Incorrect data in from DigitalIn using pysdk

[AjayLeafi]

Hi everyone,

Objective of the code: After confirming that the data is ready, the code reads the data from the specified channels. The goal is to identify changes in the signal, particularly detecting when there is a transition or edge change in the input.

Setup: The code configures a system to read digital inputs from two channels, DIO5 and DIO6.

Trigger Setup: It sets up a trigger mechanism, likely to start the data acquisition process when a specific condition (trigger) is met on the digital input.

Data Ready Check: It checks if the data is ready to be read. This is crucial to ensure that the system is prepared to provide meaningful information.

 

def counter(device_data, channel1,channel2, timout,counts,rpm):
    """
    Count the edge transitions on 2 channels

    parameters: - device data
                - selected DIO channel number
                - selected DIO channel number
                - duration of counter
                - return value of counts
                - calculated rpm value
    """

    sts = ctypes.c_byte()


    hzDI = ctypes.c_double()

    cSamples = 4096
    rgwSamples = (ctypes.c_uint16*cSamples)()
  
    current_time = datetime.now()

    # Print the current time
    print("Current System Time:", current_time)
    print("Waiting for acquisition...")
    while True:
        dwf.FDwfDigitalInStatus(device_data.handle, ctypes.c_int(1), ctypes.byref(sts))
        print(sts.value)
        if sts.value != None :
            break
        time.sleep(1)
    print("   done")

    # Get the current system time
    current_time = datetime.now()

    # Print the current time
    print("Current System Time:", current_time)                                                                 

    # get samples, byte size
    dwf.FDwfDigitalInStatusData(device_data.handle, rgwSamples, 2*cSamples)
    dwf.FDwfDeviceCloseAll()
    print(rgwSamples)

    # Extract dio1 (f1) and dio2 (f2) values
    dioa = [(sample >> channel1-1) for sample in rgwSamples]
    diob = [(sample >> channel2-1) for sample in rgwSamples]

    count = 0
    edge_indices_dio1, edge_samples_dio1 = find_edges_with_indices(dioa)
    edge_indices_dio2, edge_samples_dio2 = find_edges_with_indices(diob)
    for idx, sample in zip(edge_indices_dio1, edge_samples_dio1):
        print(f"DIO1 Edge at Sample {idx}, Value: {sample}")
        count = count +1
    for idx, sample in zip(edge_indices_dio2, edge_samples_dio2):
        print(f"DIO2 Edge at Sample {idx}, Value: {sample}")

    speeds_dio1 = calculate_speed(edge_indices_dio1, edge_samples_dio1, hzDI.value/100e6)
    speeds_dio2 = calculate_speed(edge_indices_dio2, edge_samples_dio2, hzDI.value/100e6)

    for i, speed in enumerate(speeds_dio1, start=1):
        print(f"DIO1 Speed between Edges {i} and {i+1}: {speed:.2f} units per second")

    for i, speed in enumerate(speeds_dio2, start=1):
        print(f"DIO2 Speed between Edges {i} and {i+1}: {speed:.2f} units per second")

    # time.sleep(100)

def find_edges_with_indices(dio):
    edge_indices = []  # List to store the indices of detected edges
    edge_samples = []  # List to store the sample values at edge transitions
    
    prev_sample = dio[0]  # Initialize with the first sample
    
    for i, sample in enumerate(dio[1:], start=1):
        if sample != prev_sample:
            edge_indices.append(i)
            edge_samples.append(sample)
        prev_sample = sample
    
    return edge_indices, edge_samples

def input_trigger_set(device_data,channel1,channel2):
    print("input_trigger set")
    set_mode(device_data=device_data,channel=channel1,output=True)
    # pull_direction = pull()
    # set_pull(device_data=device_data,channel=channel1, direction=pull_direction.idle)
    set_mode(device_data=device_data,channel=channel2,output=True)
    # set_pull(device_data=device_data,channel=channel2, direction=pull_direction.idle)

    sts = ctypes.c_byte()
    hzDI = ctypes.c_double()
    dwf.FDwfDigitalInInternalClockInfo(device_data.handle, ctypes.byref(hzDI))
    dwf.FDwfDigitalInDividerSet(device_data.handle, ctypes.c_int(int(hzDI.value/100e6))) # 100MHz

    # sample rate = system frequency / divider
    hzDI = ctypes.c_double()
    dwf.FDwfDigitalInInternalClockInfo(device_data.handle, ctypes.byref(hzDI))
    dwf.FDwfDigitalInDividerSet(device_data.handle, ctypes.c_int(int(hzDI.value/100e6))) # 100MHz
    # 16bit per sample format
    dwf.FDwfDigitalInSampleFormatSet(device_data.handle, ctypes.c_int(16))
    # set number of sample to acquire
    cSamples = 4096
    rgwSamples = (ctypes.c_uint16*cSamples)()
    dwf.FDwfDigitalInBufferSizeSet(device_data.handle, ctypes.c_int(cSamples))

    # Set trigger
    dwf.FDwfDigitalInTriggerSourceSet(device_data.handle,ctypes.c_int(3))
    dwf.FDwfDigitalInTriggerPositionSet(device_data.handle, ctypes.c_int(int(cSamples/10-1)))
    dwf.FDwfDigitalInTriggerSet(device_data.handle, ctypes.c_int(0), ctypes.c_int(0), ctypes.c_int(1<<channel1), ctypes.c_int(1<<channel1)) 

    # begin acquisition
    dwf.FDwfDigitalInConfigure(device_data.handle, ctypes.c_int(1), ctypes.c_int(1))

The data i get out 

dioa: [21, 29, 2926, 29, 21, 29, 2926, 29, 21, 29, 2926, 29, 21, 29, ...]

diob [10, 12, 1463, 12, 10, 12, 1463, 12, 10, 12, 1463, 12, 10, 12, ...]

 

what could be the problem?

 

 

Edited November 30, 2023 by AjayLeafi
formatting