tests: validate last sample hold

- After a non-cyclic buffer is pushed, the last sample will idle
at the output untill a new sample is pushed or the channel is stopped.
- When the oposite channel idles at 0V we test for an interval of +/- 0.2V
because a small spikes appears ocasionally if the swing on the channel that is being
pushed is to large.

Signed-off-by: Adrian Stanea <[email protected]>

tests/analog_functions.py

@@ -13,10 +13,12 @@
 import random
 import sys
 import reset_def_values as reset
-from helpers import get_result_files, save_data_to_csv, plot_to_file
+from helpers import get_result_files, get_sample_rate_display_format, get_time_format, save_data_to_csv, plot_to_file
 from open_context import ctx_timeout, ctx
 from create_files import results_file, results_dir, csv
 
+from shapefile import shape_gen, Shape
+
 # dicts that will be saved to csv files
 shape_csv_vals = {}
 ampl_csv_vals = {}
@@ -1265,4 +1267,248 @@ def test_buffer_transition_glitch(channel, ain, aout, trig, waveform, amplitude=
                      f'buffer_glitch_plot_ch{channel}_{waveform}.png',
                      data_marked=filtered_peaks)
 
-    return num_peaks
+    return num_peaks
+
+
+def get_experiment_config_for_sample_hold(dac_sr):
+    cfg = {}
+    if dac_sr == 75_000_000:
+        cfg["dac_sr"] = dac_sr
+        cfg["adc_sr"] = 100_000_000
+        cfg["buffer_size"] = 20_000
+        cfg["trig_threshold"] = 2.9
+        cfg["amplitude"] = 5
+        cfg["samples_per_period"] = 1024 * 8
+        cfg["offset"] = 0
+    elif dac_sr == 7_500_000:
+        cfg["dac_sr"] = dac_sr
+        cfg["adc_sr"] = 100_000_000
+        cfg["buffer_size"] = 30_000
+        cfg["trig_threshold"] = 2.9
+        cfg["amplitude"] = 5
+        cfg["samples_per_period"] = 1024
+        cfg["offset"] = 0
+    elif dac_sr == 750_000:
+        cfg["dac_sr"] = dac_sr
+        cfg["adc_sr"] = 10_000_000
+        cfg["buffer_size"] = 30_000
+        cfg["trig_threshold"] = 2.9
+        cfg["amplitude"] = 5
+        cfg["samples_per_period"] = 1024
+        cfg["offset"] = 0
+    elif dac_sr == 75_000:
+        cfg["dac_sr"] = dac_sr
+        cfg["adc_sr"] = 1_000_000
+        cfg["buffer_size"] = 30_000
+        cfg["trig_threshold"] = 2.9
+        cfg["amplitude"] = 5
+        cfg["samples_per_period"] = 1024
+        cfg["offset"] = 0
+    elif dac_sr == 7_500:
+        cfg["dac_sr"] = dac_sr
+        cfg["adc_sr"] = 1_000_000
+        cfg["buffer_size"] = 30_000
+        cfg["trig_threshold"] = 2.9
+        cfg["amplitude"] = 5
+        cfg["samples_per_period"] = 128
+        cfg["offset"] = 0
+    # 750 Hz ommited to avoid long test duration
+    else:
+        raise ValueError("Invalid DAC sample rate.")
+    return cfg
+
+def are_values_within_range(data: np.ndarray, lower_bound, upper_bound, chn):
+    assert lower_bound < upper_bound, "Invalid bounds"
+    is_CH0_in_range = np.all((lower_bound <= data[0]) & (data[0] <= upper_bound))
+    is_CH1_in_range = np.all((lower_bound <= data[1]) & (data[1] <= upper_bound))
+    if chn is None:
+        return is_CH0_in_range and is_CH1_in_range
+    elif chn == libm2k.ANALOG_IN_CHANNEL_1:
+        return is_CH0_in_range
+    elif chn == libm2k.ANALOG_IN_CHANNEL_2:
+        return is_CH1_in_range
+    else:
+        raise ValueError(f"Unknown channel: {chn}")
+
+def test_last_sample_hold(
+    ain: libm2k.M2kAnalogIn,
+    aout: libm2k.M2kAnalogOut,
+    trig: libm2k.M2kHardwareTrigger,
+    ctx: libm2k.M2k,
+    cfg, channel
+):
+    def step_ramp_rising(aout_chn, trig_chn, buffer_ramp_up):
+        set_trig(trig, trig_chn, 8192, libm2k.RISING_EDGE_ANALOG, -cfg.get("trig_threshold"))
+        ain.startAcquisition(cfg.get("buffer_size"))
+        if aout_chn is None:
+            aout.push([buffer_ramp_up, buffer_ramp_up])
+        else:
+            aout.push(aout_chn, buffer_ramp_up)
+        data = np.array(ain.getSamples(cfg.get("buffer_size")))
+        # Flush values from previous buffer
+        ain.stopAcquisition()
+        return data
+
+    def step_ramp_falling(aout_chn, trig_chn, buffer_ramp_down):
+        set_trig(trig, trig_chn, 8192, libm2k.FALLING_EDGE_ANALOG, cfg.get("trig_threshold"))
+        ain.startAcquisition(cfg.get("buffer_size"))
+        if aout_chn is None:
+            aout.push([buffer_ramp_down, buffer_ramp_down])
+        else:
+            aout.push(aout_chn, buffer_ramp_down)
+        data = np.array(ain.getSamples(cfg.get("buffer_size")))
+        # Flush values from previous buffer
+        ain.stopAcquisition()
+        return data
+
+    def check_for_glitch(data, threshold=0.3):
+        # The glitch is unwanted and happened in between the last sample of the previous buffer and the first sample of the new buffer.
+        # NOTE: At DAC_SR <= 7.5 KHz we see oscilations due to the response of the HDL filter
+        glitch_found = False
+        for  chn_samples in data:
+            if any(abs(left - right) >= threshold for left, right in zip(chn_samples, chn_samples[1:])):
+                glitch_found = True
+        return glitch_found   
+
+    file_name, dir_name, csv_path = get_result_files(gen_reports)
+    test_name = "sample_hold"
+    data_string = []
+
+    chn_str = "both_channels" if channel is None else f"CH{channel}"
+    sr_str = get_sample_rate_display_format(cfg.get("dac_sr"))
+    x_time, x_label = get_time_format(cfg.get("buffer_size"), cfg.get("adc_sr"))
+
+    if gen_reports:
+        subdir_name = f"{dir_name}/last_sample_hold/{chn_str}"
+        os.makedirs(subdir_name, exist_ok=True)
+
+    SLEEP = 0.15 
+    glitched = False
+    is_last_sample_hold_ok = True # Assume it is ok until proven otherwise
+    is_idle_ok = True
+    assert channel in [libm2k.ANALOG_IN_CHANNEL_1, libm2k.ANALOG_IN_CHANNEL_2, None], "Invalid channel ... None means use both channels"
+    trig_chn = libm2k.ANALOG_IN_CHANNEL_1 if channel is None else channel
+
+    buffer_ramp_up = shape_gen(n=cfg["samples_per_period"],
+                                amplitude=cfg["amplitude"],
+                                offset=cfg["offset"])[Shape.RISING_RAMP.value]
+    buffer_ramp_down = shape_gen(n=cfg["samples_per_period"],
+                                amplitude=cfg["amplitude"],
+                                offset=cfg["offset"])[Shape.FALLING_RAMP.value]
+
+    ain.enableChannel(libm2k.ANALOG_IN_CHANNEL_1, True)
+    ain.enableChannel(libm2k.ANALOG_IN_CHANNEL_2, True)
+    ain.setSampleRate(cfg.get("adc_sr"))
+    ain.setRange(0, libm2k.PLUS_MINUS_25V)
+    ain.setRange(1, libm2k.PLUS_MINUS_25V)
+
+    aout.setSampleRate(0, cfg.get("dac_sr"))
+    aout.setSampleRate(1, cfg.get("dac_sr"))
+    aout.setKernelBuffersCount(0, 4)
+    aout.setKernelBuffersCount(1, 4)
+    aout.enableChannel(0, True)
+    aout.enableChannel(1, True)
+    aout.setCyclic(False)
+
+    # Alternate between rising and falling ramps: rising, falling, rising, falling
+    # NOTE: we selected an arbitraty number of samples from both ends to validate sample hold and reset functionality
+    # 1: Rising
+    data = step_ramp_rising(channel, trig_chn, buffer_ramp_up)
+    if channel is None: 
+        # Both channels should idle at 0V before push due to being reset
+        is_idle_ok = is_idle_ok and are_values_within_range(data[:, :2000], -0.20, 0.20, channel)
+        assert is_idle_ok, "STEP1: Both channels should idle low before push due to being reset"
+    elif channel == libm2k.ANALOG_IN_CHANNEL_1:
+        # CH2 should idle at 0V if we are testing CH1
+        is_idle_ok = is_idle_ok and are_values_within_range(data, -0.20, 0.20, libm2k.ANALOG_IN_CHANNEL_2)
+        assert is_idle_ok, "STEP1: CH2 should idle at 0V if we are testing CH1"
+    elif channel == libm2k.ANALOG_IN_CHANNEL_2:
+        is_idle_ok = is_idle_ok and are_values_within_range(data, -0.20, 0.20, libm2k.ANALOG_IN_CHANNEL_1)
+        assert is_idle_ok, "STEP1: CH1 should idle at 0V if we are testing CH2"
+    # Shoud hold last sample from new buffer for current channel config
+    is_idle_ok = is_idle_ok and are_values_within_range(data[:, -2000:], cfg["amplitude"] * 0.85, cfg["amplitude"] * 1.15, channel)
+
+    if gen_reports:
+        plot_to_file(title=f"Last Sample Hold: {chn_str} - {sr_str} - Rising Ramp",
+                    data=data[0],
+                    data1=data[1],
+                    x_data=x_time,
+                    xlabel = x_label, 
+                    dir_name=subdir_name,
+                    y_lim=(-6, 6),
+                    filename=f"last_sample_hold_{chn_str}_{sr_str}_step1.png")
+    time.sleep(SLEEP)  # wait for the DAC output to settle with last sample
+    # 2: Falling
+    data = step_ramp_falling(channel, trig_chn, buffer_ramp_down)
+    # Shoud start with last sample from previous buffer
+    is_last_sample_hold_ok = is_last_sample_hold_ok and are_values_within_range(data[:, :2000], cfg["amplitude"] * 0.85, cfg["amplitude"] * 1.15, channel)
+    # Shoud hold last sample from new buffer
+    is_last_sample_hold_ok = is_last_sample_hold_ok and are_values_within_range(data[:, -2000:], -cfg["amplitude"] * 1.15, -cfg["amplitude"] * 0.85, channel)
+    if channel == libm2k.ANALOG_IN_CHANNEL_1:
+        # CH2 should idle at 0V if we are testing CH1
+        is_idle_ok = is_idle_ok and are_values_within_range(data, -0.20, 0.20, libm2k.ANALOG_IN_CHANNEL_2)
+        assert is_idle_ok, "STEP2: CH2 should idle at 0V if we are testing CH1"
+    elif channel == libm2k.ANALOG_IN_CHANNEL_2:
+        is_idle_ok = is_idle_ok and are_values_within_range(data, -0.20, 0.20, libm2k.ANALOG_IN_CHANNEL_1)
+        assert is_idle_ok, "STEP2: CH1 should idle at 0V if we are testing CH2"
+    glitched = glitched or check_for_glitch(data)
+    if gen_reports:
+        plot_to_file(title=f"Last Sample Hold: {chn_str} - {sr_str} - Falling Ramp",
+                    data=data[0],
+                    data1=data[1],
+                    x_data=x_time,
+                    xlabel = x_label, 
+                    dir_name=subdir_name,
+                    y_lim=(-6, 6),
+                    filename=f"last_sample_hold_{chn_str}_{sr_str}_step2.png")
+    time.sleep(SLEEP)  # wait for the DAC output to settle with last sample
+    # 3: Rising
+    data = step_ramp_rising(channel, trig_chn, buffer_ramp_up)
+    # Shoud start with last sample from previous buffer
+    is_last_sample_hold_ok = is_last_sample_hold_ok and are_values_within_range(data[:, :2000], -cfg["amplitude"] * 1.15, -cfg["amplitude"] * 0.85, channel)
+    # Shoud hold last sample from new buffer
+    is_last_sample_hold_ok = is_last_sample_hold_ok and are_values_within_range(data[:, -2000:], cfg["amplitude"] * 0.85, cfg["amplitude"] * 1.15, channel)
+    if channel == libm2k.ANALOG_IN_CHANNEL_1:
+        # CH2 should idle at 0V if we are testing CH1
+        is_idle_ok = is_idle_ok and are_values_within_range(data, -0.20, 0.20, libm2k.ANALOG_IN_CHANNEL_2)
+        assert is_idle_ok, "STEP3: CH2 should idle at 0V if we are testing CH1"
+    elif channel == libm2k.ANALOG_IN_CHANNEL_2:
+        is_idle_ok = is_idle_ok and are_values_within_range(data, -0.20, 0.20, libm2k.ANALOG_IN_CHANNEL_1)
+        assert is_idle_ok, "STEP3: CH1 should idle at 0V if we are testing CH2"
+    glitched = glitched or check_for_glitch(data)
+    if gen_reports:
+        plot_to_file(title=f"Last Sample Hold: {chn_str} - {sr_str} - Rising Ramp",
+                    data=data[0],
+                    data1=data[1],
+                    x_data=x_time,
+                    xlabel = x_label, 
+                    dir_name=subdir_name,
+                    y_lim=(-6, 6),
+                    filename=f"last_sample_hold_{chn_str}_{sr_str}_step3.png")
+    time.sleep(SLEEP)  # wait for the DAC output to settle with last sample
+    # 4: Falling
+    data = step_ramp_falling(channel, trig_chn, buffer_ramp_down)
+    # Shoud start with last sample from previous buffer
+    is_last_sample_hold_ok = is_last_sample_hold_ok and are_values_within_range(data[:, :2000], cfg["amplitude"] * 0.85, cfg["amplitude"] * 1.15, channel)
+    # Shoud hold last sample from new buffer
+    is_last_sample_hold_ok = is_last_sample_hold_ok and are_values_within_range(data[:, -2000:], -cfg["amplitude"] * 1.15, -cfg["amplitude"] * 0.85, channel)
+    if channel == libm2k.ANALOG_IN_CHANNEL_1:
+        # CH2 should idle at 0V if we are testing CH1
+        is_idle_ok = is_idle_ok and are_values_within_range(data, -0.20, 0.20, libm2k.ANALOG_IN_CHANNEL_2)
+        assert is_idle_ok, "STEP4: CH2 should idle at 0V if we are testing CH1"
+    elif channel == libm2k.ANALOG_IN_CHANNEL_2:
+        is_idle_ok = is_idle_ok and are_values_within_range(data, -0.20, 0.20, libm2k.ANALOG_IN_CHANNEL_1)
+        assert is_idle_ok, "STEP4: CH1 should idle at 0V if we are testing CH2"
+    glitched = glitched or check_for_glitch(data)
+    if gen_reports:
+        plot_to_file(title=f"Last Sample Hold: {chn_str} - {sr_str} - Falling Ramp",
+                    data=data[0],
+                    data1=data[1],
+                    x_data=x_time,
+                    xlabel = x_label, 
+                    dir_name=subdir_name,
+                    y_lim=(-6, 6),
+                    filename=f"last_sample_hold_{chn_str}_{sr_str}_step4.png")
+
+    aout.stop()
+    return glitched, is_last_sample_hold_ok, is_idle_ok

tests/helpers.py

@@ -1,4 +1,5 @@
 
+import numpy as np
 from pandas import DataFrame
 import matplotlib.pyplot as plt
 
@@ -27,7 +28,7 @@ def save_data_to_csv(csv_vals, csv_file):
     return
 
 
-def plot_to_file(title, data, dir_name, filename, xlabel=None, ylabel=None, data1=None, data_marked=None):
+def plot_to_file(title, data, dir_name, filename, xlabel=None, x_lim = None, ylabel=None, y_lim = None, data1=None, x_data = None, data_marked=None):
     # Saves the plots in a separate folder
     # Arguments:
     #    title  -- Title of the plot
@@ -40,7 +41,8 @@ def plot_to_file(title, data, dir_name, filename, xlabel=None, ylabel=None, data
     #    data_marked -- Data that represents specific points on the plot(default: {None})
     # plot the signals in a separate folder
     plt.title(title)
-    if xlabel is not None:  # if xlabel and ylabel are not specified there will be default values
+    # if xlabel and ylabel are not specified there will be default values
+    if xlabel is not None:  
         plt.xlabel(xlabel)
     else:
         plt.xlabel('Samples')
@@ -49,11 +51,51 @@ def plot_to_file(title, data, dir_name, filename, xlabel=None, ylabel=None, data
     else:
         plt.ylabel('Voltage [V]')
     plt.grid(visible=True)
-    plt.plot(data)  # if a second set of data must be printed (for ch0 and ch1 phase difference in this case)
+    # if x_data is not None, the plot will be displayed with the specified x_data
+    if x_data is not None:
+        plt.plot(x_data, data)
+    else:
+        plt.plot(data)
+    # if a second set of data must be printed (for ch0 and ch1 phase difference in this case)
     if data1 is not None:
-        plt.plot(data1)
+        if x_data is not None:
+            plt.plot(x_data, data1)
+        else:
+            plt.plot(data1)
+    # Optional configurations
+    if x_lim is not None:
+        plt.xlim(*x_lim)
+    if y_lim is not None:
+        plt.ylim(*y_lim)
     if data_marked is not None:
         plt.plot(data_marked, data[data_marked], 'xr')        
     plt.savefig(dir_name + "/" + filename)
     plt.close()
-    return
+    return
+
+
+def get_time_format(samples, sample_rate):
+    x_time = np.linspace(0, samples/sample_rate, samples)
+
+    if x_time[-1] < 1e-6:
+        x_time *= 1e9
+        x_label = "Time [ns]"
+    elif x_time[-1] < 1e-3:
+        x_time *= 1e6
+        x_label = "Time [us]"
+    elif x_time[-1] < 1:
+        x_time *= 1e3
+        x_label = "Time [ms]"
+    else:
+        x_label = "Time [s]"
+    return x_time, x_label
+
+
+def get_sample_rate_display_format(sample_rate):
+    if sample_rate < 1e3:
+        return f"{sample_rate:.2f} Hz"
+    if sample_rate < 1e6:
+        return f"{sample_rate/1e3:.2f} KHz"
+    if sample_rate < 1e9:
+        return f"{sample_rate/1e6:.2f} MHz"
+    return f"{sample_rate/1e9:.2f} GHz"

tests/m2k_analog_test.py

@@ -3,7 +3,7 @@
 import libm2k
 
 from shapefile import shape_gen, ref_shape_gen, shape_name
-from analog_functions import test_amplitude, test_shape, phase_diff_ch0_ch1, test_offset, test_analog_trigger, \
+from analog_functions import get_experiment_config_for_sample_hold, test_amplitude, test_last_sample_hold, test_shape, phase_diff_ch0_ch1, test_offset, test_analog_trigger, \
     test_voltmeter_functionality, test_kernel_buffers, test_buffer_transition_glitch
 from analog_functions import noncyclic_buffer_test, set_samplerates_for_shapetest, set_trig_for_cyclicbuffer_test, \
     test_calibration
@@ -15,6 +15,8 @@
 import logger
 from repeat_test import repeat
 
+from helpers import get_sample_rate_display_format
+
 
 class A_AnalogTests(unittest.TestCase):
     # Class Where are defined all test methods for AnalogIn, AnalogOut, AnalogTrigger
@@ -251,4 +253,28 @@ def test_buffer_transition_glitch(self):
                 num_glitches = test_buffer_transition_glitch(channel, ain, aout, trig, waveform)
 
                 with self.subTest(msg='Test buffer transition glitch: ' + waveform + ' on ch' + str(channel)):
-                    self.assertEqual(num_glitches, 0, 'Found ' + str(num_glitches) + ' glitches on channel ' + str(channel))
+                    self.assertEqual(num_glitches, 0, 'Found ' + str(num_glitches) + ' glitches on channel ' + str(channel))
+
+    @unittest.skipIf(ctx.getFirmwareVersion() < 'v0.33',
+                    'The sample and hold feature is available starting with firmware v0.33. Note: v0.32 had a glitch that is handled in this test.')
+    def test_last_sample_hold(self):
+        # Tests the last sample hold functionality for different channels and DAC sample rates.
+        # This test iterates over different channels (each channel individually and both channels together) 
+        # and then tests the last sample hold functionality. When testing both channels together, 'None' 
+        # is used to denote this case. 
+        # It verifies that the last sample is held correctly and that there are no glitches in the output signal in between the last sample and a new push.
+
+        for channel in [libm2k.ANALOG_IN_CHANNEL_1, libm2k.ANALOG_IN_CHANNEL_2, None]:
+            for dac_sr in [75_000_000, 7_500_000, 750_000, 75_000, 7_500]:
+                cfg = get_experiment_config_for_sample_hold(dac_sr)
+                sr_format = get_sample_rate_display_format(cfg.get("dac_sr"))
+                chn_str = "both_channels" if channel is None else f"CH{channel}"
+                reset.analog_in(ain)
+                reset.analog_out(aout)
+                reset.trigger(trig)
+                has_glitch, is_last_sample_hold_ok, is_idle_ok = test_last_sample_hold(ain, aout, trig, ctx, cfg, channel)
+                with self.subTest(msg='Test last sample hold on ' + str(chn_str) + ' with DAC SR ' + str(cfg.get("dac_sr"))):
+                    self.assertEqual(has_glitch, False, f'Found glitches on {chn_str} with DAC SR {sr_format}')
+                    self.assertEqual(is_last_sample_hold_ok, True, f'Last sample hold failed on {chn_str} with DAC SR {sr_format}')
+                    self.assertEqual(is_last_sample_hold_ok, True, f'Last sample hold failed on {chn_str} with DAC SR {sr_format}')
+                    self.assertEqual(is_idle_ok, True, 'Test idle condition failed')