CN103207851A - Serial data real-time acquisition and time calibration method - Google Patents
Serial data real-time acquisition and time calibration method Download PDFInfo
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Abstract
The invention belongs to the field of data acquisition and provides a serial data real-time acquisition and time calibration method. An acquisition device comprises a base plate composed of serial data acquisition circuits and a core plate composed of digital signal processing (DSP) chips, wherein a global position system (GPS) module is added in the circuits of the base plate. The system base plate finishes a serial signal acquisition task and transmits acquired signal to the core plate. The core plate finishes data acquisition, data storage and time calibration processing tasks and adopts an dominant type software design concept and sets the priority level of universal asynchronous receiver and transmitter (UART) data acquisition to be highest, and other tasks are interrupted and an UART data acquisition task is carried out when data arrives. An internal real-time clock adopted by the method provides accurate time for a system and is composed of universal time coordinated (UTC) time and a timer. Acquired data and data acquisition time information are packed together, are temporarily stored in a device cache and can be uploaded to a personal computer (PC) to be stored in real time, and the time calibration accuracy can reach to +/-0.2ms.
Description
Technical field
The invention belongs to data collecting field, is that a kind of signal processing technology, computer technology, DSP technology, GPS Service of Timing etc. utilized realize that serial data is gathered in real time and the method for timestamp.This method can satisfy the parallel of four-way serial data simultaneously and gather in real time, and each the byte data mark that can be reception is gathered the instantaneous time, image data is packed with this data acquisition time information and is temporarily stored in the equipment buffer memory, and can be uploaded to the PC preservation in real time, the timestamp precision can reach ± 0.2ms.
Background technology
The task of data acquisition system (DAS) is the simulating signal of gathering different occasions.This task has two steps: at first by A/D converter, the simulating signal that collects is converted into the digital signal that computing machine can identify and is input in the computing machine.Then, computing machine carries out display analysis to data, thereby has reached the purpose that corresponding physical quantity is monitored.
But in some particular application, needing to be distributed in the data that the data acquisition equipment of diverse location collects compares, analyze the corresponding relation of input information and output information, because the data zero-time that each collecting device collects is not quite similar, and the interface type of data acquisition, baud rate etc. is inconsistent, makes the input information that collects and the corresponding relation of output information be difficult to determine.Utilization of the present invention is to the method for each byte data mark real-time time of collecting, solves the corresponding relation of input data and output data by the consistance of image data time relatively.The data markers time adopts GPS to unify the UTC time of time service, is convenient to the data that will collect and time and other equipment and collects to such an extent that data compare between timely.
Gps satellite sends self ephemeris parameter and temporal information incessantly to the user, and it is not only traditional high precision GPS, also is high-precision real-time time signal source.The GPS receiver receives the time information data of satellite emission, according to NMEA protocol analysis data, comprises information such as UTC time, longitude, latitude, height above sea level.Receiver has an output terminal to export the 1pps(pulse per second (PPS) specially in addition) signal, its pulse width is generally in the ms magnitude.The high level rising edge is the accurate moment of pulse per second (PPS) output, the UTC time of corresponding receiver serial ports output, is no more than 1us with the maximum error of standard time.
Summary of the invention
The present invention is different from common data collector, outstanding feature of the present invention: increased the GPS module on the basis of general data Acquisition Circuit, UTC time that is provided by the GPS module and pps pulse per second signal is carried out frequency division internal time is provided, can be each the byte data mark real-time time that collects.
The present invention is made up of data collector, system under test (SUT) and peripherals.Technical scheme of the present invention is referring to Fig. 1, Fig. 2.System connects referring to Fig. 1, and this system forms a sets of data acquisition system by system under test (SUT), data collector, peripherals etc., and peripherals comprises gps antenna, power supply, electrooptic conversion module and PC.The power supply of data acquisition system adopted civil power 5V adapter.Data collector internal hardware design proposal adopts core board to add the structural design of base plate referring to Fig. 2, and core board couples together by DDR2 notebook memory bar slot SODIMM200 and base plate.Base plate is mainly peripheral Acquisition Circuit, is used for receiving serial signal, comprises RS232/RS485/RS422/ optical fiber interface, power module, GPS module, MUX, UART agreement selection circuit etc.The core version is selected dsp processor Blackfin548 for use, uses its four road UART interfaces that carry to link to each other with serial information interface on the base plate and receives external information.Select circuit by the UART agreement on the base plate, can select different communication protocol, as RS232, RS485, RS422 or optical fiber; The IIC interface that uses core board to carry receives the NMEA protocol information of GPS, resolves the UTC time; Use interrupt pin to receive pps pulse per second signal, proofread and correct inner frequency division timer; Use the USB2.0Client interface on the core board to connect PC, by PC control collector duty, and the information of gathering uploaded to preserved in the PC and handle.The invention is characterized in that this method also comprises following method successively:
Serial data is gathered the timestamp method in real time, it is characterized in that: harvester comprises the base plate of serial data collection circuit formation and the core board that dsp chip constitutes, and adds the GPS mould in backplane circuit.This method is specific as follows:
System backplane is finished the serial signal acquisition tasks, and will gather signal and be sent to core board: at first select different interface type (RS232/RS485/RS422/ optical fiber interface) on the base plate according to system under test (SUT) communication protocol, then by the communication protocol gating the corresponding interface type of gate control circuit according to selection, for preventing that external serial signal is to interfering with each other between the influence of the core circuit of equipment and the serial data, adopt the method for designing of signal isolation and isolated from power, data are sent to core board at last again through buffer circuit.
Core board is finished acquired data storage and timestamp Processing tasks, and core board is selected the Blackfin548DSP processor for use.At first, 4 road UART information of using core board to carry are directly connected four road serial ports, have improved the speed that receives data under the condition of assurance data acquisition reliability; Secondly; The be dominant software design idea of formula of employing, the priority of setting the UART data acquisition is the highest, and when data arrive, any other task all will be interrupted and be carried out UART data acquisition task.At last, according to the internal system time, be that timestamp is preserved together on the data markers in the moment of finishing every byte data collection.
The inside real-time clock of this method provides precise time for system: inner real-time clock is made of UTC time and timer two parts.At first, the IIC interface that uses core board to carry receives the NMEA protocol information of GPS, parses the UTC time, the time of instant, minute, second one-level; Secondly, use the external interrupt pin to receive pps pulse per second signal, guarantee the accuracy of pps pulse per second signal; Then, adopt frequency splitting technology, pulse per second (PPS) is divided into 5000-10000 part, namely set 0.1-0.2 millisecond timer, millisecond counter is added to behind the 5000-10000 automatic clear and begins cycle count down by 1; Then, use pps pulse per second signal per second calibration timer, eliminate the crystal oscillator drift to the influence of inner clock accuracy; At last, UTC time and timer time are formed the internal system clock jointly, be its mark timestamp when every byte data collection is finished, the timestamp precision is ± the 0.2-0.4 millisecond.
The present invention is because of the problem of existing equipment precision, so pulse per second (PPS) is divided into 5000-10000 part, too high equipment precision is difficult to reach; Cross to hang down and to embody advantage of the present invention.
The method that the present invention adopts UTC time that GPS provides and pps pulse per second signal to proofread and correct the frequency division temporal information in real time provides the internal system temporal information.At first, use the UTC time that receives that be provided reference time, time format is hh:mm:ss, and the time can be accurate to a second one-level.Then, adopt frequency splitting technology by equipment DSP timer internal whole second to be split, the time that is accurate to Millisecond is provided.At last, the two is synthesized system time, and utilize the GPS pulse per second (PPS) that the internal system timer is proofreaied and correct in real time, guarantee time precision.
Description of drawings
Fig. 1 is systematic schematic diagram;
Fig. 2 is the The Hardware Design scheme;
Fig. 3 is the serial data collection circuit;
Fig. 4 is internal time composition principle figure;
Fig. 5 is millisecond counter calibration synoptic diagram;
Fig. 6 is the system data flow diagram;
Fig. 7 is that double buffering replaces the preservation mode fundamental diagram.
Embodiment
Need in the invention process equipment under test, data acquisition equipment (comprising power supply, gps antenna, usb data line etc.), PC are linked to each other, can realize real-time collection and the timestamp of data behind the starting outfit, and with the data upload of gathering to PC, for the follow-up comparative analysis use of data.
In concrete the enforcement, referring to Fig. 1, at first fibre-optical splice (or RS485/422/RS232 Serial Port Line) and equipment under test are connected, another joint is connected to passage " Ch1 ", " Ch2 ", " Ch3 " and " Ch4 " (referring to Fig. 2) successively; Secondly gps antenna is connected to the GPS interface; Then power supply adaptor is connected to power interface, and turns on the power switch; At last usb data line one is connected to collecting device, the other end links to each other with PC (host computer), opens the PC runnable interface, selects suitable passage, interface type, baud rate etc. can begin image data.
System backplane is mainly finished the serial signal acquisition tasks.Mainly be the serial data collection circuit on the base plate, referring to Fig. 3.This method has three steps:
Step a: select different interface type (RS232/RS485/RS422/ optical fiber interface) on the base plate according to system under test (SUT) communication protocol;
Step b: 1. the data of each interface collection are input to the input gating circuit by different level transferring chip; 2. import gating circuit and controlled by gate control circuit, synchronization has only a kind of interface type path to be strobed;
Step c: 1. for preventing external serial signal to phase mutual interference between the influence of the core circuit of equipment and the serial signal, image data is sent to core board again by the input gating circuit behind buffer circuit; 2. buffer circuit mainly is divided into signal and isolates and isolated from power two parts the isolation of system's use photoelectrical coupler realization signal; Use No. four isolating transformers, isolate four the tunnel independently the 5V power supply give the power supply of four tunnel Acquisition Circuit respectively.
2) core board is mainly finished acquired data storage and timestamp Processing tasks, and this method comprises three steps:
A. 4 road UART information of using core board to carry are directly connected four road serial ports, have improved the speed that receives data under the condition of assurance data acquisition reliability;
B. system software adopts the design philosophy of the formula that is dominant, and the priority of setting the UART data acquisition is the highest, and when data arrive, any other task all will be interrupted and carry out UART data acquisition task.
C. according to the internal system time, be that timestamp is preserved together on the data markers in the moment of finishing every byte data collection.
3) the inside real-time clock of this method provides precise time for system.Inner real-time clock is made of UTC time and timer two parts, referring to Fig. 4.This method comprises following three steps:
A. system's IIC interface of using core board to carry receives the NMEA protocol information of GPS, parses the UTC time, the time of instant, minute, second one-level;
B. the time of Millisecond is adopted frequency splitting technology, obtains by inner 0.1 millisecond of timer simulation real-time clock, trigger the initial of millisecond timer by the GPS pps pulse per second signal, and per second is calibrated.Step b comprises: 1. system uses the internal timing mode of operation simulated interior real-time clock that core board provides, and sets 0.1 millisecond of interruption once, and interrupt service routine makes millisecond counter after add 1, being added to 10000, and the millisecond counter zero clearing begins cycle count down; 2. for eliminating the crystal oscillator drift to the influence of inner clock accuracy, adopt the pps pulse per second signal rising edge calibration internal clocking of GPS module output in the system, the error of accumulation in a second is eliminated when next second begins, can not produce accumulative total.Under normal circumstances, millisecond counter count down to 10000, is the moment that pulse per second (PPS) produces just, does not need to revise internal time this moment.Under different situations, be different by the caused error of crystal oscillator, referring to Fig. 5, under unusual 1 situation, the actual frequency overgauge frequency of crystal oscillator, then counter count down to 10000 in advance, in next pulse per second (PPS) arrives, with counter O reset and restart counting.Under unusual 2 situation, the actual frequency of crystal oscillator is less than standard frequency, and when pulse per second (PPS) was arrived, counter had only count down to 9999.Identical with unusual 1, pulse per second (PPS) can only accumulate timing error the counter O reset New count of laying equal stress in 1 second.3. use the external interrupt pin to receive the accuracy that pps pulse per second signal guarantees pps pulse per second signal.
4) in the system, by the RTC(real-time clock of image data from UART mouth and inside) flow to SDRAM, after in SDRAM, gathering, be uploaded to PC through USB again, referring to Fig. 6.Operation will be imported, exports and be preserved to data at this node of SDRAM, and frequent the generation.For avoiding data collision, adopt double buffering to replace preservation mode, open up two buffer zones, one receives the data that UART and RTC send, and another transmits data by USB to PC, with the operand of input and output separately.Referring to Fig. 7, the data stream of UART and RTC and the data stream of USB do not share same buffer zone, and its corresponding buffer region also is unfixed, it is not necessarily corresponding Buffer1 operation always of UART and RTC, and also not necessarily corresponding Buffer2 operation always of USB, " going into " and " going out " corresponding buffer zone replaces.
Claims (1)
1. serial data is gathered the timestamp method in real time, it is characterized in that: harvester comprises the base plate of serial data collection circuit formation and the core board that dsp chip constitutes, and adds the GPS mould in backplane circuit; This method is specific as follows:
System backplane is finished the serial signal acquisition tasks, and will gather signal and be sent to core board: at first select different interface type on the base plate according to system under test (SUT) communication protocol, then by the communication protocol gating the corresponding interface type of gate control circuit according to selection, adopt the method for designing of signal isolation and isolated from power, data are sent to core board at last again through buffer circuit;
Core board is finished acquired data storage and timestamp Processing tasks: at first, 4 road UART information of using core board to carry are directly connected four road serial ports; Secondly, adopt the software design idea of the formula that is dominant, the priority of setting the UART data acquisition is the highest, and when data arrive, any other task all will be interrupted and carry out UART data acquisition task; At last, according to the internal system time, be that timestamp is preserved together on the data markers in the moment of finishing every byte data collection;
The inside real-time clock of this method provides precise time for system: inner real-time clock is made of UTC time and timer two parts: at first, the IIC interface that uses core board to carry receives the NMEA protocol information of GPS, parse the UTC time, the time of instant, minute, second one-level; Secondly, use the external interrupt pin to receive pps pulse per second signal, guarantee the accuracy of pps pulse per second signal; Then, adopt frequency splitting technology, pulse per second (PPS) is divided into 5000-10000 part, namely set 0.1-0.2 millisecond timer, millisecond counter is added to behind the 5000-10000 automatic clear and begins cycle count down by 1; Then, use pps pulse per second signal per second calibration timer, eliminate the crystal oscillator drift to the influence of inner clock accuracy; At last, UTC time and timer time are formed the internal system clock jointly, be its mark timestamp when every byte data collection is finished, the timestamp precision is ± 0.2-0.4ms.
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| CN104423417A (en) * | 2013-08-26 | 2015-03-18 | 上海工程技术大学 | Synchronous phasor precise timing system |
| CN104991469A (en) * | 2015-05-19 | 2015-10-21 | 广东中鹏热能科技有限公司 | Equipment data preferential collection method and system |
| CN105350956A (en) * | 2014-08-22 | 2016-02-24 | 中国石油化工股份有限公司 | Microseism data acquisition real-time monitoring system and method thereof |
| CN105372698A (en) * | 2015-10-13 | 2016-03-02 | 中国石油天然气集团公司 | Interface gating module, seismic data acquiring station based on same and communication method |
| CN105700343A (en) * | 2016-04-07 | 2016-06-22 | 飞亚达（集团）股份有限公司 | Long duration monitoring device and method for reference UTC time source |
| CN105720986A (en) * | 2016-01-22 | 2016-06-29 | 山西大学 | Multi-channel data collection system with unified time stamp |
| CN106656451A (en) * | 2016-12-29 | 2017-05-10 | 中国科学院西安光学精密机械研究所 | Time-keeping and timing precision test device, time-keeping precision test method and timing precision test method based on satellite timing system |
| CN106773985A (en) * | 2016-12-29 | 2017-05-31 | 西北核技术研究所 | A kind of high accuracy sequence control unit and method for remote multiparty control |
| CN106850115A (en) * | 2017-03-07 | 2017-06-13 | 中国地质大学（武汉） | A kind of Multi-channel data acquisition synchronization system and method |
| CN108768576A (en) * | 2018-06-29 | 2018-11-06 | 广东星舆科技有限公司 | A kind of method and device obtaining sensor precise synchronization data |
| CN109039515A (en) * | 2018-07-24 | 2018-12-18 | 北京新宇航星科技有限公司 | A kind of high-precision real-time time source generation method that B code is synchronous |
| CN109617641A (en) * | 2018-12-04 | 2019-04-12 | 中国航空工业集团公司西安航空计算技术研究所 | A kind of adjustable accuracy time obtaining method based on pulse per second (PPS) |
| CN110647489A (en) * | 2019-09-12 | 2020-01-03 | 上海鲍麦克斯电子科技有限公司 | High-speed communication method and communication system for monitoring serial port |
| CN110908272A (en) * | 2019-12-20 | 2020-03-24 | 昆明理工大学 | 1pps pulse signal timing method |
| CN111208539A (en) * | 2019-12-18 | 2020-05-29 | 中国航空工业集团公司成都飞机设计研究所 | High-precision GNSS simulator time synchronization method |
| CN111970077A (en) * | 2020-08-13 | 2020-11-20 | 中国科学院国家天文台 | High-precision absolute time and system synchronization method for detector reading system |
| CN111988105A (en) * | 2020-08-25 | 2020-11-24 | 烟台东方威思顿电气有限公司 | RS 485-based high-precision time synchronization method |
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| CN104423417A (en) * | 2013-08-26 | 2015-03-18 | 上海工程技术大学 | Synchronous phasor precise timing system |
| CN105350956A (en) * | 2014-08-22 | 2016-02-24 | 中国石油化工股份有限公司 | Microseism data acquisition real-time monitoring system and method thereof |
| CN104991469B (en) * | 2015-05-19 | 2017-08-01 | 广东中鹏热能科技有限公司 | A kind of device data preferential collection method and system |
| CN104991469A (en) * | 2015-05-19 | 2015-10-21 | 广东中鹏热能科技有限公司 | Equipment data preferential collection method and system |
| CN105372698A (en) * | 2015-10-13 | 2016-03-02 | 中国石油天然气集团公司 | Interface gating module, seismic data acquiring station based on same and communication method |
| CN105720986A (en) * | 2016-01-22 | 2016-06-29 | 山西大学 | Multi-channel data collection system with unified time stamp |
| CN105720986B (en) * | 2016-01-22 | 2019-04-05 | 山西大学 | Multi-path data acquiring system with unified time mark |
| CN105700343A (en) * | 2016-04-07 | 2016-06-22 | 飞亚达（集团）股份有限公司 | Long duration monitoring device and method for reference UTC time source |
| CN105700343B (en) * | 2016-04-07 | 2018-06-29 | 飞亚达（集团）股份有限公司 | Benchmark UTC time source long duration monitoring device and its method |
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| CN106850115A (en) * | 2017-03-07 | 2017-06-13 | 中国地质大学（武汉） | A kind of Multi-channel data acquisition synchronization system and method |
| CN108768576A (en) * | 2018-06-29 | 2018-11-06 | 广东星舆科技有限公司 | A kind of method and device obtaining sensor precise synchronization data |
| CN109039515A (en) * | 2018-07-24 | 2018-12-18 | 北京新宇航星科技有限公司 | A kind of high-precision real-time time source generation method that B code is synchronous |
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| CN109617641B (en) * | 2018-12-04 | 2021-10-26 | 中国航空工业集团公司西安航空计算技术研究所 | Adjustable precision time obtaining method based on pulse per second |
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| CN110908272A (en) * | 2019-12-20 | 2020-03-24 | 昆明理工大学 | 1pps pulse signal timing method |
| CN110908272B (en) * | 2019-12-20 | 2021-04-13 | 昆明理工大学 | 1pps pulse signal timing method |
| CN111970077A (en) * | 2020-08-13 | 2020-11-20 | 中国科学院国家天文台 | High-precision absolute time and system synchronization method for detector reading system |
| CN111970077B (en) * | 2020-08-13 | 2023-03-10 | 中国科学院国家天文台 | High-precision absolute time and system synchronization method for detector reading system |
| CN111988105A (en) * | 2020-08-25 | 2020-11-24 | 烟台东方威思顿电气有限公司 | RS 485-based high-precision time synchronization method |
| CN111988105B (en) * | 2020-08-25 | 2022-11-01 | 烟台东方威思顿电气有限公司 | RS 485-based high-precision time synchronization method |
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Application publication date: 20130717 |