898-1 standard defines the CAN for industrial applications. The SAE J1939 standard is a set of standards developed by the Society of Automotive Engineers (SAE) for use in the automotive industry.

9. Is it possible to implement error detection on CAN network? If yes, then how?

Yes, it is possible to implement error detection on a CAN network. There are a few different ways to do this, but one common method is to use a checksum. This checksum is calculated by the sender and included with the data that is sent. The receiver can then recalculate the checksum and compare it to the one that was sent. If they match, then the data is assumed to be correct.

10. What are the main components that comprise a standard CAN system?

The main components of a standard CAN system are the controller, the transceiver, and the bus. The controller is responsible for generating the CAN signals and for managing the data that is transmitted on the bus. The transceiver is responsible for converting the CAN signals into electrical signals that can be transmitted on the bus. The bus is responsible for connecting the controller and the transceiver and for carrying the CAN signals between them.

11. What are the different frame formats used in CAN?

There are three different frame formats used in CAN: Standard, Extended, and Remote. Standard frames are the most common, and are used for most data transmissions. Extended frames are used for data that is longer than 8 bytes, and Remote frames are used to request data from another node.

12. What are the differences between CAN High Speed and CAN Low Speed?

CAN High Speed is a faster version of the Controller Area Network protocol that is typically used in automotive applications. CAN Low Speed is the original version of the protocol and is used in a variety of industrial and commercial applications.

13. What are the differences between Private and Public CAN networks?

The main difference between private and public CAN networks is that private networks are used for closed systems where all of the nodes are known and trusted, while public networks are used for open systems where any node can join or leave the network at any time. Private networks are typically used in industrial or automotive applications, while public networks are used in public transportation or other applications where it is important to be able to add or remove nodes from the network without disrupting the entire system.

14. Can you give me an example of when you might use a Private CAN over a Public CAN?

A Private CAN is typically used in cases where security is a concern, such as in military or industrial applications. A Public CAN is typically used in less sensitive applications where cost is a greater concern.

15. Can you name some devices that can be connected to a CAN bus?

Some devices that can be connected to a CAN bus include:

-Computers
-Sensors
-Actuators
-Displays
-Cameras
-Printers

16. Why must CAN messages always have at least one data byte?

CAN messages always have at least one data byte because the message ID is only 11 bits, which is not enough to uniquely identify a message. The data byte allows for the message to be uniquely identified.

17. What are the three main areas where CAN is extensively used?

The three main areas where Controller Area Network is extensively used are in automotive applications, industrial automation, and medical equipment.

18. What types of cars use CAN bus protocol?

Any car that has electronic control units for its engine, transmission, anti-lock brakes, and airbags will likely use CAN bus. Many modern cars use CAN bus protocol.

19. What is the importance of ID length in CAN frames?

The ID length is important in CAN frames because it determines how many bits are used to identify the source and destination of the message. The longer the ID, the more information can be conveyed.

20. What happens if there is a collision on the CAN bus?

If there is a collision on the CAN bus, then the bus will be locked until the collision is resolved. This is because the CAN bus uses a CSMA/CD protocol, which means that collisions are detected and then resolved before any data is transmitted.