====== Getting Started with WaveForms SDK ======
WaveForms SDK is a set of tools provided within the WaveForms installation that are used to develop custom software solutions that use Digilent Test and Measurement devices. The WaveForms SDK API is available in several programming languages, making it easy to use across many different platforms.
Normally, Test and Measurement devices are controlled and configured through the WaveForms application with a personal computer. Such a setup may be impossible in a given context, or an amount of automated signal measurement may be required beyond what WaveForms' scripting environment allows. WaveForms SDK gives the necessary tools to help craft the perfect solution for any problem.
This guide demonstrates the usage of some basic instruments and presents some patterns to help develop your own application. It is written with Python in mind, but users of other languages will still find it useful to illustrate the principles of working with the SDK.
For an up-to-date version of the scripts, check the [[https://github.com/Digilent/WaveForms-SDK-Getting-Started-PY|GitHub repository, Python]].
The GitHub material used by this guide has not been been updated since 2022. Newer hardware, such as the Analog Discovery 3, and additional software features that have been added since that time are not directly supported in Python modules and test examples provided by the GitHub material.
Alternate, fully supported examples for each supported programming language, maintained by the WaveForms development team, are provided with the WaveForms SDK download and may be found at the following locations:
* Windows 32-bit: **C:\Program Files\Digilent\WaveFormsSDK\samples**
* Windows 64-bit: **C:\Program Files (x86)\Digilent\WaveFormsSDK\samples**
* Linux: **/usr/share/digilent/waveforms/samples**
* macOS: **/Applications/WaveForms.app/Contents/Resources/SDK/samples**
The Python examples included with the WaveForms SDK download do not use any wrapper modules. However, an overview of how some of the underlying ctypes functions might be used to create modules is provided in the four numbered __[[waveforms-sdk-getting-started#workflow|Workflow]]__ sections further down in this document.
----
===== Inventory =====
* A Digilent Test & Measurement Device
* [[test-and-measurement:analog-discovery-3:start|Analog Discovery 3]]
* [[test-and-measurement:discovery-power-supply-3340:start|Discovery Power Supply (DPS3340)]]
* [[test-and-measurement:analog-discovery-pro-5250:start|]]
* [[test-and-measurement:analog-discovery-pro-3x50:start|]]
* [[test-and-measurement:analog-discovery-pro-2230:start|Analog Discovery Pro (ADP2230)]]
* [[test-and-measurement:analog-discovery-studio:start|]]
* [[test-and-measurement:analog-discovery-2:start|]]
* [[test-and-measurement:analog-discovery:start|]]
* [[test-and-measurement:digital-discovery:start|]]
* A Computer with WaveForms Installed
* Both the WaveForms application and WaveForms SDK can be installed by following the [[software:waveforms:waveforms-3:getting-started-guide]].
----
===== SDK Overview =====
WaveForms SDK is included with WaveForms and is installed alongside the application. The SDK is available to use with C/C++, C#, Python, and Visual Basic through a dynamic library (a module that contains data that can be used by other applications).
Another important file is the one that contains the definition of all constants. If you want to use the SDK from Python, this file is a Python module, while for C/C++ applications, the constants are defined in a header file.
----
===== Workflow =====
==== 1. Importing the Constants and Loading the Dynamic Library ====
The WaveForms SDK Python functions use C-compatible data types, so along with the dynamic library and the module containing the constants, you will also need the **ctypes** module, which is installed together with Python by default.
As the first step of your project import the **dwfconstants.py** file to your project directory (it is located among the sample codes, in the **py** folder), then load the necessary modules and the dynamic library.
import ctypes # import the C compatible data types
from sys import platform, path # this is needed to check the OS type and get the PATH
from os import sep # OS specific file path separators
# load the dynamic library, get constants path (the path is OS specific)
if platform.startswith("win"):
# on Windows
dwf = ctypes.cdll.dwf
constants_path = "C:" + sep + "Program Files (x86)" + sep + "Digilent" + sep + "WaveFormsSDK" + sep + "samples" + sep + "py"
elif platform.startswith("darwin"):
# on macOS
lib_path = sep + "Library" + sep + "Frameworks" + sep + "dwf.framework" + sep + "dwf"
dwf = ctypes.cdll.LoadLibrary(lib_path)
constants_path = sep + "Applications" + sep + "WaveForms.app" + sep + "Contents" + sep + "Resources" + sep + "SDK" + sep + "samples" + sep + "py"
else:
# on Linux
dwf = ctypes.cdll.LoadLibrary("libdwf.so")
constants_path = sep + "usr" + sep + "share" + sep + "digilent" + sep + "waveforms" + sep + "samples" + sep + "py"
# import constants
path.append(constants_path)
import dwfconstants as constants
----
==== 2. Connecting the Test & Measurement Device ====
The next step is to "open" your device. If you have only one Test & Measurement device connected, the simplest method is to ask the WaveForms SDK to connect to the first available device.
Opening a specific device and retrieving the name of the connected device is also possible (for more information, check the WaveForms SDK examples, or the GitHub repository).
class data:
"""
stores the device handle and the device name
"""
handle = ctypes.c_int(0)
name = ""
def open():
"""
open the first available device
"""
# this is the device handle - it will be used by all functions to "address" the connected device
device_handle = ctypes.c_int()
# connect to the first available device
dwf.FDwfDeviceOpen(ctypes.c_int(-1), ctypes.byref(device_handle))
data.handle = device_handle
return data
----
==== 3. Using Instruments ====
The code snippets in this section present basic functionality of some instruments for some devices. For more possibilities (advanced features and more instruments) check the documentation of the WaveForms SDK, the available sample scripts and the GitHub repository.
--> 3.1 Oscilloscope #
=== 3.1.1 Initialize the Scope ===
Before measuring with the oscilloscope, it must be set up. Change the values to fit your needs.
class data:
""" stores the sampling frequency and the buffer size """
sampling_frequency = 20e06
buffer_size = 8192
def open(device_data, sampling_frequency=20e06, buffer_size=8192, offset=0, amplitude_range=5):
"""
initialize the oscilloscope
parameters: - device data
- sampling frequency in Hz, default is 20MHz
- buffer size, default is 8192
- offset voltage in Volts, default is 0V
- amplitude range in Volts, default is ±5V
"""
# enable all channels
dwf.FDwfAnalogInChannelEnableSet(device_data.handle, ctypes.c_int(0), ctypes.c_bool(True))
# set offset voltage (in Volts)
dwf.FDwfAnalogInChannelOffsetSet(device_data.handle, ctypes.c_int(0), ctypes.c_double(offset))
# set range (maximum signal amplitude in Volts)
dwf.FDwfAnalogInChannelRangeSet(device_data.handle, ctypes.c_int(0), ctypes.c_double(amplitude_range))
# set the buffer size (data point in a recording)
dwf.FDwfAnalogInBufferSizeSet(device_data.handle, ctypes.c_int(buffer_size))
# set the acquisition frequency (in Hz)
dwf.FDwfAnalogInFrequencySet(device_data.handle, ctypes.c_double(sampling_frequency))
# disable averaging (for more info check the documentation)
dwf.FDwfAnalogInChannelFilterSet(device_data.handle, ctypes.c_int(-1), constants.filterDecimate)
data.sampling_frequency = sampling_frequency
data.buffer_size = buffer_size
return
=== 3.1.2 Measure a Voltage ===
You can measure voltages, like with the Voltmeter instrument in WaveForms.
def measure(device_data, channel):
"""
measure a voltage
parameters: - device data
- the selected oscilloscope channel (1-2, or 1-4)
returns: - the measured voltage in Volts
"""
# set up the instrument
dwf.FDwfAnalogInConfigure(device_data.handle, ctypes.c_bool(False), ctypes.c_bool(False))
# read data to an internal buffer
dwf.FDwfAnalogInStatus(device_data.handle, ctypes.c_bool(False), ctypes.c_int(0))
# extract data from that buffer
voltage = ctypes.c_double() # variable to store the measured voltage
dwf.FDwfAnalogInStatusSample(device_data.handle, ctypes.c_int(channel - 1), ctypes.byref(voltage))
# store the result as float
voltage = voltage.value
return voltage
=== 3.1.3 Record a Signal ===
The most important feature of the oscilloscope is, that it can record signals. The recorded voltages can be stored in a list.
def record(device_data, channel):
"""
record an analog signal
parameters: - device data
- the selected oscilloscope channel (1-2, or 1-4)
returns: - buffer - a list with the recorded voltages
- time - a list with the time moments for each voltage in seconds (with the same index as "buffer")
"""
# set up the instrument
dwf.FDwfAnalogInConfigure(device_data.handle, ctypes.c_bool(False), ctypes.c_bool(True))
# read data to an internal buffer
while True:
status = ctypes.c_byte() # variable to store buffer status
dwf.FDwfAnalogInStatus(device_data.handle, ctypes.c_bool(True), ctypes.byref(status))
# check internal buffer status
if status.value == constants.DwfStateDone.value:
# exit loop when ready
break
# copy buffer
buffer = (ctypes.c_double * data.buffer_size)() # create an empty buffer
dwf.FDwfAnalogInStatusData(device_data.handle, ctypes.c_int(channel - 1), buffer, ctypes.c_int(data.buffer_size))
# calculate aquisition time
time = range(0, data.buffer_size)
time = [moment / data.sampling_frequency for moment in time]
# convert into list
buffer = [float(element) for element in buffer]
return buffer, time
=== 3.1.4 Reset the Scope ===
After usage, reset the oscilloscope to the default settings.
def close(device_data):
"""
reset the scope
"""
dwf.FDwfAnalogInReset(device_data.handle)
return
<--
--> 3.2 Waveform Generator #
=== 3.2.1 Generate a Signal ===
Use the waveform generator to generate different signals.
You can define custom function names, to make the usage of the function easier.
class function:
""" function names """
custom = constants.funcCustom
sine = constants.funcSine
square = constants.funcSquare
triangle = constants.funcTriangle
noise = constants.funcNoise
dc = constants.funcDC
pulse = constants.funcPulse
trapezium = constants.funcTrapezium
sine_power = constants.funcSinePower
ramp_up = constants.funcRampUp
ramp_down = constants.funcRampDown
def generate(device_data, channel, function, offset, frequency=1e03, amplitude=1, symmetry=50, wait=0, run_time=0, repeat=0, data=[]):
"""
generate an analog signal
parameters: - device data
- the selected wavegen channel (1-2)
- function - possible: custom, sine, square, triangle, noise, ds, pulse, trapezium, sine_power, ramp_up, ramp_down
- offset voltage in Volts
- frequency in Hz, default is 1KHz
- amplitude in Volts, default is 1V
- signal symmetry in percentage, default is 50%
- wait time in seconds, default is 0s
- run time in seconds, default is infinite (0)
- repeat count, default is infinite (0)
- data - list of voltages, used only if function=custom, default is empty
"""
# enable channel
channel = ctypes.c_int(channel - 1)
dwf.FDwfAnalogOutNodeEnableSet(device_data.handle, channel, constants.AnalogOutNodeCarrier, ctypes.c_bool(True))
# set function type
dwf.FDwfAnalogOutNodeFunctionSet(device_data.handle, channel, constants.AnalogOutNodeCarrier, function)
# load data if the function type is custom
if function == constants.funcCustom:
data_length = len(data)
buffer = (ctypes.c_double * data_length)()
for index in range(0, len(buffer)):
buffer[index] = ctypes.c_double(data[index])
dwf.FDwfAnalogOutNodeDataSet(device_data.handle, channel, constants.AnalogOutNodeCarrier, buffer, ctypes.c_int(data_length))
# set frequency
dwf.FDwfAnalogOutNodeFrequencySet(device_data.handle, channel, constants.AnalogOutNodeCarrier, ctypes.c_double(frequency))
# set amplitude or DC voltage
dwf.FDwfAnalogOutNodeAmplitudeSet(device_data.handle, channel, constants.AnalogOutNodeCarrier, ctypes.c_double(amplitude))
# set offset
dwf.FDwfAnalogOutNodeOffsetSet(device_data.handle, channel, constants.AnalogOutNodeCarrier, ctypes.c_double(offset))
# set symmetry
dwf.FDwfAnalogOutNodeSymmetrySet(device_data.handle, channel, constants.AnalogOutNodeCarrier, ctypes.c_double(symmetry))
# set running time limit
dwf.FDwfAnalogOutRunSet(device_data.handle, channel, ctypes.c_double(run_time))
# set wait time before start
dwf.FDwfAnalogOutWaitSet(device_data.handle, channel, ctypes.c_double(wait))
# set number of repeating cycles
dwf.FDwfAnalogOutRepeatSet(device_data.handle, channel, ctypes.c_int(repeat))
# start
dwf.FDwfAnalogOutConfigure(device_data.handle, channel, ctypes.c_bool(True))
return
=== 3.2.2 Reset the Wavegen ===
After usage, reset the wavegen to the default settings.
def close(device_data, channel=0):
"""
reset a wavegen channel, or all channels (channel=0)
"""
channel = ctypes.c_int(channel - 1)
dwf.FDwfAnalogOutReset(device_data.handle, channel)
return
<--
--> 3.3 Power Supplies #
--> 3.3.1 Analog Discovery 3 Supplies #
The Analog Discovery 3 has variable positive and negative supplies to set voltage levels.
def _switch_variable_(device_data, master_state, positive_state, negative_state, positive_voltage, negative_voltage):
"""
turn the power supplies on/off
parameters: - device data
- master switch - True = on, False = off
- positive supply switch - True = on, False = off
- negative supply switch - True = on, False = off
- positive supply voltage in Volts
- negative supply voltage in Volts
"""
# set positive voltage
positive_voltage = max(0, min(5, positive_voltage))
dwf.FDwfAnalogIOChannelNodeSet(device_data.handle, ctypes.c_int(0), ctypes.c_int(1), ctypes.c_double(positive_voltage))
# set negative voltage
negative_voltage = max(-5, min(0, negative_voltage))
dwf.FDwfAnalogIOChannelNodeSet(device_data.handle, ctypes.c_int(1), ctypes.c_int(1), ctypes.c_double(negative_voltage))
# enable/disable the positive supply
dwf.FDwfAnalogIOChannelNodeSet(device_data.handle, ctypes.c_int(0), ctypes.c_int(0), ctypes.c_int(positive_state))
# enable the negative supply
dwf.FDwfAnalogIOChannelNodeSet(device_data.handle, ctypes.c_int(1), ctypes.c_int(0), ctypes.c_int(negative_state))
# start/stop the supplies - master switch
dwf.FDwfAnalogIOEnableSet(device_data.handle, ctypes.c_int(master_state))
return
<--
--> 3.3.2 Analog Discovery 2 and Analog Discovery Studio Supplies #
These devices have variable positive and negative supplies, so a voltage level can also be set.
def _switch_variable_(device_data, master_state, positive_state, negative_state, positive_voltage, negative_voltage):
"""
turn the power supplies on/off
parameters: - device data
- master switch - True = on, False = off
- positive supply switch - True = on, False = off
- negative supply switch - True = on, False = off
- positive supply voltage in Volts
- negative supply voltage in Volts
"""
# set positive voltage
positive_voltage = max(0, min(5, positive_voltage))
dwf.FDwfAnalogIOChannelNodeSet(device_data.handle, ctypes.c_int(0), ctypes.c_int(1), ctypes.c_double(positive_voltage))
# set negative voltage
negative_voltage = max(-5, min(0, negative_voltage))
dwf.FDwfAnalogIOChannelNodeSet(device_data.handle, ctypes.c_int(1), ctypes.c_int(1), ctypes.c_double(negative_voltage))
# enable/disable the positive supply
dwf.FDwfAnalogIOChannelNodeSet(device_data.handle, ctypes.c_int(0), ctypes.c_int(0), ctypes.c_int(positive_state))
# enable the negative supply
dwf.FDwfAnalogIOChannelNodeSet(device_data.handle, ctypes.c_int(1), ctypes.c_int(0), ctypes.c_int(negative_state))
# start/stop the supplies - master switch
dwf.FDwfAnalogIOEnableSet(device_data.handle, ctypes.c_int(master_state))
return
<--
--> 3.3.3 Analog Discovery (Legacy) Supplies #
The Analog Discovery has only fixed supplies, so just a limited number of functions are available.
def _switch_fixed_(device_data, master_state, positive_state, negative_state):
"""
turn the power supplies on/off
parameters: - device data
- master switch - True = on, False = off
- positive supply switch - True = on, False = off
- negative supply switch - True = on, False = off
"""
# enable/disable the positive supply
dwf.FDwfAnalogIOChannelNodeSet(device_data.handle, ctypes.c_int(0), ctypes.c_int(0), ctypes.c_int(positive_state))
# enable the negative supply
dwf.FDwfAnalogIOChannelNodeSet(device_data.handle, ctypes.c_int(1), ctypes.c_int(0), ctypes.c_int(negative_state))
# start/stop the supplies - master switch
dwf.FDwfAnalogIOEnableSet(device_data.handle, ctypes.c_int(master_state))
return
<--
--> 3.3.4 Analog Discovery Pro 3X50 and Digital Discovery Supplies #
Devices with digital supplies have only positive voltage supplies with a variable voltage level between 1.2 and 3.3 Volts.
def _switch_digital_(device_data, master_state, voltage):
"""
turn the power supplies on/off
parameters: - device data
- master switch - True = on, False = off
- supply voltage in Volts
"""
# set supply voltage
voltage = max(1.2, min(3.3, voltage))
dwf.FDwfAnalogIOChannelNodeSet(device_data.handle, ctypes.c_int(0), ctypes.c_int(0), ctypes.c_double(voltage))
# start/stop the supplies - master switch
dwf.FDwfAnalogIOEnableSet(device_data.handle, ctypes.c_int(master_state))
return
<--
--> 3.3.5 Analog Discovery Pro 5250 6V Power Supply #
You can set not only the voltage for the 6V power supply on the Analog Discovery 5250, but also the current limit, up to 1A.
def _switch_6V_(device_data, master_state, voltage, current=1):
"""
turn the 6V supply on the ADP5250 on/off
parameters: - master switch - True = on, False = off
- voltage in volts between 0-6
- current in amperes between 0-1
"""
# set the voltage
voltage = max(0, min(6, voltage))
dwf.FDwfAnalogIOChannelNodeSet(device_data.handle, ctypes.c_int(0), ctypes.c_int(1), ctypes.c_double(voltage))
# set the current
current = max(0, min(1, current))
dwf.FDwfAnalogIOChannelNodeSet(device_data.handle, ctypes.c_int(0), ctypes.c_int(2), ctypes.c_double(current))
# start/stop the supply - master switch
dwf.FDwfAnalogIOChannelNodeSet(device_data.handle, ctypes.c_int(0), ctypes.c_int(0), ctypes.c_double(float(master_state)))
dwf.FDwfAnalogIOEnableSet(device_data.handle, ctypes.c_int(master_state))
return
<--
--> 3.3.6 Analog Discovery Pro 5250 25V Power Supplies #
The positive and negative isolated 25V power supplies are similar to the 6V one, but with a maximum current limit of 500mA.
def _switch_25V_(device_data, positive_state, negative_state, positive_voltage, negative_voltage, positive_current=0.5, negative_current=-0.5):
"""
turn the 25V power supplies on/off on the ADP5250
parameters: - positive supply switch - True = on, False = off
- negative supply switch - True = on, False = off
- positive supply voltage in Volts
- negative supply voltage in Volts
- positive supply current limit
- negative supply current limit
"""
# set positive voltage
positive_voltage = max(0, min(25, positive_voltage))
dwf.FDwfAnalogIOChannelNodeSet(device_data.handle, ctypes.c_int(1), ctypes.c_int(1), ctypes.c_double(positive_voltage))
# set negative voltage
negative_voltage *= -1
dwf.FDwfAnalogIOChannelNodeSet(device_data.handle, ctypes.c_int(2), ctypes.c_int(1), ctypes.c_double(negative_voltage))
# set positive current limit
positive_current = max(0, min(0.5, positive_current))
dwf.FDwfAnalogIOChannelNodeSet(device_data.handle, ctypes.c_int(1), ctypes.c_int(2), ctypes.c_double(positive_current))
# set negative current limit
negative_current *= -1
dwf.FDwfAnalogIOChannelNodeSet(device_data.handle, ctypes.c_int(2), ctypes.c_int(2), ctypes.c_double(negative_current))
# enable/disable the supplies
dwf.FDwfAnalogIOChannelNodeSet(device_data.handle, ctypes.c_int(1), ctypes.c_int(0), ctypes.c_double(float(positive_state)))
dwf.FDwfAnalogIOChannelNodeSet(device_data.handle, ctypes.c_int(2), ctypes.c_int(0), ctypes.c_double(float(negative_state)))
# master switch
dwf.FDwfAnalogIOEnableSet(device_data.handle, ctypes.c_int(positive_state or negative_state))
return
<--
=== 3.3.7 Wrapper Function ===
To make the usage of the above functions easier, you can create a wrapper function, which is able to call the function you need (if the device name is set).
class data:
""" power supply parameters """
master_state = False # master switch
state = False # digital/6V/positive supply state
positive_state = False # positive supply switch
negative_state = False # negative supply switch
positive_voltage = 0 # positive supply voltage
negative_voltage = 0 # negative supply voltage
voltage = 0 # digital/positive supply voltage
positive_current = 0 # positive supply current
negative_current = 0 # negative supply current
current = 0 # digital/6V supply current
def switch(device_data, supplies_data):
"""
turn the power supplies on/off
parameters: - device data
- class containing supplies data:
- master_state
- state and/or positive_state and negative_state
- voltage and/or positive_voltage and negative_voltage
- current and/or positive_current and negative_current
"""
if device_data.name == "Analog Discovery":
# switch fixed supplies on AD
supply_state = supplies_data.state or supplies_data.positive_state
_switch_fixed_(device_data, supplies_data.master_state, supply_state, supplies_data.negative_state)
elif device_data.name == "Analog Discovery 2" or device_data.name == "Analog Discovery Studio":
# switch variable supplies on AD2
supply_state = supplies_data.state or supplies_data.positive_state
supply_voltage = supplies_data.voltage + supplies_data.positive_voltage
_switch_variable_(device_data, supplies_data.master_state, supply_state, supplies_data.negative_state, supply_voltage, supplies_data.negative_voltage)
elif device_data.name == "Digital Discovery" or device_data.name == "Analog Discovery Pro 3X50":
# switch the digital supply on DD, or ADP3x50
supply_state = supplies_data.master_state and (supplies_data.state or supplies_data.positive_state)
supply_voltage = supplies_data.voltage + supplies_data.positive_voltage
_switch_digital_(device_data, supply_state, supply_voltage)
elif device_data.name == "Analog Discovery Pro 5250":
# switch the 6V supply on ADP5250
supply_state = supplies_data.master_state and supplies_data.state
_switch_6V_(device_data, supply_state, supplies_data.voltage, supplies_data.current)
# switch the 25V supplies on ADP5250
supply_positive_state = supplies_data.master_state and supplies_data.positive_state
supply_negative_state = supplies_data.master_state and supplies_data.negative_state
_switch_25V_(device_data, supply_positive_state, supply_negative_state, supplies_data.positive_voltage, supplies_data.negative_voltage, supplies_data.positive_current, supplies_data.negative_current)
return
=== 3.3.8 Reset the Supplies ===
After usage, reset the supplies to the default settings.
def close(device_data):
"""
reset the supplies
"""
dwf.FDwfAnalogIOReset(device_data.handle)
return
<--
--> 3.4 Digital Multimeter - Only on ADP5250 #
=== 3.4.1 Initialize the DMM ===
Before measuring with the digital multimeter, it must be enabled.
def open(device_data):
"""
initialize the digital multimeter
"""
# enable the DMM
dwf.FDwfAnalogIOChannelNodeSet(device_data.handle, ctypes.c_int(3), ctypes.c_int(0), ctypes.c_double(1.0))
return
=== 3.4.2 Measure With the DMM ===
You can use the digital multimeter to measure AC, or DC voltages (in Volts), with an input impedance of 10MΩ, or 10GΩ, low (<100mA), or high AC, or DC currents (up to 10A), resistance, conductance, temperature and more, with automatic, or fixed range.
def measure(device_data, mode, ac=False, range=0, high_impedance=False):
"""
measure a voltage/current/resistance/continuity/temperature
parameters: - device data
- mode: "voltage", "low current", "high current", "resistance", "continuity", "diode", "temperature"
- ac: True means AC value, False means DC value, default is DC
- range: voltage/current/resistance/temperature range, 0 means auto, default is auto
- high_impedance: input impedance for DC voltage measurement, False means 10MΩ, True means 10GΩ, default is 10MΩ
returns: - the measured value in V/A/Ω/°C, or None on error
"""
# set voltage mode
if mode == "voltage":
# set coupling
if ac:
dwf.FDwfAnalogIOChannelNodeSet(device_data.handle, ctypes.c_int(3), ctypes.c_int(1), constants.DwfDmmACVoltage)
else:
dwf.FDwfAnalogIOChannelNodeSet(device_data.handle, ctypes.c_int(3), ctypes.c_int(1), constants.DwfDmmDCVoltage)
# set input impedance
if high_impedance:
dwf.FDwfAnalogIOChannelNodeSet(device_data.handle, ctypes.c_int(3), ctypes.c_int(5), ctypes.c_double(1))
else:
dwf.FDwfAnalogIOChannelNodeSet(device_data.handle, ctypes.c_int(3), ctypes.c_int(5), ctypes.c_double(0))
# set high current mode
elif mode == "high current":
# set coupling
if ac:
dwf.FDwfAnalogIOChannelNodeSet(device_data.handle, ctypes.c_int(3), ctypes.c_int(1), constants.DwfDmmACCurrent)
else:
dwf.FDwfAnalogIOChannelNodeSet(device_data.handle, ctypes.c_int(3), ctypes.c_int(1), constants.DwfDmmDCCurrent)
# set low current mode
elif mode == "low current":
# set coupling
if ac:
dwf.FDwfAnalogIOChannelNodeSet(device_data.handle, ctypes.c_int(3), ctypes.c_int(1), constants.DwfDmmACLowCurrent)
else:
dwf.FDwfAnalogIOChannelNodeSet(device_data.handle, ctypes.c_int(3), ctypes.c_int(1), constants.DwfDmmDCLowCurrent)
# set resistance mode
elif mode == "resistance":
dwf.FDwfAnalogIOChannelNodeSet(device_data.handle, ctypes.c_int(3), ctypes.c_int(1), constants.DwfDmmResistance)
# set continuity mode
elif mode == "continuity":
dwf.FDwfAnalogIOChannelNodeSet(device_data.handle, ctypes.c_int(3), ctypes.c_int(1), constants.DwfDmmContinuity)
# set diode mode
elif mode == "diode":
dwf.FDwfAnalogIOChannelNodeSet(device_data.handle, ctypes.c_int(3), ctypes.c_int(1), constants.DwfDmmDiode)
# set temperature mode
elif mode == "temperature":
dwf.FDwfAnalogIOChannelNodeSet(device_data.handle, ctypes.c_int(3), ctypes.c_int(1), constants.DwfDmmTemperature)
# set range
dwf.FDwfAnalogIOChannelNodeSet(device_data.handle, ctypes.c_int(3), ctypes.c_int(2), ctypes.c_double(range))
# fetch analog I/O status
if dwf.FDwfAnalogIOStatus(device_data.handle) == 0:
# signal error
return None
# get reading
measurement = ctypes.c_double()
dwf.FDwfAnalogIOChannelNodeStatus(device_data.handle, ctypes.c_int(3), ctypes.c_int(3), ctypes.byref(measurement))
return measurement.value
=== 3.4.3 Reset the DMM ===
After usage, reset the instrument to the default settings.
def close(device_data):
"""
reset the instrument
"""
# disable the DMM
dwf.FDwfAnalogIOChannelNodeSet(device_data.handle, ctypes.c_int(3), ctypes.c_int(0), ctypes.c_double(0))
# reset the instrument
dwf.FDwfAnalogIOReset(device_data.handle)
return
<--
--> 3.5 Logic Analyzer #
=== 3.5.1 Initialize the Logic Analyzer ===
Before measuring with the logic analyzer, it must be set up. Change the values to fit your needs.
class data:
""" stores the sampling frequency and the buffer size """
sampling_frequency = 100e06
buffer_size = 4096
def open(device_data, sampling_frequency=100e06, buffer_size=4096):
"""
initialize the logic analyzer
parameters: - device data
- sampling frequency in Hz, default is 100MHz
- buffer size, default is 4096
"""
# get internal clock frequency
internal_frequency = ctypes.c_double()
dwf.FDwfDigitalInInternalClockInfo(device_data.handle, ctypes.byref(internal_frequency))
# set clock frequency divider (needed for lower frequency input signals)
dwf.FDwfDigitalInDividerSet(device_data.handle, ctypes.c_int(int(internal_frequency.value / sampling_frequency)))
# set 16-bit sample format
dwf.FDwfDigitalInSampleFormatSet(device_data.handle, ctypes.c_int(16))
# set buffer size
dwf.FDwfDigitalInBufferSizeSet(device_data.handle, ctypes.c_int(buffer_size))
data.sampling_frequency = sampling_frequency
data.buffer_size = buffer_size
return
=== 3.5.2 Record Logic Signals ===
Record logic signals in a list of lists, then select the one specific for the required DIO line.
def record(device_data, channel):
"""
initialize the logic analyzer
parameters: - device data
- channel - the selected DIO line number
returns: - buffer - a list with the recorded logic values
- time - a list with the time moments for each value in seconds (with the same index as "buffer")
"""
# set up the instrument
dwf.FDwfDigitalInConfigure(device_data.handle, ctypes.c_bool(False), ctypes.c_bool(True))
# read data to an internal buffer
while True:
status = ctypes.c_byte() # variable to store buffer status
dwf.FDwfDigitalInStatus(device_data.handle, ctypes.c_bool(True), ctypes.byref(status))
if status.value == constants.stsDone.value:
# exit loop when finished
break
# get samples
buffer = (ctypes.c_uint16 * data.buffer_size)()
dwf.FDwfDigitalInStatusData(device_data.handle, buffer, ctypes.c_int(2 * data.buffer_size))
# convert buffer to list of lists of integers
buffer = [int(element) for element in buffer]
result = [[] for _ in range(16)]
for point in buffer:
for index in range(16):
result[index].append(point & (1 << index))
# calculate acquisition time
time = range(0, data.buffer_size)
time = [moment / data.sampling_frequency for moment in time]
# get channel specific data
buffer = result[channel]
return buffer, time
=== 3.5.3 Reset the Logic Analyzer ===
After usage, reset the logic analyzer to the default settings.
def close(device_data):
"""
reset the instrument
"""
dwf.FDwfDigitalInReset(device_data.handle)
return
<--
--> 3.6 Pattern Generator #
=== 3.6.1 Generate Logic Signals ===
Configure the pattern generator to generate logic signals.
You can use a DIO line for pattern generation only if the respective line is configured as input and set to LOW state by the static I/O instrument (these are the default settings for all lines).
You can define custom function, trigger source and idle state names, to make the usage of the function easier.
class function:
""" function names """
pulse = constants.DwfDigitalOutTypePulse
custom = constants.DwfDigitalOutTypeCustom
random = constants.DwfDigitalOutTypeRandom
class trigger_source:
""" trigger source names """
none = constants.trigsrcNone
analog = constants.trigsrcDetectorAnalogIn
digital = constants.trigsrcDetectorDigitalIn
external = [None, constants.trigsrcExternal1, constants.trigsrcExternal2, constants.trigsrcExternal3, constants.trigsrcExternal4]
class idle_state:
""" channel idle states """
initial = constants.DwfDigitalOutIdleInit
high = constants.DwfDigitalOutIdleHigh
low = constants.DwfDigitalOutIdleLow
high_impedance = constants.DwfDigitalOutIdleZet
def generate(device_data, channel, function, frequency, duty_cycle=50, data=[], wait=0, repeat=0, run_time=0, idle=idle_state.initial, trigger_enabled=False, trigger_source=trigger_source.none, trigger_edge_rising=True):
"""
generate a logic signal
parameters: - channel - the selected DIO line number
- function - possible: pulse, custom, random
- frequency in Hz
- duty cycle in percentage, used only if function = pulse, default is 50%
- data list, used only if function = custom, default is empty
- wait time in seconds, default is 0 seconds
- repeat count, default is infinite (0)
- run_time: in seconds, 0=infinite, "auto"=auto
- idle - possible: initial, high, low, high_impedance, default = initial
- trigger_enabled - include/exclude trigger from repeat cycle
- trigger_source - possible: none, analog, digital, external[1-4]
- trigger_edge_rising - True means rising, False means falling, None means either, default is rising
"""
# get internal clock frequency
internal_frequency = ctypes.c_double()
dwf.FDwfDigitalOutInternalClockInfo(device_data.handle, ctypes.byref(internal_frequency))
# get counter value range
counter_limit = ctypes.c_uint()
dwf.FDwfDigitalOutCounterInfo(device_data.handle, ctypes.c_int(channel), ctypes.c_int(0), ctypes.byref(counter_limit))
# calculate the divider for the given signal frequency
if function == constants.DwfDigitalOutTypePulse:
divider = int(-(-(internal_frequency.value / frequency) // counter_limit.value))
else:
divider = int(internal_frequency.value / frequency)
# enable the respective channel
dwf.FDwfDigitalOutEnableSet(device_data.handle, ctypes.c_int(channel), ctypes.c_int(1))
# set output type
dwf.FDwfDigitalOutTypeSet(device_data.handle, ctypes.c_int(channel), function)
# set frequency
dwf.FDwfDigitalOutDividerSet(device_data.handle, ctypes.c_int(channel), ctypes.c_int(divider))
# set idle state
dwf.FDwfDigitalOutIdleSet(device_data.handle, ctypes.c_int(channel), idle)
# set PWM signal duty cycle
if function == constants.DwfDigitalOutTypePulse:
# calculate counter steps to get the required frequency
steps = int(round(internal_frequency.value / frequency / divider))
# calculate steps for low and high parts of the period
high_steps = int(steps * duty_cycle / 100)
low_steps = int(steps - high_steps)
dwf.FDwfDigitalOutCounterSet(device_data.handle, ctypes.c_int(channel), ctypes.c_int(low_steps), ctypes.c_int(high_steps))
# load custom signal data
elif function == constants.DwfDigitalOutTypeCustom:
# format data
buffer = (ctypes.c_ubyte * ((len(data) + 7) >> 3))(0)
for index in range(len(data)):
if data[index] != 0:
buffer[index >> 3] |= 1 << (index & 7)
# load data
dwf.FDwfDigitalOutDataSet(device_data.handle, ctypes.c_int(channel), ctypes.byref(buffer), ctypes.c_int(len(data)))
# calculate run length
if run_time == "auto":
run_time = len(data) / frequency
# set wait time
dwf.FDwfDigitalOutWaitSet(device_data.handle, ctypes.c_double(wait))
# set repeat count
dwf.FDwfDigitalOutRepeatSet(device_data.handle, ctypes.c_int(repeat))
# set run length
dwf.FDwfDigitalOutRunSet(device_data.handle, ctypes.c_double(run_time))
# enable triggering
dwf.FDwfDigitalOutRepeatTriggerSet(device_data.handle, ctypes.c_int(trigger_enabled))
if trigger_enabled:
# set trigger source
dwf.FDwfDigitalOutTriggerSourceSet(device_data.handle, trigger_source)
# set trigger slope
if trigger_edge_rising == True:
# rising edge
dwf.FDwfDigitalOutTriggerSlopeSet(device_data.handle, constants.DwfTriggerSlopeRise)
elif trigger_edge_rising == False:
# falling edge
dwf.FDwfDigitalOutTriggerSlopeSet(device_data.handle, constants.DwfTriggerSlopeFall)
elif trigger_edge_rising == None:
# either edge
dwf.FDwfDigitalOutTriggerSlopeSet(device_data.handle, constants.DwfTriggerSlopeEither)
# start generating the signal
dwf.FDwfDigitalOutConfigure(device_data.handle, ctypes.c_int(True))
return
=== 3.6.2 Reset the Pattern Generator ===
After usage, reset the pattern generator to the default settings.
def close(device_data):
"""
reset the instrument
"""
dwf.FDwfDigitalOutReset(device_data.handle)
return
<--
--> 3.7 Static I/O #
=== 3.7.1 Set Pins As Input Or As Output ===
Each digital pin of the Test & Measurement device can be used only as input, or as output at a time. The default settings for each line are input states.
def set_mode(device_data, channel, output):
"""
set a DIO line as input, or as output
parameters: - device data
- selected DIO channel number
- True means output, False means input
"""
# load current state of the output enable buffer
mask = ctypes.c_uint16()
dwf.FDwfDigitalIOOutputEnableGet(device_data.handle, ctypes.byref(mask))
# convert mask to list
mask = list(bin(mask.value)[2:].zfill(16))
# set bit in mask
if output:
mask[15 - channel] = "1"
else:
mask[15 - channel] = "0"
# convert mask to number
mask = "".join(element for element in mask)
mask = int(mask, 2)
# set the pin to output
dwf.FDwfDigitalIOOutputEnableSet(device_data.handle, ctypes.c_int(mask))
return
=== 3.7.2 Get Pin State ===
Read the state of a DIO line with the following code snippet:
def get_state(device_data, channel):
"""
get the state of a DIO line
parameters: - device data
- selected DIO channel number
returns: - True if the channel is HIGH, or False, if the channel is LOW
"""
# load internal buffer with current state of the pins
dwf.FDwfDigitalIOStatus(device_data.handle)
# get the current state of the pins
data = ctypes.c_uint32() # variable for this current state
dwf.FDwfDigitalIOInputStatus(device_data.handle, ctypes.byref(data))
# convert the state to a 16 character binary string
data = list(bin(data.value)[2:].zfill(16))
# check the required bit
if data[15 - channel] != "0":
value = True
else:
value = False
return value
=== 3.7.3 Set Pin State ===
To set the state of a DIO line, it must be set as output!
def set_state(device_data, channel, value):
"""
set a DIO line as input, or as output
parameters: - device data
- selected DIO channel number
- True means HIGH, False means LOW
"""
# load current state of the output state buffer
mask = ctypes.c_uint16()
dwf.FDwfDigitalIOOutputGet(device_data.handle, ctypes.byref(mask))
# convert mask to list
mask = list(bin(mask.value)[2:].zfill(16))
# set bit in mask
if value:
mask[15 - channel] = "1"
else:
mask[15 - channel] = "0"
# convert mask to number
mask = "".join(element for element in mask)
mask = int(mask, 2)
# set the pin state
dwf.FDwfDigitalIOOutputSet(device_data.handle, ctypes.c_int(mask))
return
=== 3.7.4 Reset the Static I/O ===
After usage, reset the instrument to the default settings.
def close(device_data):
"""
reset the instrument
"""
dwf.FDwfDigitalIOReset(device_data.handle)
return
<--
--> 3.8 Protocol: UART #
=== 3.8.1 Initialize the Interface ===
Before using a communication interface, it must be initialized by setting the communication parameters to the desired values.
def open(device_data, rx, tx, baud_rate=9600, parity=None, data_bits=8, stop_bits=1):
"""
initializes UART communication
parameters: - device data
- rx (DIO line used to receive data)
- tx (DIO line used to send data)
- baud_rate (communication speed, default is 9600 bits/s)
- parity possible: None (default), True means even, False means odd
- data_bits (default is 8)
- stop_bits (default is 1)
"""
# set baud rate
dwf.FDwfDigitalUartRateSet(device_data.handle, ctypes.c_double(baud_rate))
# set communication channels
dwf.FDwfDigitalUartTxSet(device_data.handle, ctypes.c_int(tx))
dwf.FDwfDigitalUartRxSet(device_data.handle, ctypes.c_int(rx))
# set data bit count
dwf.FDwfDigitalUartBitsSet(device_data.handle, ctypes.c_int(data_bits))
# set parity bit requirements
if parity == True:
parity = 2
elif parity == False:
parity = 1
else:
parity = 0
dwf.FDwfDigitalUartParitySet(device_data.handle, ctypes.c_int(parity))
# set stop bit count
dwf.FDwfDigitalUartStopSet(device_data.handle, ctypes.c_double(stop_bits))
# initialize channels with idle levels
# dummy read
dummy_buffer = ctypes.create_string_buffer(0)
dummy_buffer = ctypes.c_int(0)
dummy_parity_flag = ctypes.c_int(0)
dwf.FDwfDigitalUartRx(device_data.handle, dummy_buffer, ctypes.c_int(0), ctypes.byref(dummy_buffer), ctypes.byref(dummy_parity_flag))
# dummy write
dwf.FDwfDigitalUartTx(device_data.handle, dummy_buffer, ctypes.c_int(0))
return
=== 3.8.2 Receive Data ===
Use the function to the right to read data on an initialized UART interface.
def read(device_data):
"""
receives data from UART
parameters: - device data
return: - integer list containing the received bytes
- error message or empty string
"""
# variable to store results
error = ""
rx_data = []
# create empty string buffer
data = (ctypes.c_ubyte * 8193)()
# character counter
count = ctypes.c_int(0)
# parity flag
parity_flag= ctypes.c_int(0)
# read up to 8k characters
dwf.FDwfDigitalUartRx(device_data.handle, data, ctypes.c_int(ctypes.sizeof(data)-1), ctypes.byref(count), ctypes.byref(parity_flag))
# append current data chunks
for index in range(0, count.value):
rx_data.append(int(data[index]))
# ensure data integrity
while count.value > 0:
# create empty string buffer
data = (ctypes.c_ubyte * 8193)()
# character counter
count = ctypes.c_int(0)
# parity flag
parity_flag= ctypes.c_int(0)
# read up to 8k characters
dwf.FDwfDigitalUartRx(device_data.handle, data, ctypes.c_int(ctypes.sizeof(data)-1), ctypes.byref(count), ctypes.byref(parity_flag))
# append current data chunks
for index in range(0, count.value):
rx_data.append(int(data[index]))
# check for not acknowledged
if error == "":
if parity_flag.value < 0:
error = "Buffer overflow"
elif parity_flag.value > 0:
error = "Parity error: index {}".format(parity_flag.value)
return rx_data,
=== 3.8.3 Send Data ===
Use the function to the right to send data on an initialized UART interface to another device.
def write(device_data, data):
"""
send data through UART
parameters: - data of type string, int, or list of characters/integers
"""
# cast data
if type(data) == int:
data = "".join(chr (data))
elif type(data) == list:
data = "".join(chr (element) for element in data)
# encode the string into a string buffer
data = ctypes.create_string_buffer(data.encode("UTF-8"))
# send text, trim zero ending
dwf.FDwfDigitalUartTx(device_data.handle, data, ctypes.c_int(ctypes.sizeof(data)-1))
return
=== 3.8.4 Reset the Interface ===
After usage, reset the instrument to the default settings.
def close(device_data):
"""
reset the uart interface
"""
dwf.FDwfDigitalUartReset(device_data.handle)
return
<--
--> 3.9 Protocol: SPI #
=== 3.9.1 Initialize the Interface ===
Before using a communication interface, it must be initialized by setting the communication parameters to the desired values.
def open(device_data, cs, sck, miso=None, mosi=None, clk_frequency=1e06, mode=0, order=True):
"""
initializes SPI communication
parameters: - device data
- cs (DIO line used for chip select)
- sck (DIO line used for serial clock)
- miso (DIO line used for master in - slave out, optional)
- mosi (DIO line used for master out - slave in, optional)
- frequency (communication frequency in Hz, default is 1MHz)
- mode (SPI mode: 0: CPOL=0, CPHA=0; 1: CPOL-0, CPHA=1; 2: CPOL=1, CPHA=0; 3: CPOL=1, CPHA=1)
- order (endianness, True means MSB first - default, False means LSB first)
"""
# set the clock frequency
dwf.FDwfDigitalSpiFrequencySet(device_data.handle, ctypes.c_double(clk_frequency))
# set the clock pin
dwf.FDwfDigitalSpiClockSet(device_data.handle, ctypes.c_int(sck))
if mosi != None:
# set the mosi pin
dwf.FDwfDigitalSpiDataSet(device_data.handle, ctypes.c_int(0), ctypes.c_int(mosi))
# set the initial state
dwf.FDwfDigitalSpiIdleSet(device_data.handle, ctypes.c_int(0), constants.DwfDigitalOutIdleZet)
if miso != None:
# set the miso pin
dwf.FDwfDigitalSpiDataSet(device_data.handle, ctypes.c_int(1), ctypes.c_int(miso))
# set the initial state
dwf.FDwfDigitalSpiIdleSet(device_data.handle, ctypes.c_int(1), constants.DwfDigitalOutIdleZet)
# set the SPI mode
dwf.FDwfDigitalSpiModeSet(device_data.handle, ctypes.c_int(mode))
# set endianness
if order:
# MSB first
dwf.FDwfDigitalSpiOrderSet(device_data.handle, ctypes.c_int(1))
else:
# LSB first
dwf.FDwfDigitalSpiOrderSet(device_data.handle, ctypes.c_int(0))
# set the cs pin HIGH
dwf.FDwfDigitalSpiSelect(device_data.handle, ctypes.c_int(cs), ctypes.c_int(1))
# dummy write
dwf.FDwfDigitalSpiWriteOne(device_data.handle, ctypes.c_int(1), ctypes.c_int(0), ctypes.c_int(0))
return
=== 3.9.2 Receive Data ===
Use the function to the right to read data on an initialized SPI interface.
def read(device_data, count, cs):
"""
receives data from SPI
parameters: - device data
- count (number of bytes to receive)
- chip select line number
return: - integer list containing the received bytes
"""
# enable the chip select line
dwf.FDwfDigitalSpiSelect(device_data.handle, ctypes.c_int(cs), ctypes.c_int(0))
# create buffer to store data
buffer = (ctypes.c_ubyte*count)()
# read array of 8 bit elements
dwf.FDwfDigitalSpiRead(device_data.handle, ctypes.c_int(1), ctypes.c_int(8), buffer, ctypes.c_int(len(buffer)))
# disable the chip select line
dwf.FDwfDigitalSpiSelect(device_data.handle, ctypes.c_int(cs), ctypes.c_int(1))
# decode data
data = [int(element) for element in buffer]
return data
=== 3.9.3 Send Data ===
Use the function to the right to send data on an initialized SPI interface to another device.
def write(device_data, data, cs):
"""
send data through SPI
parameters: - device data
- data of type string, int, or list of characters/integers
- chip select line number
"""
# cast data
if type(data) == int:
data = "".join(chr (data))
elif type(data) == list:
data = "".join(chr (element) for element in data)
# enable the chip select line
dwf.FDwfDigitalSpiSelect(device_data.handle, ctypes.c_int(cs), ctypes.c_int(0))
# create buffer to write
data = bytes(data, "utf-8")
buffer = (ctypes.c_ubyte * len(data))()
for index in range(0, len(buffer)):
buffer[index] = ctypes.c_ubyte(data[index])
# write array of 8 bit elements
dwf.FDwfDigitalSpiWrite(device_data.handle, ctypes.c_int(1), ctypes.c_int(8), buffer, ctypes.c_int(len(buffer)))
# disable the chip select line
dwf.FDwfDigitalSpiSelect(device_data.handle, ctypes.c_int(cs), ctypes.c_int(1))
return
=== 3.9.4 Reset the Interface ===
After usage, reset the instrument to the default settings.
def close(device_data):
"""
reset the spi interface
"""
dwf.FDwfDigitalSpiReset(device_data.handle)
return
<--
--> 3.10 Protocol: I2C #
=== 3.10.1 Initialize the Interface ===
Before using a communication interface, it must be initialized by setting the communication parameters to the desired values.
def open(device_data, sda, scl, clk_rate=100e03, stretching=True):
"""
initializes I2C communication
parameters: - device data
- sda (DIO line used for data)
- scl (DIO line used for clock)
- rate (clock frequency in Hz, default is 100KHz)
- stretching (enables/disables clock stretching)
returns: - error message or empty string
"""
# reset the interface
dwf.FDwfDigitalI2cReset(device_data.handle)
# clock stretching
if stretching:
dwf.FDwfDigitalI2cStretchSet(device_data.handle, ctypes.c_int(1))
else:
dwf.FDwfDigitalI2cStretchSet(device_data.handle, ctypes.c_int(0))
# set clock frequency
dwf.FDwfDigitalI2cRateSet(device_data.handle, ctypes.c_double(clk_rate))
# set communication lines
dwf.FDwfDigitalI2cSclSet(device_data.handle, ctypes.c_int(scl))
dwf.FDwfDigitalI2cSdaSet(device_data.handle, ctypes.c_int(sda))
# check bus
nak = ctypes.c_int()
dwf.FDwfDigitalI2cClear(device_data.handle, ctypes.byref(nak))
if nak.value == 0:
return "Error: I2C bus lockup"
# write 0 bytes
dwf.FDwfDigitalI2cWrite(device_data.handle, ctypes.c_int(0), ctypes.c_int(0), ctypes.c_int(0), ctypes.byref(nak))
if nak.value != 0:
return "NAK: index " + str(nak.value)
return ""
=== 3.10.2 Receive Data ===
Use the function to the right to read data on an initialized I2C interface.
def read(device_data, count, address):
"""
receives data from I2C
parameters: - device data
- count (number of bytes to receive)
- address (8-bit address of the slave device)
return: - integer list containing the received bytes
- error message or empty string
"""
# create buffer to store data
buffer = (ctypes.c_ubyte * count)()
# receive
nak = ctypes.c_int()
dwf.FDwfDigitalI2cRead(device_data.handle, ctypes.c_int(address << 1), buffer, ctypes.c_int(count), ctypes.byref(nak))
# decode data
data = [int(element) for element in buffer]
# check for not acknowledged
if nak.value != 0:
return data, "NAK: index " + str(nak.value)
return data, ""
=== 3.10.3 Send Data ===
Use the function to the right to send data on an initialized I2C interface to another device.
def write(device_data, data, address):
"""
send data through I2C
parameters: - device data
- data of type string, int, or list of characters/integers
- address (8-bit address of the slave device)
returns: - error message or empty string
"""
# cast data
if type(data) == int:
data = "".join(chr (data))
elif type(data) == list:
data = "".join(chr (element) for element in data)
# encode the string into a string buffer
data = bytes(data, "utf-8")
buffer = (ctypes.c_ubyte * len(data))()
for index in range(0, len(buffer)):
buffer[index] = ctypes.c_ubyte(data[index])
# send
nak = ctypes.c_int()
dwf.FDwfDigitalI2cWrite(device_data.handle, ctypes.c_int(address << 1), buffer, ctypes.c_int(ctypes.sizeof(buffer)), ctypes.byref(nak))
# check for not acknowledged
if nak.value != 0:
return "NAK: index " + str(nak.value)
return ""
=== 3.10.4 Reset the Interface ===
After usage, reset the instrument to the default settings.
def close(device_data):
"""
reset the i2c interface
"""
dwf.FDwfDigitalI2cReset(device_data.handle)
return
<--
----
==== 4. Disconnecting the Device ====
When your script is exiting, it is very important to close the opened connections, to make the device available for other software (like the WaveForms application).
def close(device_data):
"""
close a specific device
"""
dwf.FDwfDeviceClose(device_data.handle)
return
----
===== Creating Modules =====
To avoid copying several hundred lines of code into every project, you can create Python modules from the functions controlling the instruments. These modules then can be imported in your project.
To create a module, create a new file with the desired name and the extension ***.py**, then copy the respective functions into that file. Don't forget to also import the dwfconstants file into every module. Place your modules in a separate folder, name this folder (for example WF_SDK is a good name as it is suggestive).
You can download the archive containing the module and some test files [[https://github.com/Digilent/WaveForms-SDK-Getting-Started-PY/archive/refs/heads/master.zip|here]].
As the created function set will be used as a module, an initializer is needed, to let the editors recognize the module. This file contains only the description of the module and imports every file in the module, to make the functions accessible. The created file has to be named __init__.py and must be put in the module directory. After the file is created, your module will be recognized: the module name in the text editor will be colored (this depends on the editor) and if you hover the mouse on the module name, the module description appears.
"""
This module realizes communication with Digilent Test & Measurement devices
"""
from WF_SDK import device
from WF_SDK import scope
from WF_SDK import wavegen
from WF_SDK import supplies
from WF_SDK import dmm
from WF_SDK import logic
from WF_SDK import pattern
from WF_SDK import static
from WF_SDK import protocol
Remember, that any submodule (the protocol folder in this case) also needs initialization:
"""
This module controls the protocol instrument
"""
from WF_SDK.protocol import i2c
from WF_SDK.protocol import spi
from WF_SDK.protocol import uart
----
==== Testing ====
Copy your module folder (WF_SDK in this case) into the project directory, then create a new Python script. Import the necessary modules, then use your functions to control the Test & Measurement device.
In the drop-downs below, several examples and a project template will be presented.
**Note: ** //The example using the oscilloscope and the waveform generator won't work on devices without analog I/O capability (Digital Discovery).//
**Note: ** //Name your test scripts "test_testname.py". This will be important if you want to install the module as a package.//
--> Empty Project Template #
Fill in this template. Be creative, use any instrument in any configuration.
from WF_SDK import device # import instruments
"""-----------------------------------------------------------------------"""
# connect to the device
device_data = device.open()
"""-----------------------------------"""
# use instruments here
"""-----------------------------------"""
# close the connection
device.close(device_data)
<--
--> Using the Oscilloscope and the Waveform Generator #
This example generates a sinusoidal signal on a wavegen channel, then records it on a scope channel. Connect the respective channels together on your device!
{{ :test-and-measurement:analog-discovery-3:ad3-scope-wavegen-bb.png?400 |}}
{{ :test-and-measurement:guides:scope-wavegen.png?600 |}}
from WF_SDK import device, scope, wavegen # import instruments
import matplotlib.pyplot as plt # needed for plotting
"""-----------------------------------------------------------------------"""
# connect to the device
device_data = device.open()
"""-----------------------------------"""
# initialize the scope with default settings
scope.open(device_data)
# generate a 10KHz sine signal with 2V amplitude on channel 1
wavegen.generate(device_data, channel=1, function=wavegen.function.sine, offset=0, frequency=10e03, amplitude=2)
# record data with the scopeon channel 1
buffer, time = scope.record(device_data, channel=1)
# plot
time = [moment * 1e03 for moment in time] # convert time to ms
plt.plot(time, buffer)
plt.xlabel("time [ms]")
plt.ylabel("voltage [V]")
plt.show()
# reset the scope
scope.close(device_data)
# reset the wavegen
wavegen.close(device_data)
"""-----------------------------------"""
# close the connection
device.close(device_data)
<--
--> Using the Logic Analyzer and the Pattern Generator #
This example generates a PWM signal on a DIO line and reads it back with the logic analyzer. As the same line is used both as input and as output, no external connections have to be made.
{{ :test-and-measurement:guides:logic-pattern.png?600 |}}
from WF_SDK import device, logic, pattern # import instruments
import matplotlib.pyplot as plt # needed for plotting
"""-----------------------------------------------------------------------"""
# connect to the device
device_data = device.open()
"""-----------------------------------"""
# initialize the logic analyzer with default settings
logic.open(device_data)
# generate a 100KHz PWM signal with 30% duty cycle on DIO0
pattern.generate(device_data, channel=0, function=pattern.function.pulse, frequency=100e03, duty_cycle=30)
# record a logic signal on DIO0
buffer, time = logic.record(device_data, channel=0)
# plot
time = [moment * 1e06 for moment in time] # convert time to μs
plt.plot(time, buffer)
plt.xlabel("time [μs]")
plt.ylabel("logic value")
plt.yticks([0, 1])
plt.show()
# reset the logic analyzer
logic.close(device_data)
# reset the pattern generator
pattern.close(device_data)
"""-----------------------------------"""
# close the connection
device.close(device_data)
<--
--> Using the Static I/O and the Power Supplies #
Connect LEDs and series resistors to each DIO channel of your device. Use the positive, or the digital power supply to provide current to the LEDs, then use the Static I/O instrument to sink the currents (turn the LEDs on/off).
{{ :test-and-measurement:analog-discovery-3:ad3-static-io-supplies-bb.png?600 |}}
from WF_SDK import device, static, supplies # import instruments
from time import sleep # needed for delays
device_name = "Analog Discovery 3"
"""-----------------------------------------------------------------------"""
# connect to the device
device_data = device.open()
device_data.name = device_name
"""-----------------------------------"""
# start the positive supply
supplies_data = supplies.data()
supplies_data.master_state = True
supplies_data.state = True
supplies_data.voltage = 3.3
supplies.switch(device_data, supplies_data)
# set all pins as output
for index in range(16):
static.set_mode(device_data, index, True)
try:
while True:
# repeat
mask = 1
while mask < 0x10000:
# go through possible states
for index in range(16):
# set the state of every DIO channel
static.set_state(device_data, index, not(mask & pow(2, index)))
sleep(0.1) # delay
mask <<= 1 # switch mask
while mask > 1:
# go through possible states backward
mask >>= 1 # switch mask
for index in range(16):
# set the state of every DIO channel
static.set_state(device_data, index, not(mask & pow(2, index)))
sleep(0.1) # delay
except KeyboardInterrupt:
# stop if Ctrl+C is pressed
pass
finally:
# stop the static I/O
static.close(device_data)
# stop and reset the power supplies
supplies_data.master_state = False
supplies.switch(device_data, supplies_data)
supplies.close(device_data)
"""-----------------------------------"""
# close the connection
device.close(device_data)
<--
--> Controlling the Pmod CLS and the Pmod MAXSonar with UART #
Connect the UART interface of both Pmods to your Test & Measurement device as presented below. Pay special attention to the jumpers on the Pmod CLS. Use the positive, or the digital power supply to provide current to the Pmods, then receive and send data with the protocol instrument.
{{ :test-and-measurement:analog-discovery-3:ad3-pmodcls-maxsonar.png?600 |}}
from WF_SDK import device, supplies, static # import instruments
from WF_SDK.protocol import uart # import protocol instrument
from time import sleep # needed for delays
device_name = "Analog Discovery 3"
"""-----------------------------------------------------------------------"""
# connect to the device
device_data = device.open()
device_data.name = device_name
"""-----------------------------------"""
# define MAXSonar reset line
reset = 2
# define timeout iteration count
timeout = 1000
# start the power supplies
supplies_data = supplies.data()
supplies_data.master_state = True
supplies_data.state = True
supplies_data.voltage = 3.3
supplies.switch(device_data, supplies_data)
sleep(0.1) # delay
# initialize the reset line
static.set_mode(device_data, reset, output=True)
static.set_state(device_data, reset, False)
# initialize the uart interface on DIO0 and DIO1
uart.open(device_data, tx=0, rx=1, baud_rate=9600)
try:
# repeat
while True:
# clear the screen and home cursor
uart.write(device_data, "\x1b[j")
# display a message
uart.write(device_data, "Dist: ")
# read raw data
static.set_state(device_data, reset, True) # enable the device
message = ""
for _ in range(timeout):
# wait for data
message, error = uart.read(device_data)
if message != "":
# exit when data is received
break
static.set_state(device_data, reset, False) # disable the device
# convert raw data into distance
try:
if message[0] == 234:
message.pop(0) # remove first byte
value = 0
for element in message:
if element > 47 and element < 58:
# concatenate valid bytes
value = value * 10 + (element - 48)
value *= 2.54 # convert to cm
except:
# error in message
value = -1
# display the distance
uart.write(device_data, str(round(value, 2)))
# display a message
uart.write(device_data, "cm")
# delay 1s
sleep(1)
except KeyboardInterrupt:
# exit on Ctrl+C
pass
# reset the interface
uart.close(device_data)
# reset the static I/O
static.set_mode(device_data, reset, output=False)
static.set_state(device_data, reset, True)
static.close(device_data)
# stop and reset the power supplies
supplies_data.master_state = False
supplies.switch(device_data, supplies_data)
supplies.close(device_data)
"""-----------------------------------"""
# close the connection
device.close(device_data)
<--
--> Controlling the Pmod CLS and the Pmod ALS with SPI #
Connect the SPI interface of both Pmods to your Test & Measurement device as presented below. Pay special attention to the jumpers on the Pmod CLS. Use the positive, or the digital power supply to provide current to the Pmods, then receive and send data with the protocol instrument.
{{ :test-and-measurement:analog-discovery-3:ad3-pmodcls-pmodals.png?600 |}}
from WF_SDK import device, supplies # import instruments
from WF_SDK.protocol import spi # import protocol instrument
from time import sleep # needed for delays
device_name = "Analog Discovery 3"
"""-----------------------------------------------------------------------"""
# connect to the device
device_data = device.open()
device_data.name = device_name
"""-----------------------------------"""
# define chip select lines
CLS_cs = 0
ALS_cs = 1
# start the power supplies
supplies_data = supplies.data()
supplies_data.master_state = True
supplies_data.state = True
supplies_data.voltage = 3.3
supplies.switch(device_data, supplies_data)
# initialize the spi interface on DIO0, DIO1, DIO2, DIO3 and DIO4
spi.open(device_data, CLS_cs, sck=2, miso=3, mosi=4)
spi.open(device_data, ALS_cs, sck=2, miso=3, mosi=4)
try:
# repeat
while True:
# clear the screen and home cursor
spi.write(device_data, "\x1b[j", CLS_cs)
# display a message
spi.write(device_data, "Lum: ", CLS_cs)
# read the temperature
message = spi.read(device_data, 2, ALS_cs)
value = ((int(message[0]) << 3) | (int(message[1]) >> 4)) / 1.27
# display the temperature
spi.write(device_data, str(round(value, 2)), CLS_cs)
# display a message
spi.write(device_data, "%", CLS_cs)
# delay 1s
sleep(1)
except KeyboardInterrupt:
# exit on Ctrl+C
pass
# reset the interface
spi.close(device_data)
# stop and reset the power supplies
supplies_data.master_state = False
supplies.switch(device_data, supplies_data)
supplies.close(device_data)
"""-----------------------------------"""
# close the connection
device.close(device_data)
<--
--> Controlling the Pmod CLS and the Pmod TMP2 with I2C #
Connect the I2C interface of both Pmods to your Test & Measurement device as presented below. Pay special attention to the jumpers on the Pmod CLS. Use the positive, or the digital power supply to provide current to the Pmods, then receive and send data with the protocol instrument.
{{ :test-and-measurement:analog-discovery-3:ad3-pmodcls-pmodtmp2.png?600 |}}
from WF_SDK import device, supplies # import instruments
from WF_SDK.protocol import i2c # import protocol instrument
from time import sleep # needed for delays
device_name = "Analog Discovery 3"
"""-----------------------------------------------------------------------"""
# connect to the device
device_data = device.open()
device_data.name = device_name
"""-----------------------------------"""
# define i2c addresses
CLS_address = 0x48
TMP2_address = 0x4B
# start the power supplies
supplies_data = supplies.data()
supplies_data.master_state = True
supplies_data.state = True
supplies_data.voltage = 3.3
supplies.switch(device_data, supplies_data)
sleep(0.1) # delay
# initialize the i2c interface on DIO0 and DIO1
i2c.open(device_data, sda=0, scl=1)
# initialize the PMOD TMP2 (set output size to 16-bit)
i2c.write(device_data, [0x03, 0x80], TMP2_address)
# save custom character
i2c.write(device_data, "\x1b[7;5;7;0;0;0;0;0;0d", CLS_address) # define character
i2c.write(device_data, "\x1b[3p", CLS_address) # load character table
try:
# repeat
while True:
# clear the screen and home cursor
i2c.write(device_data, [0x1B, 0x5B, 0x6A], CLS_address)
# display a message
i2c.write(device_data, "Temp: ", CLS_address)
# read the temperature
message, error = i2c.read(device_data, 2, TMP2_address) # read 2 bytes
value = (int(message[0]) << 8) | int(message[1]) # create integer from received bytes
if ((value >> 15) & 1) == 0:
value /= 128 # decode positive numbers
else:
value = (value - 65535) / 128 # decode negative numbers
# display the temperature
i2c.write(device_data, str(round(value, 2)), CLS_address)
# display a message
i2c.write(device_data, 0, CLS_address)
i2c.write(device_data, "C", CLS_address)
# delay 1s
sleep(1)
except KeyboardInterrupt:
# exit on Ctrl+C
pass
# reset the interface
i2c.close(device_data)
# stop and reset the power supplies
supplies_data.master_state = False
supplies.switch(device_data, supplies_data)
supplies.close(device_data)
"""-----------------------------------"""
# close the connection
device.close(device_data)
<--
----
==== Installing the Package ====
Once you completed the package, you might want to install it, like other Python packages and use it on new projects as well. To do so, you must create some additional files in the project folder.
First, exclude the test scripts from the final package. Create a file named **MANIFEST.in**, with the content:
global-exclude test_*
The installer needs the list of dependencies to install your package. Specify this list on a file called **requirements.txt**:
setuptools==58.1.0
wheel==0.37.1
Finally, create a **README.md** file with the description of your package, then create the installer. The installer is the file named **setup.py**, with the following content:
from setuptools import setup
with open("README.md", "r") as f:
long_description = f.read()
setup(
name = "WF_SDK",
version = "1.0",
description = "This module realizes communication with Digilent Test & Measurement devices",
license = "MIT",
long_description = long_description,
author = "author_name",
author_email = "author_email_address",
url = "https://digilent.com/reference/test-and-measurement/guides/waveforms-sdk-getting-started",
packages = ["WF_SDK", "WF_SDK.protocol"],
)
Once the necessary files are created, open a terminal, go to the project folder and install your package with the following command:
pip3 install .
Alternatively, you can install the package from the GitHub repository, with the command:
pip3 install git+https://github.com/Digilent/WaveForms-SDK-Getting-Started-PY#egg=WF_SDK
If you already installed the package, you can update it with the command:
pip3 install --force-reinstall git+https://github.com/Digilent/WaveForms-SDK-Getting-Started-PY#egg=WF_SDK
**Note:** //Use "pip" instead of "pip3", if you are using Python 2.//
----
===== Other Programming Languages =====
Realizing the same package in other programming languages is also possible. To check the C++ version of the package and some test programs, follow this [[https://github.com/Digilent/WaveForms-SDK-Getting-Started-Cpp|GitHub repository, C++]] link.
----
===== Next Steps =====
For more guides on how to use your Digilent Test & Measurement Device, return to the device's Resource Center, linked from the [[test-and-measurement:start]] page of this wiki.
For more information on the WaveForms SDK visit the [[software:waveforms:waveforms-sdk:start|WaveForms SDK Resource Center]].
For more information on WaveForms visit the [[software:waveforms:waveforms-3:reference-manual|]].
For technical support, please visit the [[https://forum.digilent.com/forum/8-test-and-measurement/|Test and Measurement]] section of the Digilent Forums.