waveforms sdk Using ScanShift Acquisition Mode in WaveForms SDK

[tj38]

Hi, I am trying to figure out how to use either ScanShift or ScanScreen acquisition mode for Digital Inputs into the Analog Discovery. And well, I can't get it to work, and haven't really been able to find any information online. My overall goal is to be able to stream out the digital data, so that I can capture and store more (continuous) data than the 16 kB buffer size. This doesn't have to run fast, I need to capture at 10,000 samples per second.

The problem seems to be that the Digital In is staying in a "trigger" state. I am using Python, and using the function:

dwf.FDwfDigitalInStatus(hdwf, c_int(1), byref(sts))

always sets sts to c_int(3), which according to dwfconstants.py file (included in python samples folder with the SDK), this corresponds to stsTrig.

 

Here is one version of the code I have been playing with, it is modified from the DigitalIn_Acquisition.py sample program (note I can switch to C, if that would be easier, I am not actually very familar with Python):
 

    """
       DWF Python Example 5
       Author:  Digilent, Inc.
       Revision: 10/17/2013
    
       Requires:                       
           Python 2.7, numpy, matplotlib
           python-dateutil, pyparsing
    """
    from ctypes import *
    from dwfconstants import *
    import math
    import time
    #import matplotlib.pyplot as plt
    import sys
    
    #declare ctype variables
    if sys.platform.startswith("win"):
        dwf = cdll.dwf
    else:
        dwf = cdll.LoadLibrary("libdwf.so")
    
    hdwf = c_int()
    sts = c_byte()
    
    #print DWF version
    version = create_string_buffer(16)
    dwf.FDwfGetVersion(version)
    print "DWF Version: "+version.value
    
    #open device
    print "Opening first device"
    dwf.FDwfDeviceOpen(c_int(-1), byref(hdwf))
    
    if hdwf.value == hdwfNone.value:
        print "failed to open device"
        quit()
    
    ofile = open("DigInTestData.txt", 'w') #open file in write mode
    print "File opened to write."
    ofile.truncate() # delete existing content
    
    print "Preparing to read sample..."
    
        
    # generate counter (Connecting these pins back to the inputs to test)
    for i in range(12, 16):
        dwf.FDwfDigitalOutEnableSet(hdwf, c_int(i), c_int(1)) #(dRef, chan, Enable(1)orDisable(0))
        dwf.FDwfDigitalOutDividerSet(hdwf, c_int(i), c_int(33332*(1<<(i-12)))) #(dRef, chan, clock_divider)
        dwf.FDwfDigitalOutCounterSet(hdwf, c_int(i), c_int(1), c_int(1)) #(dRef,chan,clkcycs_low,clkcycs_high)
    
    dwf.FDwfDigitalOutConfigure(hdwf, c_int(1)) #(dRef, Enable(1)orDisable(0))
    
    
    #ScanShift Mode
    dwf.FDwfDigitalInAcquisitionModeSet(hdwf, acqmodeScanShift) #TH:(dRef, acqmode)
    
    #sample rate = system frequency / divider, 100MHz/1
    dwf.FDwfDigitalInDividerSet(hdwf, c_int(10000)) #TH: 1->10,000 #(dRef, clk_divider)
    # 16bit per sample format
    dwf.FDwfDigitalInSampleFormatSet(hdwf, c_int(8)) #(dRef, Format(8,16,or32))
    # set number of sample to acquire
    cSamples = 1
    rgwSamples = (c_uint8*cSamples)() #rgwSamples is a ?pointer? to a ctype array acting as a "buffer"
    dwf.FDwfDigitalInBufferSizeSet(hdwf, c_int(cSamples)) #(dRef,BufSize) duh...
    
    rgpy=[]
    
    #dwf.FDwfDigitalInTriggerAutoTimeoutSet(hdwf, c_double(0.2097152))
    dwf.FDwfDigitalInConfigure(hdwf, c_bool(0), c_bool(1)) #(dRef,reconfig?,StartRec)
    while True:
        dwf.FDwfDigitalInStatus(hdwf, c_int(1), byref(sts)) #(dRef,ReadData(TorF), status_variable)
        print "STS VAL: " + str(sts.value)
        if (sts.value == stsTrig.value):
 #only changed to stsTrig so that it will escape this loop
            break
        time.sleep(1)
    print "   waiting to finish"
    time.sleep(1)
    
    # begin acquisition
    for I in range(0,100):
        # get samples, byte size
        dwf.FDwfDigitalInStatusData(hdwf, rgwSamples, cSamples) #(dRf,point->databuffer,numOfDataBytes2Copy)
        rgpy.append(rgwSamples[0])
    
    dwf.FDwfDeviceCloseAll()
    for num in rgpy:
        ofile.write(str(num)+'\n')
        
    for i in range(0,15):
        print(str(rgpy))
    ##
    ##print()
    ##print(str(rgpy[0]))
    
    
    print "...written to."
    ofile.close()
    print "and closed."

 

This just results in one value be stored in all 100 spots. An example of a shell output:
 

    DWF Version: 2.7.5
    Opening first device
    File opened to write.
    Preparing to read sample...
    STS VAL: 3
       waiting to finish
    8
    8
    8
    8
    8
    8
    8
    8
    8
    8
    8
    8
    8
    8
    8
    ...written to.
    and closed.

 

Any help/advice anyone can give me would be greatly appreciated; I am really new to all of this.

 

[attila]

Hello,

I sent you the newer software/SDK version in private message.
You will find in this the DigitalIn_Record.py example, which generates a counter and records a large number of samples in text file.

[tj38]

Thank you attila, it was exactly what I needed!

[muelmat]

Hello,

I sent you the newer software/SDK version in private message.
You will find in this the DigitalIn_Record.py example, which generates a counter and records a large number of samples in text file.

Hi Attila

Could you also send me the newer Version of the SDK? I searched everywhere on your homepage and I didn't find any SDK with the DigitalIn_Record.py file in it. The newest SDK I found on your homepage is the Waveform 2.7.5.

Any help would be greatly appreciated

Thank you in advanve

Matthias

[attila]

Hello,

I sent the download links to the email of your forum account.

 

[muelmat]

Hi Attila

Thank you very much for the new SDK!

Greetings

Matthias

[SweetwaterPirate]

Can I have it too? I'm using LabView to do the data acquisition. I can use the code as an example. 

[attila]

You can find the latest version at:
https://reference.digilentinc.com/waveforms3

[SweetwaterPirate]

How did you manage to get out of the triggered state?

[attila]

In the script 100k samples are recorded at 10kHz, so it takes 10(+2) seconds to finish.

This is just an example, you can modify it for your needs.

[jeremy.006]

Is there a way to set up this script so that it just samples forever (like in Waveforms)? I've looked in the documentation and haven't found anything.

[jeremy.006]

Looks like if you set the second parameter of the FDwfAnalogInRecordLengthSet call to -1, it will go for a long time. Is this the right way to do it?

[attila]

Yes. For undetermined length of acquisition you can use record with length 0 (or -1).
You can also use the scanshift acquisition mode to get in each iteration the last buffer size of samples.