NI PCI-5153EX. Contents USER GUIDE. with Hardware Accumulation Firmware

Transcription

1 USER GUIDE NI PCI-5153EX with Hardware Accumulation Firmware Contents The National Instruments PCI-5153EX is a version of the NI PCI-5153 that has a higher capacity FPGA. The larger FPGA enables the NI PCI-5153EX to implement additional onboard signal processing. The Hardware Accumulation Firmware image (FW06) is a set of code that can be downloaded to the NI PCI-5153EX FPGA to add hardware accumulation functionality to the device. This document describes the additional functionality of the NI PCI-5153EX with FW06 firmware. For other information about the device, refer to the NI High-Speed Digitizers Help. Specifications... 2 Hardware Block Diagram... 2 Onboard Signal Processing... 3 Data Inversion Circuit... 3 Threshold Circuit and Digital Offset... 4 Waveform Accumulation... 6 Glossary... 8 Programming... 9 NI 5153EX Supplemental Software... 9 Features... 9 Examples... 9 Programming Flow... 9 Creating an Application LabVIEW C/C Niscope Averager Programming Reference Niscope Averager Enable Onboard Averaging Niscope Averager Configure Noise Suppression Binary Niscope Averager Commit Niscope Averager Fetch Average Niscope Averager Fetch Binary Average... 17

2 Specifications Hardware Block Diagram The following documents contain the detailed product specifications for the NI 5153EX: NI 5153/5154 Specifications NI PCI-5153EX with Hardware Accumulation Firmware (FW06) Specifications Supplement The following figure shows a detailed block diagram of the NI PCI-5153EX digitizer. Refer to the NI High-Speed Digitizers Help for more information about the features of the NI PCI Dual ADCs CH 0 CH 1 AC/DC Coupling AC/DC Coupling Analog In Path Analog In Path 8-Bit 1 GS/s ADC TIS Mode 8-Bit 1 GS/s ADC Decimation/ Onboard Signal Processing Onboard Memory PCI Interface PCI Bus TRIG DC Coupling TRIG In Path Trigger and Event Control Acquisition Engine PFI 0 Clocking RTSI 7 PFI 1 Sample Clock Reference Clock RTSI Bus Signal Routing Matrix RTSI <0..6> RTSI 7 Figure 1. NI PCI-5153EX Block Diagram NI PCI-5153EX User Guide 2 ni.com

3 Onboard Signal Processing The following diagram shows the onboard signal processing blocks of the Hardware Accumulation Firmware (FW06). Waveform Accumulation Deep Onboard Memory FPGA PCI ADC ADC Data Inversion Data Inversion Threshold/ Digital Offset Threshold/ Digital Offset Partial Sums Combine Partial Sums PCI Interface Data Inversion Circuit Figure 2. NI PCI-5153EX Onboard Signal Processing Block Diagram The Data Inversion circuit allows the user to invert the polarity of the data. That is, for each sample, i, in the input record w, Data Inversion transforms the record as shown in the following graphs. Figure A shows the original signal; Figure B shows the signal after applying Data Inversion. A B National Instruments Corporation 3 NI PCI-5153EX User Guide

4 Threshold Circuit and Digital Offset The threshold circuit allows you to remove unwanted information from the record by setting a programmable threshold level. If data inversion is disabled, samples at or below Threshold are set to a programmable ThresholdFloor value. If data inversion is enabled, samples at or above the Threshold are set to the programmable ThresholdFloor value. If digital offset is enabled, samples not set to ThresholdFloor are offset by a constant value. Figures 3 5 show examples of how the Threshold/Digital Offset circuitry works. Figure 3. Input Waveform NI PCI-5153EX User Guide 4 ni.com

5 Figure 4. Output of Threshold Circuit Figure 5. Output of Threshold Circuit with a Negative Digital Offset Value National Instruments Corporation 5 NI PCI-5153EX User Guide

6 Waveform Accumulation The following pseudocode further illustrates how the Threshold/Digital Offset circuitry works. For each sample i in the input record w, the threshold circuit and the digital offset transform the records as follows (assuming that data inversion is disabled): if ThresholdIsEnabled if w[i] = Threshold w[i] = ThresholdFloor else if DigitalOffsetIsEnabled w[i] = w[i] + DigitalOffset endif else if DigitalOffsetIsEnabled w[i] = w[i] + DigitalOffset endif The waveform accumulation circuit generates a multi-record sum by performing a sample-by-sample sum of each record. The host PC can divide the sums by the number of records to generate an average waveform. Conceptually, this circuit contains a set of 24-bit accumulators one accumulator for each sample in a record. For each record w, for each sample i, in the record, the value of the sample is summed with the sum of sample i from all of the previous records in the current acquisition. That is, the accumulator for sample i (acc[i]) changes as follows: acc[i] = acc[i] + w[i] NI PCI-5153EX User Guide 6 ni.com

7 For two-channel applications, each channel is accumulated independently. The following figure illustrates waveform accumulation. Record Record Record Record Sample Sample Σ Σ Each Element i Is The Sum Of Element i From Each Record Multi-record sum Figure 6. Waveform Accumulation Note When using a Reference trigger to control when records are acquired, to accumulate N desired records, you must provide N+1 triggers. The final trigger flushes the sum data. National Instruments Corporation 7 NI PCI-5153EX User Guide

8 Glossary Figure 7 illustrates the definitions of several terms. Block Deadtime Block Record Rearm time Record Rearm time Record Sample Trigger Sample Period = 1 Sample Rate Figure 7. Terminology Sample: one A/D conversion. Sample Period: the time between two consecutive samples. Sample Rate: 1/Sample Period. Record: a set of samples taken consecutively in time in response to a trigger. Rearm time: the minimum time between the last sample of a record and when the device is able to recognize a trigger for the following record. Block: a set of records (all with the same number of samples) taken consecutively in time. Deadtime: the minimum time between the last sample of the last record of a block and the first sample of the first record in the following block. Multi-record Sum: a record where each element i is the sum of element i from each record in a block. Refer to Figure 6 in the Waveform Accumulation section for more information. NI PCI-5153EX User Guide 8 ni.com

9 Programming NI 5153EX Supplemental Software The use of the accumulation feature on the NI PCI-5153EX requires using supplemental software called Niscope Averager. This section describes how to use Niscope Averager software to control the accumulation firmware feature of the device. The Niscope Averager software works with the NI-SCOPE instrument driver and does not replace it. Features Onboard accumulation of multiple records to form one multi-record sum that can be fetched back to the host by the user, either as a binary sum or an averaged voltage Onboard data inversion Threshold/digital offset Examples Examples are included with the software download. Programming Flow The programming flow for using the accumulation feature of the device uses standard NI-SCOPE function calls in conjunction with Niscope Averager function calls. Figure 8 illustrates a standard programming flow. National Instruments Corporation 9 NI PCI-5153EX User Guide

10 NI-SCOPE Initialize NI-SCOPE Configure Niscope Averager Configure Niscope Averager Commit Niscope Averager NI-SCOPE Enable Initiate Onboard Acquisition Averaging NI-SCOPE Initiate Acquisition Niscope Averager Fetch Functions No Do More Acquisitions? Yes NI-SCOPE Close Figure 8. Programming Flow for Averaging You must call Niscope Averager Enable Onboard Averaging before starting every acquisition, even if you are not changing any configurations. NI PCI-5153EX User Guide 10 ni.com

11 Note After you enable onboard averaging the only way to disable it is to call NI-SCOPE Device Reset. You must call NI-SCOPE Device Reset if your application switches between averaging mode and normal mode. Creating an Application LabVIEW 1. Launch LabVIEW. 2. Open an existing LabVIEW VI or create a new VI. 3. Make sure you are on the block diagram screen. 4. Launch the NI-SCOPE palette. 5. Build your application using the Niscope Averager functions in the appropriate programming flow steps. C/C++ To create an application follow the NI-SCOPE directions, which are available in the NI High-Speed Digitizers Help. In addition, you must include the following Niscope Averager files in your application: niscopeavg.h niscopeavg.lib niscopeavg.dll To build the examples in Microsoft Visual C using the Microsoft NMAKE utility, complete the following steps: 1. Go to the directory for the particular example you want to use. 2. Run the VCVARS32.BAT batch file (located in the \bin directory of the MSVC compiler) to set up the environment variables for command line usage if they are not already set. You may need to increase the initial environment size of the DOS box to accommodate the added environment variables. 3. To build an example, run nmake examplename.mak. The executable is built to the debug subdirectory by default. National Instruments Corporation 11 NI PCI-5153EX User Guide

12 Niscope Averager Programming Reference The following reference for Niscope Averager is an extension of the NI-SCOPE programming reference, which can be found in the NI High Speed Digitizers Help. Niscope Averager Enable Onboard Averaging Purpose This function enables the onboard averaging functionality. The function disables the TDC and sets the reference position to zero. After you enable this function you can no longer use NI-SCOPE Fetch functions; use Niscope Averager functions instead. Call this function after you complete all your configurations (right before you call NI-SCOPE Initiate Acquisition). Call this function prior to every acquisition, even if no configurations have changed. Note After you call this function you can only disable averaging mode by calling NI-SCOPE Device Reset. Function Prototypes C Function ViStatus niscopeavg_enableonboardaveraging (ViSession vi, ViInt32 numberofaverages, ViInt32* actualnumberofrecords, ViInt32* numberofpartialsums); LabVIEW VI Parameters vi Name numberofaverages Description The instrument handle you obtain from niscope_init that identifies a particular instrument session. The number of records that the averaging firmware should accumulate. NI PCI-5153EX User Guide 12 ni.com

13 Niscope Averager Configure Noise Suppression Binary Purpose This function configures the noise suppression onboard signal processing. Noise suppression consists of two blocks: Data Inversion and Threshold Circuit/Digital Offset. You can enable and configure each block individually using this function. The parameters are specified in signed binary 8-bit values and correspond to the uncalibrated binary data from the ADC. Each configuration of a device has specific calibration coefficients to scale uncalibrated binary data to volts. These coefficients are determined for each configuration of each device during a calibration operation and then programmed into the device. NI-SCOPE binary functions and Niscope Averager binary functions use or return raw binary data without applying these coefficients. When using binary functions, your application must apply the coefficients if you want calibrated data. If you are using NI-SCOPE 3.6 or later, you can use the VI/function niscope Get Scaling Coefficients to retrieve the scaling coefficients for your desired configuration 1. After you obtain the offset and gain coefficients for the particular configuration and device, you can determine the binary code corresponding to the desired voltage by solving the following formula for binary data: voltage = binary data * gain factor + offset The corresponding binary codes for the desired Threshold, Threshold Floor and Digital Offset voltages should be provided to this function as part of the configuration of the desired acquisition so that the noise suppression functionality applies the calibration coefficients of the device. Note that while noise suppression configuration is only offered as a binary function, you can use fetch functions that return either binary or scaled data. For further information, refer to any binary fetch function in the NI-SCOPE Function Reference Help or the NI-SCOPE LabVIEW Reference Help. Threshold Floor and Digital Offset limits are shown in the following table. Description Max Value Min Value Threshold Floor Threshold Full Scale Digital Offset 0 Threshold Floor Threshold 1 If you are using NI-SCOPE versions or to obtain the coefficients for the desired configuration of a particular device in the system, first run a dummy acquisition with all desired analog front end configuration settings, then call a fetch function. One of the return values of the fetch functions is a wfm info struct that includes the offset and gain coefficients required to convert between ADC codes and calibrated voltage. National Instruments Corporation 13 NI PCI-5153EX User Guide

14 Note The configuration is not applied to hardware until you call niscopeavg Commit. Function Prototypes C Function ViStatus niscopeavg_configurenoisesuppressionbinary (ViSession vi, ViConstString channel, ViBoolean invertsamplesenable, ViBoolean thresholdenable, ViInt32 threshold, ViInt32 thresholdfloor, ViBoolean digitaloffsetenable, ViInt32 digitaloffset); LabVIEW VI Parameters Name vi channel invertsamplesenable thresholdenable threshold thresholdfloor digitaloffsetenable digitaloffset Description The instrument handle you obtain from niscope_init that identifies a particular instrument session. The channel from which to acquire data. Enables the Data Inversion OSP block. Enables the Threshold OSP block. Specifies the ADC binary level to apply a threshold to. All samples at or below this level will be replaced with the threshold floor. The binary value to replace samples below the threshold Enables the Digital Offset OSP block. Specifies the offset in ADC binary codes to offset the data. NI PCI-5153EX User Guide 14 ni.com

15 Niscope Averager Commit Purpose This function applies the user configuration to hardware. Call this function after you finish configuring the device, but before you call NI-SCOPE Initiate Acquisition. Function Prototypes C Function ViStatus niscopeavg_commit (ViSession vi); LabVIEW VI Parameters vi Name Description The instrument handle you obtain from niscope_init that identifies a particular instrument session. Niscope Averager Fetch Average Purpose This function fetches scaled averaged data from the onboard memory of the device. The function works similarly to other NI-SCOPE functions. This function does not support fetching relative to any other location than pretrigger. The function begins fetching the averaged data after the acquisition is complete. Data allocation in C is different for this function compared to standard NI-SCOPE function calls. The allocation code is as follows: niscope_actualrecordlength(vi, &actualrecordlength) waveformptr = malloc (sizeof (ViReal64)* actualrecordlength); The Niscope Averager fetch functions cannot take more than one channel per fetch call. To fetch multiple channels you must call the function multiple times, using one channel name per call. National Instruments Corporation 15 NI PCI-5153EX User Guide

16 Function Prototypes C Function ViStatus niscopeavg_fetchavg (ViSession vi, ViConstString channel, ViReal64 timeout, ViInt32 numpts, ViInt32* actualnumberofrecordsaccumulated, ViReal64* wfm, struct niscope_wfminfo* wfminfo); LabVIEW VI Parameters Name vi channel timeout numpts actualnumberofrecordsaccumulated wfm wfminfo Description The instrument handle you obtain from niscope_init that identifies a particular instrument session. The channel from which to acquire data. The amount of time, in seconds, the function should wait for the data before returning an error. The number of points to fetch from the device. The actual number of records accumulated. The waveform data. The waveform information, including calibration constants and timestamps. NI PCI-5153EX User Guide 16 ni.com

17 Niscope Averager Fetch Binary Average Purpose This function fetches unscaled, uncalibrated data from the onboard memory of the device. The function works similarly to other NI-SCOPE functions. This function does not support fetching relative to any other location than pretrigger. The function begins fetching the averaged data after the acquisition is complete. Returned data will be 24-bit left-justified signed binary data in a 32-bit integer container. Data allocation in C is different for this function compared to standard NI-SCOPE function calls. The allocation code is as follows: niscope_actualrecordlength (vi, &actualrecordlength) waveformptr = malloc (sizeof (ViReal64)* actualrecordlength); The Niscope Averager fetch functions cannot take more than one channel per fetch call. To fetch multiple channels you must call the function multiple times, using one channel name per call. Function Prototypes C Function ViStatus niscopeavg_fetchavgbinary32 (ViSession vi, ViConstString channel, ViReal64 timeout, ViInt32 numpts, ViInt32* actualnumberofrecordsaccumulated, ViInt32* wfm, struct niscope_wfminfo* wfminfo); LabVIEW VI National Instruments Corporation 17 NI PCI-5153EX User Guide

18 Parameters Name vi channel timeout numpts wfm wfminfo Description The instrument handle you obtain from niscope_init that identifies a particular instrument session. The channel from which to acquire data. The amount of time, in seconds, the function should wait for the data before returning an error. The number of points to fetch from the device. The waveform data. The waveform information, including calibration constants and timestamps. National Instruments, NI, ni.com, and LabVIEW are trademarks of National Instruments Corporation. Refer to the Terms of Use section on ni.com/legal for more information about National Instruments trademarks. Other product and company names mentioned herein are trademarks or trade names of their respective companies. For patents covering National Instruments products/technology, refer to the appropriate location: Help»Patents in your software, the patents.txt file on your media, or the National Instruments Patent Notice at ni.com/patents National Instruments Corporation. All rights reserved A-01 Oct09