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Abstract: Superelevation frame frequency real-time image’s long sequence gathering saves the question which has been difficulty with solves. This article based on the SCSI main line’s system info, proposed that one kind of new image data gathering memory system’s technical program and the architecture, and design one kind supervelocity, digitized, the embedded system prototype. The test result indicated that in the multichannel simultaneously uses in the situation, gathering and the memory speed has achieved 100Mb/s, satisfied 1000 /s black and white digital images to save the hard disk technical requirement directly, has confirmed this system’s validity.
Key word: Supervelocity SCSI real-time stored image

Introduction

    At present, is getting bigger and bigger to high speed figure image’s gathering and the memory demand, but the majority this kind of systems rely on the fast microcomputer, the high speed image gathering card and the ultra large capacity memory. Satisfies these conditions to make the cost to advance doubled and re-doubled inevitably, the price is expensive, and it has a very big shortcoming is the capacity is young, even if uses the ultra large capacity memory, it increases the capacity which expands also only to be able to achieve several G byte magnitudes, if increases the capacity again, system’s volume and the cost have not permitted. Therefore, the application scope is restricted.

    (Redundant Arrays of Inexpensive Disks) the technical application is widespread day after day based on redundant floppy disk array RAID. Although it has used the floppy disk ultra large capacity, the volume exquisite superiority, has solved fast CPU and between slow floppy disk I/O through the floppy disk array architecture “the bottleneck” the difficulty, has served the high speed large capacity memory purpose; But its structure is complex, the floppy disk redundancy causes the cost to be high.

    To display each kind of technical fully the superiority, this article based on the SCSI main line’s system info, designs one kind as to save the carrier take the SCSI hard disk, controls supervelocity, digitization image data gathering and the memory system by the monolithic integrated circuit. Supervelocity is refers to be able real-time to save thousand per second video images, the data rate approximately is 100Mb/s; The digitization is refers to from the high speed camera’s output is the digitization, the memory also all for the digital quantity. It can be separated from the work which the microcomputer system and gathers completely alone saves, the simplicity of operator and practical. Below introduces this system from the technical program and the architecture.

First, system’s technical program and architecture

    Regarding supervelocity, the large capacity real-time video image memory system, the storage time and the speed are the technical specifications which wants high, but storage medium’s long time’s transmission speed, namely their continually transmission speed is also most important. Storage medium’s burst transmission speed and the internal transmission speed cannot take the real-time memory system’s weight target. Ordinary IDE connection hard disk, although its burst transmission speed and the bus transfer rate can above 33Mb/s, but in fact continually transmission speed 5Mb/s, far has not been able to meet the requirements. Comparatively, the SCSI hard disk’s continually transmission speed obviously is higher than the IDE connection hard disk. At present, 10000 revolution of SCSI hard disks continue transfer rate majority to be able to achieve 25Mb/s. If lets several SCSI hard disk multi-tasking, then the total transfer rate achieves 100Mb/s is achievable.

1.SCSI bus system and characteristic

    SCSI (Small Computer System Interface), namely the minicomputer system connection, is between the computer which and the peripheral device interface standard the American ANSI9.2 Committee defines. At first is by the floppy disk storage device primarily, but as a result of characteristics and so on its flexibility, equipment independence, enables SCSI not only at the magnetic tape equipment, the printing device, peripheral devices and so on CD-ROM WORM to obtain the universal application, also in many new I/O equipment and the computer network, domains and so on computer industrial control develops unceasingly. Figure 1 is the SCSI model system structure drawing.

    In the SCSI system, many equipment may use the identical electric cable to be connected. In 8 SCSI data line situation, may hang meets 8 peripheral devices; But present’s Ultera SCSI may achieve 32 bit data lines, can hang meets 32 peripheral devices. In the random time, can only two equipment be possible to correspond mutually, routing directive’s equipment is called the starting outfit (initiator), executive command’s equipment is called the goal equipment (target). On SCSI equipment’s only marking is SCSI ID, it is not only equipment’s address, is also the equipment priority code. In the SCSI operation is starts by the starting outfit, the starting outfit chooses a goal equipment first, after the goal unit select completes, the goal equipment obtains in the agreement to main line’s domination, is continues the control bus by the goal equipment decision to release the main line. Between the SCSI equipment has not advocated from the relations, an equipment already may become the starting outfit, may also the goal equipment’s function. On computer’s SCSI adapter is the typical starting outfit. The SCSI connection hard disk is typical Target. On the SCSI main line, may exist in many starting outfits and many goal equipment, but in a system should have a starting outfit and a goal equipment at least. Figure 1 is the typical multi-starting outfit multi-objective equipment system. In addition, but also has the list starting outfit multi-objective equipment, the list starting outfit simple target equipment. This article high speed data memory system uses the list starting outfit goal equipment system structure.

    The SCSI connection hard disk besides has above merit, its another characteristic was when marked the hard disk sector has used the linear concept, namely hard disk only then the 1st sector, the 2nd sector ……The n sector, does not look like the IDE hard disk “the cylinder/magnetic head/sector” three dimensional form. This kind of smooth arrangement sector address’s merit visits the time delay to be smallest, may speed up the hard disk access speed, especially in large capacity continues the data in the transmission, this linear arrangement’s way appears the superiority is obvious. If IBM the production DMVS-09V hard disk, it transmission speed may achieve 29.5Mb/s theoretically continually. The present operating system’s interior also uses the linear serial number the sector, its goal speeds up the medium access speed, enlarges the medium visit capacity.

    Although SCSI has it to be in sole possession of the characteristic, but the interface control is complex. Any SCSI system has the adapter and the controller appropriate match to the structure, usually the adapter is the starting outfit which above said. Adapter’s complexity lies in must realizes the SCSI equipment and each kind of operating system’s connection from the hardware and the software two parts. The software must complete SCSI the order explanation gives for the operating system and operating system’s operational order translator the SCSI equipment; The hardware must complete SCSI main line’s each kind of succession and internal circuit’s control.

2. system plan formulation

    According to the SCSI agreement, the news, the order, the data, the condition four stages are called as the information stage, this is because they are through the data bus transmission data and the control information. And the news, the order and the condition transmission uses the asynchronous system, data transmission available asynchronous and synchronized two ways.

    In the ideal situation, asynchronous transmits a byte only to need a system balanced time delay to add an electric cable to extend the time difference, it when is 45ns 4ns=49ns, in fact should consider the signal the jump when with the main line transmission time delay. The analysis believed that under the asynchronous system, transmits a byte to need 4 jumps to add on them on electric cable’s transmission time delay. Its model transmission time may calculate is

t=4×5.25×L 4×30

    And, t is byte transmission time, the unit is ns; L is the cable length, the unit is m. In the electric cable is in the 1m long situation, the transmission speed approximately is 7.1Mb/s.

    The synchronized transmission mechanism has introduced the synchronized displacement and the main line cushion concept, namely the goal equipment may send certain REQ signal continuously, but does not need starting outfit’s ACK to reply immediately. This greatly reduced the main line transmission time delay, thus raised the transmission speed. Therefore, this system carries on the design take 16 bit data synchronized transmission as the foundation.

    Unifies the above analysis, the real-time image data gathering memory system available SCSI hard disk takes the storage medium; Many SCSI hard disk multi-tasking in order to speed enhancement doubled and re-doubled; Image data’s gathering source selects the high speed figure camera, by thousand per second speed minute multi-channel output, each road’s data width may be 8 or 16. Redesigns the corresponding interface control electric circuit control software, in addition adjunct circuit constitution. Architecture as shown in Figure 2.

3. system’s architecture and functional description

(1) monolithic integrated circuit

Monolithic integrated circuit’s major function is as follows:

* carries on the translation, the execution, the management to the SCSI bus message condition;

* is responsible for between the main engine and the buffer, the buffer and the SCSI main line’s data transfer control;

* controls the DMA controller.

    Monolithic integrated circuit through buffer and SCSI interface control circuit switching information, including order description and condition news and so on. The monolithic integrated circuit is realizes to the SCSI main line’s control through the agreement controller. In order to complete a I/O advancement, the monolithic integrated circuit divides into the advancement stages and so on arbitration, choice, data transmission, and respectively gives the agreement controller execution by the corresponding internal control order.

(2) digital image interface circuit

    Mainly completes the video signal the digital conversion and the following logical control. Sometimes moreover, 8 data widths say regarding the following high speed memory duty are insufficient, must depend upon this electric circuit to transfer 16 bit wides or 32 bit wides.

(3) SCSI bus control unit

    This is the executive component which the SCSI main line operates, generally is called the adapter. The SCSI main line’s succession is very complex is also very orderly, the rule is refers to the SCSI main line to operate is composed of 8 independent main line stages, they respectively are: Main line free time, arbitration, choice, news, order, data feeds, data output and condition stage. Between them the migration has the strict stipulation, Figure 3 is the SCSI stage migration chart. The adapter accepts microprocessor’s operational order, like the arbitration, the choice, lose the company, the replacement main line and so on. The adapter is the starting outfit, is issues the order a side (under microprocessor control). The hard disk is the goal equipment, its response message and the returns condition and so on by the emblem processor analysis, and decide adapter’s next step the operation. Moreover, starts the I/O advancement, participates in the arbitration, the competition main line, the choice goal equipment and so on is by the microprocessor control operation.

(4) DMA controller

    In adapter’s DMA controller; first, between control image digital interface electric circuit and buffer’s data transfer; Second, controls between the buffer and the SCSI main line’s data transfer, may also through between the buffer positive governing image interface circuit and the SCSI main line’s data transfer.

Second, experimental result

    After system structure, produces the DDRS34560 hard disk and the DMVS-09V hard disk with IBM does the data transmission experiment, two kind of hard disk’s performance index like tables 1 arranges in order. The analysis transmits the 320MB data and 1GB data result like table 2 arranges in order.

Table 1

Table 2

    High speed camera outputs 955 /s with Canada’s DALSA Corporation’s CA-D6-256 260×260×8bit the video image, this system may real-time not have the compression parallel storage to many hard disks, the recorded time above 30min.

    The practice had proven this article elaborates the supervelocity real-time image storage system is can realize.