Python中PicoScope 2000系列示波器无法捕获Arduino输出方波信号问题排查

我正尝试用Python捕获Arduino输出的简单方波信号（10ms高电平、10ms低电平），信号接在PicoScope 2000系列的B通道，但完全看不到信号。我已经反复检查了设置，看起来都没问题。

我的代码如下：

from ctypes import CFUNCTYPE, POINTER, c_int16, c_uint32, c_byte
import matplotlib.pyplot as plt
import numpy as np
from picosdk.ps2000 import ps2000
from picosdk.functions import assert_pico2000_ok
from picosdk.functions import adc2mV

from picosdk.ctypes_wrapper import C_CALLBACK_FUNCTION_FACTORY
import time
from picosdk.PicoDeviceEnums import picoEnum
import serial

# Set up callback for streaming mode
CALLBACK = C_CALLBACK_FUNCTION_FACTORY(
    None,
    POINTER(POINTER(c_int16)),
    c_int16,
    c_uint32,
    c_int16,
    c_int16,
    c_uint32
)

# List to hold ADC values
adc_values = []

# Callback function to handle data
def get_overview_buffers(buffers, _overflow, _triggered_at, _triggered, _auto_stop, n_values):
    adc_values.extend(buffers[0][0:n_values])

callback = CALLBACK(get_overview_buffers)


# Open a PicoScope 2000 Series device and start data collection
with ps2000.open_unit() as device:
    print('Device Info: {}'.format(device.info))

    # Set up channel A
    res = ps2000.ps2000_set_channel(
        device.handle,
        picoEnum.PICO_CHANNEL['PICO_CHANNEL_B'],
        True,
        picoEnum.PICO_COUPLING['PICO_DC'],
        ps2000.PS2000_VOLTAGE_RANGE['PS2000_10V'],
    )
    assert_pico2000_ok(res)
    print("Channel A set up successfully.")

    # Initialize fast streaming mode
    res = ps2000.ps2000_run_streaming_ns(
        device.handle,
        500,  # Sampling interval in nanoseconds
        2,    # Sampling time unit (2 = nanoseconds)
        500_000,  # Maximum samples to collect
        False,  # Do not stop automatically when maximum samples are reached
        1,    # Number of samples to aggregate together
        500_000  # Maximum samples to store before overwriting
    )
    assert_pico2000_ok(res)
    print("Streaming mode initialized.")

    # Start data collection in streaming mode
    print("Starting data collection...")
    start_time = time.time()
    while time.time() - start_time < 1.0:  # Collect for 1 seconds
        ps2000.ps2000_get_streaming_last_values(device.handle, callback)


    # Stop the PicoScope
    ps2000.ps2000_stop(device.handle)
    print("PicoScope stopped successfully.")

    mv_values_B = adc2mV(adc_values, ps2000.PS2000_VOLTAGE_RANGE['PS2000_10V'],c_int16(32767))

    # Generate time axis
    sampling_interval = 500e-9  # Sampling interval in seconds (500 ns)
    time_axis = np.arange(len(mv_values_B)) * sampling_interval * 1e3  # Convert to milliseconds

    # Plot the data
    fig, ax = plt.subplots()
    ax.set_xlabel("Time (ms)")
    ax.set_ylabel("Voltage (mV)")
    ax.plot(time_axis, mv_values_B, label="Channel B Voltage")
    ax.grid(True)
    ax.legend()
    plt.title("Channel B Data Over Time")
    plt.show()

代码运行后生成的图如下：

但我用Pico官方软件查看B通道时，能正常看到波形：

到底哪里出问题了？我已经尝试过不同的选项，比如切换到块读取模式、延长录制时间等。我是参考Pico的官方文档来写的代码。

备注：内容来源于stack exchange，提问作者gjossep