Key word: DSP USB feed pump condition monitor
1 introduction
Uses DSP (digital signal processor) to take the controller, but will use USB (universal serial bus) and the superior machine connects will be the data acquisition processing system’s one kind of possibility trend of development.
1.1 digital signal processor DSP
DSP chip, is also called the digital signal processor, is one kind is suitable specially in carries on the real-time digital signal processing the microprocessor, uses it to be able to satisfy the system computation load big request. Its main feature is: what (1) its interior uses is the procedure space and the data space separated Harvard structure, the permission simultaneously takes the instruction and takes the operand; in (2) chip uses the separation the bus structure, like this may guarantee in one cycle to be possible extremely many times the access routine space and the data space; (3) uses the running water line structure, takes in the program run refers to, the decoding, to take the operand and the execution phase overlaps; (4) chip interior includes many processing units generally, they may simultaneously carry on the operation in an instruction cycle; in the (5)DSP number system has established some special DSP instruction, can satisfy the digital signal processing application well the need; (6) instruction cycle is short, if the TMS320F240 instruction cycle may reach 50ns; (7) hardware disposes strongly, interface function, internal has the serial port, the host interface, the DMA controller, the phase-locked loop clock producer and in the piece simulation test access port and so on. DSP chip’s these characteristics, enable it to obtain more and more widespread application in each domain.
1.2 universal serial bus USB
USB (universal serial bus) the agreement is some PC big manufacturer one kind of serial communication standard which day by day to solve increases the PC peripheral device which and between the limited motherboard slot’s contradiction formulates. The USB connection is one fast, bidirectional, the synchronization, the low cost, the dynamic serial connection connection, supports the main engine and between the concurrent deposit peripheral device data exchange. The company peripheral device shares the USB band width through the main engine dispatch and based on the token agreement. The USB principal advantage includes: (1) speed is quick; (2) equipment disposition and the installment are easy. All USB equipment support hot drawing inserts, the system carries on the automatic disposition to it; (3) can use the main line power supply; (4) easy to expand; (5) use is flexible, USB altogether has 4 kind of modes of transmission: The control transmission, the synchronized transmission, the interrupt transmission, the block transmission, are suitable the different equipment’s need; (5) fault-tolerant, the USB agreement had stipulated meets mistake’s processing to each kind of possibility and restores the mechanism, had guaranteed data transmission’s accuracy, simultaneously, inserts processing to equipment’s hot drawing to be rapid, and does not interfere with system’s normal work; (6) realizes the cost to be low, USB has carried on the optimization to the system and the PC integration, suits in developing the low cost the peripheral device. As a result of these merits, the USB application scope is very broad.
The following this article will introduce one concrete based on DSP and USB technology digital gathering and the processing system feed pump running status observation system. This system needs carries on gathering to the feed pump movement process process quantity and the mechanical quantity, needs to carry on processing to the vibration signal, below introduces system’s principle of work, the system design, the hardware design and the software design separately.
2 system principle of work and system design
The feed pump running status observation system mainly completes each group mechanical quantity and process quantity gathering, and carries on the step to each vibration signal compared to the spectrum analysis, the computation vibration scope mean value, and will gather the data and the analysis result uploads PC machine, supplies feed pump’s running status information for the online overhaul system’s expert system; Simultaneously simply demonstrated that feed pump’s status messages, and provide the feed pump to vibrate the peak-to-peak value overstep and the axial translation overstep warning.
System’s characteristic is the computation load is big, the correspondence data quantity is big, moreover the feed pump running status monitor meter must provide the real-time condition data, this set the high request to timeliness. We use DSP according to system’s these characteristics (digital signal processor) USB (general serial interface) the plan to meet system’s need.
The feed pump condition observation system by the signal recuperation electric circuit, a/D switch, the DSP processor, SRAM, LCD, the keyboard as well as is composed based on the PLD connection and the logical control electric circuit. System’s system design diagram as shown in Figure 1.
3 system hardware designs
The system hardware part’s primary coverage including the DSP smallest system’s design, connection module’s design, the man-machine interface module’s design, recuperates electric circuit’s design and the power source module design.
DSP small system including reset circuit, clock circuit, SRAM connection, Flash memory connection and logical control electric circuit and so on. What here DSP controller selects is TMS320F240, it has the formidable peripheral device function, can for provide the high performance-to-price ratio based on the control application design the solution.
This system has used two kind of correspondence connections, respectively is USB and the RS232 connection. The USB connection uses in the measuring appliance to the PC machine upload data. The RS232 connection mainly uses in debugging and using in with the slow peripheral device connection, when the system upload’s data are not many may also use in the measuring appliance to the PC machine transmission data, like this may simplify the PC machine software’s design. Below carries on the introduction separately to these two connections.
3.1 RS232 connections
DSP in controller TMS320F240 includes a full-duplex’s serial interface, may very convenient realize the RS232 serial communication through the programming. The correspondence standard uses RS-232C. Here uses the MAX232 chip to complete the level switch work. The MAX232 chip is the low power loss which, the list 5V power source power supply MAXIM Corporation produces, the double RS232 transmission/receiver, it has the driving force, does not need in addition any driving circuit. Uses MAX232 serial communication interface circuit as shown in Figure 2.
3.2 USB connections
USB has completely namely inserts namely uses the characteristic, does not take the interrupt and so on system resources, provides many kinds of data transmission way as well as can achieve characteristics and so on high data transfer rate. Uses the USB connection to be possible to reduce system’s volume, reduces system’s power loss, causes the measuring appliance and system’s connection is more convenient.
Technically speaking, USB is a cable bus agreement, uses in the main engine with being possible to visit supporting facility’s data exchange. Through one token agreement which assigns by the main engine, the supporting facility shares USB the band width. A complete USB system is by the USB main engine, the concentrator, the tie cable and the USB peripheral device is composed. This article studies the feed pump running status monitor meter belongs to the USB peripheral device.
This article selects the USB correspondence chip is PDIUSBD12. It is a section of performance-to-price ratio very high component, usually uses in based on the MCU system, can through the high speed general parallel interface with the micro controller correspondence, simultaneously also support the local DMA transmission. PDIUSBD12 and TMS320F240 interface circuit as shown in Figure 3.
PDIUSBD12 and other common connection chip is the same, is also through reads in the control word to the chip to operate. First reads in a byte to the chip the order character, the notice chip processes the following data according to certain way, then to the chip read-write or a many byte’s data, the content which these data include possibly is the address, the data as well as some supposes the setting.
4 system software designs
This system uses C and the assembly mix programming, the master routine frame uses the C language establishment, the essential algorithm (for example FIR, FFT and so on) realize with the assembly language.
The feed pump running status monitors meter’s primary mission is: Completes the process quantity and mechanical quantity gathering, the filter, carries on the spectrum analysis to the mechanical quantity, will gather the data and the analysis result upload for PC machine, simultaneously, simply demonstrates feed pump’s running status information and so on.
Before we system design, background system, may also be called as for the ultra circulatory system. The application procedure is an infinite circulation, in the circulation transfers the corresponding function to complete the corresponding operation, this part may regard as the backstage behavior. The interrupt service processing asynchronous event, this part may regard as the onstage behavior. The backstage may also be called the duty level, the onstage also calls the interrupt level. The time relevance very strong key operation is certainly depending on the interrupt routine guarantee.
The daemon completes the function includes: Process quantity’s gathering and the filter, the axis inspires the sampling period the determination, and according to the sampling period initialization timer 0, FFT transformation, the data which and the analysis data after will gather places the transmission buffer, will wait the demonstration the information to read in the demonstration buffer, hands down from generation to generation the order to PC machine and the data message makes corresponding processing. Daemon’s flow chart as shown in Figure 4.
The onstage procedure mainly includes 3 timer interruptions and the keyboard interrupt servicing subroutine. The timer 0 interrupts, mainly use in the mechanical quantity data acquisition and the anti-aliasing filter; The timer 1 interrupt, is the RS232 serial communication provides the transmission metre; The timer 2 interrupts, provide the clock metre for monitor’s refurbishing; The keyboard interrupt, completes keyboard’s scanning and the gain key value. By timer 0 interrupt subroutine’s program flow diagram as shown in Figure 5.
5 concluding remark
Although this article take the feed pump as an example, but does not limit to the feed pump, replaces the signal recuperation board, is similarly suitable regarding other rotor machinery’s running status monitor. This system may also take the data acquisition and a processing general platform, has the broad application prospect.
