[Try to use SPI function in digital discovery in Linux. Undefined symbol]

The error is the following

File "/usr/lib64/python3.7/ctypes/__init__.py", line 369, in __getattr__
    func = self.__getitem__(name)
  File "/usr/lib64/python3.7/ctypes/__init__.py", line 374, in __getitem__
    func = self._FuncPtr((name_or_ordinal, self))
AttributeError: /usr/lib/libdwf.so: undefined symbol: FDwfDigitalSpiSelectSet
pure virtual method called
terminate called without an active exception
Aborted
 

I tried to use SPI built in function for digital discovery. FDwfDigitalSpiSelectSet and other spi functions are what I try to use.

My code works in Windows environment, but in Linux system, I got this error. Actually, I have some codes running (mostly IO stuff) on Linux system, but this code involving SPI built-in function is not working. The libdwf.so may have some problems. Could you please help me to solve this problem? Thanks.

 

Best regards, Minghan Chao

[Digital Discovery pattern generator, finite sequence output]

I am trying to generate digital sequence of outputs, with four channels (using Digital Discovery). I want them to be synchonized.

My problem is I only want the pattern output to be finite sequence (not looping). I used the example DigitalOut_Custom.py to do the job. But the sequence always restart. Could you please tell me the right way to generate a finite sequence of 0 and 1s? Is using the custom output function the right way? Thanks.

I have attached the code. Currently it uses only two channels.

"""
   DWF Python Example
   Author:  Digilent, Inc.
   Revision:  2019-09-02

   Requires:
       Python 2.7, 3
   Description:
   Generates a custom pattern
"""

from ctypes import *
from WF_SDK.dwfconstants import *
import sys
import time

if sys.platform.startswith("win"):
    dwf = cdll.dwf
elif sys.platform.startswith("darwin"):
    dwf = cdll.LoadLibrary("/Library/Frameworks/dwf.framework/dwf")
else:
    dwf = cdll.LoadLibrary("libdwf.so")

hdwf = c_int()

version = create_string_buffer(16)
dwf.FDwfGetVersion(version)
print("DWF Version: "+str(version.value))

print("Opening first device")
dwf.FDwfDeviceOpen(c_int(-1), byref(hdwf))

if hdwf.value == 0:
    print("failed to open device")
    szerr = create_string_buffer(512)
    dwf.FDwfGetLastErrorMsg(szerr)
    print(str(szerr.value))
    quit()

print("Configuring Digital Out")

hzSys = c_double()
dwf.FDwfDigitalOutInternalClockInfo(hdwf, byref(hzSys))

print(hzSys)

hzRate = 10e3

data_py_clk=[0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0]
data_py_din=[0,0,0,1,1,1,0,0,0,1,1,1,0,0,0,1,1,1,0,0,0,1,1]

# how many bytes we need to fit this many bits, (+7)/8
rgbdata=(c_ubyte*((len(data_py_clk)+7)>>3))(0)

# array to bits in byte array
for i in range(len(data_py_clk)):
    if data_py_clk[i] != 0:
        rgbdata[i>>3] |= 1<<(i&7)

#clk pin session
clk_pin=0
# generate pattern
dwf.FDwfDigitalOutEnableSet(hdwf, c_int(clk_pin), c_int(1))
dwf.FDwfDigitalOutTypeSet(hdwf, c_int(clk_pin), DwfDigitalOutTypeCustom)

# 10kHz sample rate
dwf.FDwfDigitalOutDividerSet(hdwf, c_int(clk_pin), c_int(int(hzSys.value/hzRate))) # set sample rate
dwf.FDwfDigitalOutDataSet(hdwf, c_int(clk_pin), byref(rgbdata), c_int(len(data_py_clk)))

rgbdata_din=(c_ubyte*((len(data_py_din)+7)>>3))(0)

# array to bits in byte array
for i in range(len(data_py_din)):
    if data_py_din[i] != 0:
        rgbdata_din[i>>3] |= 1<<(i&7)

#din pin session
din_pin=1
# generate pattern
dwf.FDwfDigitalOutEnableSet(hdwf, c_int(din_pin), c_int(1))

# 10kHz sample rate
dwf.FDwfDigitalOutDividerSet(hdwf, c_int(din_pin), c_int(int(hzSys.value/hzRate))) # set sample rate
dwf.FDwfDigitalOutDataSet(hdwf, c_int(din_pin), byref(rgbdata_din), c_int(len(data_py_din)))

print("Generating pattern...")

dwf.FDwfDigitalOutConfigure(hdwf, c_int(1))

dwf.FDwfDigitalOutReset(hdwf)
dwf.FDwfDeviceCloseAll()