Ethernet was originally developed by Xerox and developed by Xerox, Intel and DEC. The baseband LAN specification is the most common communication protocol standard used in existing LANs, using carrier sense multiple access and collision detection technology. The 10M/S rate runs on many types of cables, and Ethernet is similar to the IEEE802.3 family of standards. In addition to being widely used in industrial control automation networks, Ethernet applications continue to expand to more plant devices and sensor layers. For industrial camera and sensor applications, the reasons for considering the use of Ethernet-based connections and abandoning traditional methods such as analog or LVDS may not be obvious. As shown in Figure 1, the processing cost of the camera and central unit is high. However, many key elements ultimately provide automakers with lower cost and higher performance.
Figure 1. Camera cost
The use of low-cost unshielded cables can significantly reduce cable costs. In addition, standard-based 100BASE-TX Ethernet eliminates the need for additional power cables from Active Ethernet (PoE). However, to understand the true value of Ethernet, you must see a deeper level through a simple bill of materials. A single public network connecting the office, program, control, and device layers remotely identifies, monitors, and controls every device on the network. This not only greatly improves management efficiency, reduces operating costs, but also significantly reduces or even eliminates the risk of more obvious machine failures.
Camera challenge
For designers, any sensor or camera application faces some common key challenges; the development of small-size cameras and sensors for industrial and automotive applications has created more and more space constraints; low power consumption, The thermal noise generated by the camera sensor directly affects the image quality. In the absence of the required space constraints, improved thermal power consumption and lower power are critical to achieving desired performance, low noise consumption, and like thermal noise, electrical noise can also degrade the quality of the sensor image. In addition, industrial EMC emissions must be achieved without the use of high-cost cables (eg, fiber optic cables or shielded cables); high reliability to provide the necessary performance in extreme environments.
In order to prove that the standard Ethernet can meet the requirements of the camera system, Merrill has found the automotive sensor specialist Silicon Micro Sensors GmbH (First Sensor AG) to design a small size for the most demanding applications. Automotive and industrial grade solutions that can be put into production; 1. megapixel (720p) high dynamic range (HDR) camera; 2. field of view between 55° and 190°; 3.MJPEG video compression; 4. ether Network AVB compatible bit stream (MJPEG or UDP); 5. Supports active Ethernet; 6. Speeds over 100Mbps on low-cost unshielded twisted pair; 7. IP68 / IP6k9 standard, waterproof, scratch-resistant, anti- Fog; the basic functional block diagram of the Miri/SMS solution shown in Figure 2 below is very common in all standard Ethernet camera designs.
Figure 2. Ethernet camera function block diagram
The solution offers two options, the Omnivision OV10635 or the ApTIna AR0132AT image sensor. Freescale's MPC5604 processor performs MJPEG compression based on input YUV digital image data and connects to the Mickey KSZ8061 Quiet-WIRE via MII (Media Independent Interface)? 100BASE-TX Ethernet PHY. The Micley DS1001 MEMs oscillator provides system timing. The power supply is managed by an optimized active Ethernet network. The Ethernet physical layer provides a range of advantages to meet the needs of camera systems.
Minimum bill of materials and small size
One of the great advantages of using a standard automotive Ethernet solution is that it provides a minimum standard material list that is independent of the application, as shown in Figure 3 below. This provides economies of scale that exceeds any automotive-specific solution and can result in a multi-vendor model that offers a wider choice and lower cost.
Figure 3. Standard Ethernet bill of materials
The physical layer consists of the Miri KSZ8061 Quiet-WIRE with a size of only 5mm x 5mm? Available with 100BASE-TX Ethernet transceiver. A minimum of power supply filtering must be ensured, and the line interface between the PHY transceiver and the magnetic components does not require additional passive components, which increases signal integrity while reducing cost and space on the PCB. Standard Ethernet magnetic components can also be used. In recent years, Ethernet magnetic components have become popular. Here, we have adopted TDK's latest automotive and industrial Ethernet magnetic components. The ALT4352 series supports surface mount technology; the winding and smaller solution with a winding machine, with a maximum height of only 2.9mm, is ideal for camera modules with limited space. The winding of the magnetic components of the winding machine not only reduces costs, but also has higher accuracy (relative to conventional hand-wound coil sets) and provides more powerful and consistent performance.
Guangzhou Ehang Electronic Co., Ltd. , https://www.ehangmobile.com