CDMA (Code Division Multiple Access) network has the characteristics of wide coverage, high efficiency and low cost. The data transmission rate of CDMA network can reach 200kb / s. The embedded remote video system developed here is to make full use of CDMA network technology and embedded system. The data transmission system built with characteristics is especially suitable for remote or remote places that do not have conventional network transmission conditions, such as car video systems, traffic intersections (real-time monitoring of license plates) and city street lights.
The processor selected for this system is a mid-to-high-end arm9 core CPU-S3C2410 from SAMSUNG, which has a built-in MMU (memory management unit), the main frequency can reach 203MHz, and the embedded Linux2.4 system runs just like a fish, not only maintains It has the characteristics of miniaturization, low power consumption and easy portability of embedded systems, and it fully utilizes the memory, file and thread management functions of Linux system, which greatly facilitates the development of programs and the realization of multi-task functions in programs
1 Embedded Linux system
Linux itself as a desktop system, its biggest feature is that the source code of the operating system is open and follows the GPL protocol. Its kernel adopts a modular design, which is easy to cut down. It is especially suitable for the miniaturization requirements of embedded systems and occupies the embedded system. Half of the country.
2 System structure
The system can generally be divided into real-time and trigger modes. You can design a suitable method according to the specific situation. If you use real-time, it will occupy more network resources and the cost is relatively high. The operating cost of using the trigger mode is lower. Mode, system structure is shown in Figure 1.
When an abnormal situation is encountered, the terminal is triggered to take a picture, and its internal embedded module and CDMA module work together to complete Internet access (including dial-up, PPP and CTP / IP protocol processing, etc.), and the captured picture The data is packaged and sent to the central host, or sent to the specified E-mail address. After the central host logs on the Internet and runs the server-side software, you can browse the pictures sent by the point.
3 hardware system design
To be able to run an operating system correctly, the hardware should include at least the CPU, memory and solid-state storage, system internal and peripheral interfaces.
SAMSUNG's S3C2410 CPU has 3 UART, 1 RTC and touch screen interface, and also has I2C, USB Host, USB Device and other interfaces, which fully meet the needs of the system, and the cost performance is extremely high, it is a very good choice.
Since the cropped Linux system occupies very little storage space (only a few MB), we chose Nor Flash as the solid-state memory, the model is E28F128J3A150, the capacity is 16MB, exchange data with the CPU through 16-bit data, and use its upper 8MB space (00800000H-00ffffffH) developed a jffs2 file storage system to store the configuration files of the system.
The 64MB SDRAM is 2 pieces of K4S561632C, and exchanges data with the CPU through 32-bit data.
The MAX3232C level conversion chip and the RTL8019 network chip are converted into an RS-232 interface and an Ethernet interface, which are connected to the PC with a serial cable and an Ethernet network cable to form a development environment that can be cross-compiled.
Connect directly to the USB camera through the USB Host interface integrated on the CPU. Considering the requirements of the monitoring and control module interface, the infrared camera with USB 1.1 interface is selected.
It is directly connected to the CDMA Modem module through the integrated UART interface on the CPU, and selects the affordable DTGS-800 CDMA module of AnyData.
High purity Tin wire is a special target material, Vacuum coating target technology was used in Automobile glass.
Pure Tin Wire,Tin Wire,Tin Solder Wire,Tin Plated Copper Wire
Shaoxing Tianlong Tin Materials Co.,Ltd. , https://www.tianlongspray.com