Create usbdrdaqExamples/usbdrdaqPhBlockExample.py

Author: neil.hamilton

usbdrdaqExamples/usbdrdaqPhBlockExample.py

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+#
+# Copyright (C) 2020 Pico Technology Ltd. See LICENSE file for terms.
+#
+# USBDRDAQ SCOPE BLOCK MODE EXAMPLE
+# This example opens a UsbDrDaq driver device, sets up the scope channel and a trigger then collects a single block of data.
+# This data is then plotted as mV against time in ns.
+
+import ctypes
+import time
+from picosdk.usbDrDaq import usbDrDaq as drDaq
+import numpy as np
+import matplotlib.pyplot as plt
+from picosdk.functions import adc2mV, assert_pico_ok
+
+# Create chandle and status ready for use
+status = {}
+chandle = ctypes.c_int16()
+
+# Opens the device
+status["openunit"] = drDaq.UsbDrDaqOpenUnit(ctypes.byref(chandle))
+assert_pico_ok(status["openunit"])
+
+# Set sample interval
+us_for_block = ctypes.c_int32(1000)
+ideal_no_of_samples = 1000
+channels = ctypes.c_int32(drDaq.USB_DRDAQ_INPUTS["USB_DRDAQ_CHANNEL_PH"])
+no_of_channels = 1
+status["setInterval"] = drDaq.UsbDrDaqSetInterval(chandle, ctypes.byref(us_for_block), ideal_no_of_samples, ctypes.byref(channels), no_of_channels)
+assert_pico_ok(status["setInterval"])
+
+# Find scaling information
+channel = drDaq.USB_DRDAQ_INPUTS["USB_DRDAQ_CHANNEL_PH"]
+nScales = ctypes.c_int16(0)
+currentScale = ctypes.c_int16(0)
+names = (ctypes.c_char*256)()
+namesSize = 256
+status["getscalings"] = drDaq.UsbDrDaqGetScalings(chandle, channel, ctypes.byref(nScales), ctypes.byref(currentScale), ctypes.byref(names), namesSize)
+assert_pico_ok(status["getscalings"])
+
+print(nScales.value)
+print(currentScale.value)
+print(names.value)
+
+# Set channel scaling 
+scalingNumber = 0 # pH scaling
+status["setscaling"] = drDaq.UsbDrDaqSetScalings(chandle, channel, scalingNumber)
+assert_pico_ok(status["setscaling"])
+
+# Set temperature compenstation
+enabled = 1
+status["phTemperatureCompensation"] = drDaq.UsbDrDaqPhTemperatureCompensation(chandle, enabled)
+assert_pico_ok(status["phTemperatureCompensation"])
+
+# Run block capture
+method = drDaq.USB_DRDAQ_BLOCK_METHOD["BM_SINGLE"]
+status["run"] = drDaq.UsbDrDaqRun(chandle, ideal_no_of_samples, method)
+assert_pico_ok(status["run"])
+
+ready = ctypes.c_int16(0)
+
+while ready.value == 0:
+    status["ready"] = drDaq.UsbDrDaqReady(chandle, ctypes.byref(ready))
+    print(ready.value)
+    time.sleep(0.1)
+
+# Retrieve data from device
+values = (ctypes.c_float * ideal_no_of_samples)()
+noOfValues = ctypes.c_uint32(ideal_no_of_samples)
+overflow = ctypes.c_uint16(0)
+triggerIndex = ctypes.c_uint32(0)
+status["getvaluesF"] = drDaq.UsbDrDaqGetValuesF(chandle, ctypes.byref(values), ctypes.byref(noOfValues), ctypes.byref(overflow), ctypes.byref(triggerIndex))
+assert_pico_ok(status["getvaluesF"])
+
+# generate time data
+time = np.linspace(0, us_for_block, ideal_no_of_samples)
+
+# plot the data
+plt.plot(time, values[:])
+plt.xlabel('Time (ns)')
+plt.ylabel('pH')
+plt.show()
+
+
+# Disconnect the scope
+# handle = chandle
+status["close"] = drDaq.UsbDrDaqCloseUnit(chandle)
+assert_pico_ok(status["close"])
+
+# Display status returns
+print(status)