Function pointers in Python errors about extra arguments given

小能豆

Function pointers in Python errors about extra arguments given

I am trying to write a streaming example for Picoscope 5000 series into a object oriented script. The example is available on their repo found here: PicoScope Streaming example. Here is an extract of the related code that I adapted from the example

class Readpicochannel():
    """Class for setting up and reading picoscope streams"""

    def streaming_init(self):
        self.status["runStreaming"] = ps.ps5000aRunStreaming(self.chandle, ctypes.byref(sampleInterval), sampleUnits, self.streaming_vars["maxPreTriggerSamples"], totalSamples, self.streaming_vars["autoStopOn"], self.streaming_vars["downsampleRatio"], ps.PS5000A_RATIO_MODE['PS5000A_RATIO_MODE_NONE'], sizeOfOneBuffer)
        assert_pico_ok(self.status["runStreaming"])
        print(f"Capturing at sample interval {actualSampleIntervalNs}ns")


    def streaming_callback(self, handle, noOfSamples, startIndex, overflow, triggerAt, triggered, autoStop, param):
        self.buffer_var["wasCalledBack"] = True
        destEnd = self.buffer_var["nextSample"] + noOfSamples
        sourceEnd = startIndex + noOfSamples
        complete_buffer[self.buffer_var["nextSample"]:destEnd] = self.max_capture_buffer[startIndex:sourceEnd]
        self.buffer_var["nextSample"] += self.noOfSamples
        if autoStop:
            self.buffer_var["autoStopOuter"] = True


    def cont_streaming(self, cFuncPtr, tester):
        if tester:
            print("Entered testing loop")
            while self.buffer_var["nextSample"] < totalSamples and not self.buffer_var["autoStopOuter"]:       
                self.buffer_var["wasCalledBack"] = False
                self.status["getStreamingLastestValues"] = ps.ps5000aGetStreamingLatestValues(self.chandle, cFuncPtr, None)
                if not self.buffer_var["wasCalledBack"]:
                    time.sleep(0.01) 
            print("Done capturing values")
            return self.convert_d2a()
        else:
            while True:
                wasCalledBack = False
                self.status["getStreamingLastestValues"] = ps.ps5000aGetStreamingLatestValues(self.chandle, cFuncPtr, None)
                if not wasCalledBack:
                    time.sleep(0.01)
                    return self.convert_d2a()

Edit: after reading the comments and adding the rest of the args, I get this error now:

    AttributeError: 'Readpicochannel' object has no attribute 'noOfSamples'

Not sure what is wrong with my approach or if I didnt configure the C pointer to the function properly. Any help is appreciated. Thanks

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2023-12-23

共1个答案

小能豆

It seems that there are some issues with how you’re using the noOfSamples variable in your code. Specifically, it appears that noOfSamples is not defined within the scope of the cont_streaming method.

You should make sure that noOfSamples is defined as an attribute of your class, or it should be passed as an argument to the cont_streaming method. Additionally, you need to replace instances of self.noOfSamples with the correct variable name.

Here’s a modified version of your code that defines noOfSamples as an attribute of the class and passes it as an argument to the cont_streaming method:

class Readpicochannel():
    """Class for setting up and reading picoscope streams"""

    def __init__(self):
        self.noOfSamples = 0  # Initialize noOfSamples as an attribute

    def streaming_init(self):
        # ... (your existing code)

    def streaming_callback(self, handle, noOfSamples, startIndex, overflow, triggerAt, triggered, autoStop, param):
        self.buffer_var["wasCalledBack"] = True
        destEnd = self.buffer_var["nextSample"] + noOfSamples
        sourceEnd = startIndex + noOfSamples
        complete_buffer[self.buffer_var["nextSample"]:destEnd] = self.max_capture_buffer[startIndex:sourceEnd]
        self.buffer_var["nextSample"] += self.noOfSamples  # Use self.noOfSamples here
        if autoStop:
            self.buffer_var["autoStopOuter"] = True

    def cont_streaming(self, cFuncPtr, tester):
        if tester:
            print("Entered testing loop")
            while self.buffer_var["nextSample"] < totalSamples and not self.buffer_var["autoStopOuter"]:
                self.buffer_var["wasCalledBack"] = False
                self.status["getStreamingLastestValues"] = ps.ps5000aGetStreamingLatestValues(self.chandle, cFuncPtr, None)
                if not self.buffer_var["wasCalledBack"]:
                    time.sleep(0.01)
            print("Done capturing values")
            return self.convert_d2a()
        else:
            while True:
                wasCalledBack = False
                self.status["getStreamingLastestValues"] = ps.ps5000aGetStreamingLatestValues(self.chandle, cFuncPtr, None)
                if not wasCalledBack:
                    time.sleep(0.01)
                    return self.convert_d2a()

Make sure to adjust the rest of your code accordingly. If noOfSamples needs to be initialized or modified somewhere else, you should do that in your code.

2023-12-23