In the face of increasingly fierce market competition and increasingly discerning users, automakers and auto parts suppliers have been working hard to innovate – products with newer technology and better user experience are constantly being applied to cars. Advanced in-vehicle infotainment systems have entered a new era of technology. It has evolved from a simple system that originally controlled radios or air conditioners to a complex large system that now includes hands-free phones, satellite navigation, Internet services, and front- and rear-seat audio and video playback that supports multiple media. Whether it is high-end products or low-end products, the hardware and software design of this system must meet strict security standards, but also have good ease of use and flexibility. This article will give some thoughts on the software design of the system from the aspects of security, real-time, environmental protection and novelty, hoping to help engineers who are engaged in the development of such systems.
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safety
The security mentioned here refers to (1) the system can provide effective services for a long time without failure; (2) the system can handle the fault itself if there is a fault; (3) the system can automatically save the fault diagnosis file.
The principles of dealing with security-related issues are isolation and redundancy. Isolation is modular. Redundancy is to increase backups. For hardware design, modularity and the addition of redundant devices are straightforward. The actual challenge comes from the security design of the software, and most system failures are due to software errors. Well-designed software modules should ensure that failures in one module do not cause other modules to fail, and do not cause the entire system to fail; the actual system design should also ensure that the failed module is quickly restarted or backed up in time. Module replacement, while the rest of the system is functioning properly.
For example, if a task in the system fails - you want to overwrite the memory area belonging to another task, the system monitor monitors that this is an illegal event, restarts the failed task, and saves the troubleshooting file. For developers to solve problems in the future - the monitoring program can record the system status when the fault occurs in great detail, which can help developers quickly locate the problem.
Obviously, for a large system such as an in-vehicle infotainment system, the traditional single-core operating system is difficult to implement the above-exemplified operations because the memory space of the kernel task and the application is not sufficiently isolated. The QNX micro-kernel real-time operating system, which is very popular in the industry, has fully realized the isolation of various system services after years of practice and innovation, and has become a good foundation for designing high-security software.
real-time
Simply put, real-time is the result of a system task getting effective in a valid time.
The in-vehicle infotainment system is a multi-tasking complex system that contains many subsystems that interact with the car network, such as CAN and MOST, as well as other communication protocols such as RS232, Ethernet, and Bluetooth. It is important to consider the real-time characteristics of the system from the beginning of system software design. On the one hand, the introduction of real-time design can bring users a better application experience, such as stable and smooth multimedia playback, accurate and effective navigation prompts; on the other hand, the system's real-time design can guarantee certain mission-critical tasks. Smooth execution, such as Bluetooth phone and reversing screen playback. Conversely, if the system does not handle the priority and real-time of each task well, then in the actual operation of the system, one or more tasks will inevitably fail to complete in time, resulting in system failures and user complaints. .
More critically, the entire system is so complex that it typically takes hundreds of milliseconds from a shutdown state (power is completely turned off) to a system boot into normal operation. When the car starts up, the CAN device typically sends a power-on signal within 65 milliseconds. The infotainment system connected to the CAN bus must be ready to receive the power-on signal in 55 milliseconds or less and respond to the power-on signal within 100 milliseconds. If the infotainment system is unable to respond to the CAN power-on signal in time, it will most likely be considered a faulty CAN device and will be excluded from the CAN network.
Starting from a real-time design, the system must start the information of the corresponding CAN network before completing the initialization. The traditional approach is to use additional auxiliary devices to perform such tasks - increasing hardware costs. These auxiliary devices can now be completely eliminated with QNX's "mini-driver" technology. The mini-driver is designed to allow certain device drivers, such as CAN drivers, to be used during system startup - to successfully handle event responses from the CAN network; when the system is booted, a more complete driver will take over all of the mini-drivers. Mission - Software costs are low.
Environmental protection
Environmental protection means that the system can effectively manage power.
Power management in the car is a very challenging task. The car's power source is a battery with limited power. After the car is turned off, on the one hand, the in-vehicle system, especially the infotainment system, cannot have excessive power consumption, and it must be ensured that the normal battery can still be ignited smoothly after several days or even weeks; on the other hand, the infotainment system It is also necessary to be able to respond effectively and timely to specific events in an ultra-low energy state. Without a multi-level standby state, the system must be fully restarted each time, not only does it have a long boot time each time, but it is also difficult to meet the correct response to many real-time events, such as the CAN described in the previous section. Power on signal.
The solution is to customize the multi-level standby state according to specific needs, so that the infotainment system can gradually enter the low-power standby state over time and the battery power drops until it is completely shut down. In each different standby state, the system can respond to specific events and enter a working state in a short enough time.
However, the traditional power management standards APM (Advanced Power Management) and ACPI (Advanced Configuration and Power InteRFace) are difficult to apply to the power management program of the in-vehicle infotainment system. APM and ACPI are mainly used for power management of personal computers. APM is a program that runs on the BIOS (a device that is rarely used on in-vehicle infotainment systems). The computer's application or operating system basically does not know the power management decisions made by APM, so this solution cannot provide what we need. Customizable multi-level power management status. ACPI uses a method that determines the state of power management by the operating system, which can make more complex and efficient power management. However, in the in-vehicle infotainment system, the operating system often does not know the specific power status of each application, such as whether the car is turned off, whether the Bluetooth device is working, etc., and these are the key points of the vehicle system power management, so ACPI can not be satisfied. Vehicle system power management requirements.
Based on the QNX operating system, power management can be developed as an application. In this way, system designers can design targeted power management solutions based on different system requirements. Through the communication between applications and between the application and the operating system, the power status of each system module can be precisely controlled, so that energy can be used effectively and environmental protection can be promoted.
Novelty
Novelty means that the product has a personality and should be distinguished from other similar products.
For in-vehicle infotainment systems, novelty means a human-machine interface that can be quickly customized to customer requirements and a graphical, rich-looking graphic display, whether it be a media player, a web browser, or a satellite navigation system. All of this is related to the development of graphical user interfaces. How to modularize the human-machine interface well in the design stage is a key issue that designers must consider when designing. Otherwise, it will be very painful to face the new demands of customers in the future - whether to redesign the software or reject the customer's needs. ? Not only that, if the human-machine interface is not well modularized, and sometimes the underlying protocol changes, redesigning the human-machine interface is an inevitable problem.
Therefore, the modularity of the human-machine interface is not only the stripping of the shell, it actually contains the definition of data expression and the definition of device operation. Since the human-machine interface portion is usually a large part of the code for the in-vehicle infotainment system, high-quality modular human-machine interface programs and related drivers can significantly reduce the cost of system expansion. On the one hand, modularity increases the reusability of code, and on the other hand, they also reduce the investment in testing. I hope that design developers can fully consider this issue.
Summary of this article
This paper puts forward some thoughts on the software design of in-vehicle infotainment system from four aspects: security, real-time, environmental protection and novelty. I hope these ideas can bring some impetus to the booming Chinese automotive electronics.
To say it, today's technology is the same day by day. In the past few years, optical fiber was still an advanced term, and the price of optical fiber equipment was also scary. Nowadays, optical fiber has begun to spread widely, and the price of optical fiber equipment has dropped with the development of technology. At the same time, with the development of technology, there are more and more vocabulary, such as the PoE-ONU we are going to talk about today.
Advantages of PoE-ONU
Over the years, with the development of projects such as "light-in-copper-retreat" and "fiber-to-the-home", the popularity of ONUs has also become higher and higher. Friends who have worked on PON networks basically know ONU, which is an access terminal device used in PON network, which is equivalent to the access switch in our usual network.
The PON network is a passive optical network. The reason why it is said to be passive is that the optical fiber transmission between the ONU and the OLT does not require any power equipment. The PON uses a single optical fiber to connect to the OLT, and then the OLT connects to the ONU. The use of PON technology for networking can save half of the optical fiber, and the transmission distance is longer.
Although some expenses have been saved, can we save a little more? of course can! With the development of technology, more and more devices are connected to ONU. Many of these devices require power supply. As a result, the wiring is complicated and the operation and maintenance of the devices also require a lot of manpower. In some special environments, the inconvenience of power supply is even worse.
Reverse Poe Onu,Poe Power
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