Abstract: This article proposed one kind of network video frequency supervisory system, the monolithic integrated circuit control technology, the USB data acquisition technology with based on the TCP/IP agreement stack’s computer network structure organic synthesis, enables the people through to monitor video frequency audio frequency capture equipment and so on scene camera and microphone, will monitor the scene the signal through the local area network transmission, and delivers on the monitoring device to obtain the real-time image and the sound, thus realizes long-distance remote regards the scene.
Key word: Embedded system; Local area network; Real-time monitoring
Along with embedded system’s swift development, in many domains, is substituting gradually take the micro controller as the central application system take the computer as the central application. Therefore, regarding the network application system’s research, more and more researchers will study shifts with emphasis comes up to the embedded system. Based on this background, this article proposed one kind of network video frequency supervisory system plan, its goal is enables the people through to monitor video frequency audio frequency capture equipment and so on scene camera and Mike, will monitor the scene the signal through the local area network transmission, and delivers on the monitoring device to obtain the local real-time image and the sound, thus realizes the long-distance range remote to regard the scene.
System principle of work
In this monitoring plan, the embedded main engine system uses TI Corporation’s composite signal micro controller MSP430F1611 to take the system core controller, the USB host interface chip uses Cypress Corporation’s USB Host/Slave connection chip SL811HS, the ethernet transmission chip uses REALTEK Corporation’s fast ethernet control chip RTL8139, system’s constant voltage source chooses NS Corporation’s LM1117.
When system work, takes USB by MSP430F1611 and the SL811HS control from equipment’s camera, and reads in the video data, carries on processing and the memory to it. At the same time, reads in microphone’s in voice data MSP430F1611 to carry on the data conversion and the memory. Then, after the transmission level, the network level wrapped gift’s IP data newspaper will seal the ethernet frame by RTL8139, transmits on again the local area network after ethernet transformer PE68515.
System structure diagram
This plan overall system by the sound/video data gathering module, the sound/video data processing module, the ethernet transmission control module as well as the power source module four parts is composed, as shown in Figure 1.
Figure 1 system structure diagram
(1) sound/video data gathering module: This module mainly by the camera, the microphone and the peripheral circuit is composed. And the camera mainly by the lens, the image sensor and digital signal processing chip ZC0301P is composed, completes the image data gathering, the transformation and the transmission, the VGA video image transmission speed may reach each second 15. The microphone mainly uses in gathering the artificial voice signal.
(2) sound/video data processing module is mainly composed of MSP430F1611 and SL811HS, completes the data acquisition and processing. Embedded USB main/complies with the USB1.1 agreement from connection chip SL811HS and 16 monolithic integrated circuit MSP430F1611, with realizes the USB main engine function, and has the USB main line’s connection way. This module takes a data interface module to integrate the user in the embedded system, reads in the data to the camera and the microphone to carry on processes and saves.
(3) ethernet transmission control module: The primary mission is after the transmission level, the network level wrapped gift IP data newspaper carries on after RTL8139 the ethernet wrapped gift, after sealing the ethernet frame, transmits on the local area network through network transformer PE68515.
in (4) power source module basis system various components to power source’s request, causes the external power supply after the LM1117 manostat, to the system provides the 3.3V voltage.
System hardware design
In this design, the monolithic integrated circuit uses MSP430F1611, it has the 48KB 256B FLASH memory, 10KB RAM. MSP430F1611 and SL811HS mainly complete the system data acquisition and the processing function. MSP430F1611 and SL811HS hardware interface diagram as shown in Figure 2.
Figure 2 system hardware interface circuit diagram
In Figure 2, SL811HS M/S meets the low level, works under the main engine pattern. CM meets the low level, causes the system work in 48MHz. Both must be connected as a result of MSP430F1611 with SL811HS, and must be connected with RTL8139, but SL811HS pin itself non-three states of matter function, therefore needs to add three states of matter buffer 74HC244 between MSP430F1611 and SL811HS, achieves the three party service the goal. SL811HS meets MSP430F1611 through the buffer the I/O mouth; The interrupt request carries INTR0 to be directly connected with monolithic integrated circuit’s I/O mouth P1.1, after SL811HS transmits the data, has the high level output. Through monolithic integrated circuit timer check-out facility condition, if discovers from equipment turning on, then triggers the external interrupt.
The MSP430F1611 majority of pins take the I/O mouth, mainly uses for with SL811HS and the RTL8139 correspondence.
After MSP430F1611 and the RTL8139 correspondence’s function is transmits the upper formation application procedure the sound/video data which carries on processes and saves, carries on the data the seal process, will save data encapsulation UDP through the transmission level (User Datagram Protocol) the data packet, seals the IP data through the network level, as well as seals the ethernet frame through the data link layer, then transmits the destination through the physical network.
System software design
This design’s software part mainly includes the gathering module software design and the ethernet transmission module software design. Through monolithic integrated circuit timer check-out facility condition, if system discovery from equipment turning on, then triggers the external interrupt. After equipment discovery, carries on the equipment enumeration through SL811HS, establishes the device address, the data description and the disposition, then through large-scale memory agreement visit from equipment filing system.
Ethernet transmission module interrupt subroutine flow chart as shown in Figure 3. The RTL8139 data’s receive completes with the interrupt mode. When main processor to-line transmission data, delivers first 1 data through the DMA channel controller’s transmission buffer, then issues the transmission order, RTL8139 shifts according to PCI main line principal-mode -like the data from the transmission buffer to the interior transmits in FIFO. When in FIFO the data packet is complete, RTL8139 namely starts a package of transmission. The controller after the data transmission completes informs the main processor through the interrupt mode. When receives the data, on-line transmits the data packet is placed first receives in FIFO, simultaneously RTL8139 must carry on the address filtration. When receives in FIFO the data packet to achieve the receive disposes register’s request, RTL8139 requested that the PCI main line passes to according to the PCI pattern the data the receive buffer, after receiving full 1, similarly the interrupt mode informs main processor data receiving and dispatching the condition.
Conclusion
This design is mainly aims at lives in An Fang to apply proposed, the system may achieve finally the data transfer rate is 8~10Mbps. Is day by day common along with the network application and embedded system’s unceasing development, in the future will have more embedded network product production.
Reference:
1. Jiang Changjin. The network video frequency supervisory system’s research with realizes. Manufacturing industry automation, 2006.8
2.National Semiconductor Corp.LM1117 Data Sheet.2001
3.Texas Instruments.MSP430F1611 Data Sheet.2003.3
4.Cypress Semiconductor Corp.SL811HS Data Sheet.2002.3
5.Realtek Semiconductor Corp.RTL8139 Data Sheet.2001.11
