Python library to automate testing & characterization of power managment features of IoT systems.
The library makes use of PyVisa to automate the functionality of professional power supply / analysis equipment supporting the SCPI standard
The library could be used as a python module to create standalone scripts for learning and demonstration purposes. In addiition, it could be used professionally as pytest-plugin in a R&D environment to write automated test cases for a SUT (system under test).
The automation of power measurements was implemented based on the availablity of the two equipment listed below: These euipment are expensive to get. You can checkout my lower cost automation test setup as an alternative
You need to install the VISA drivers for the above equipment before you could communicate with them via PyVisa. The drivers are included as part of the following software components:
After installing the above on the host PC and connecting the equipment, you should be able to see them listed in Keysgiht Connection Expert software which means they should be identifiable by PyVisa.
Important Note: the current implementation of this library assumes the equipment are connected via USB interface
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Create a Python virtual environment using your Python3.x interpreter:
python3 -m venv venv # on Unix based OSpython -m venv venv # on Windows
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Activate the Python virtual environment
. venv/bin/activate # on Unix based OS
. venv/Scripts/activate # on Windows
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Install pypm-test as a module directly from the repository:
python3 -m pip install git+https://github.com/ammarkh95/pypm-test.git # on Unix based OSpython -m pip install git+https://github.com/ammarkh95/pypm-test.git # on Windows
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Usage as Python module with context managers
You can start utilizing pypm-test module directly in your scripts by importing the wrapper classes. However, to make the experience easier, I implemented context managers to confgiure the equipment output for measurement and control the setup / tear down of the equipment state between different contexts (e.g. switch off output voltage / current after exiting "with" block and reset default settings)
Keysight U3606 context manager example
import logging import time import pyvisa from pypm_test import KeysightU3606SupplyAndMultimeter, DCOutputMode, MultimeterMode pyvisa_dev_manager = pyvisa.ResourceManager() pyvisa.log_to_screen(logging.INFO) with KeysightU3606SupplyAndMultimeter(pyvisa_manager = pyvisa_dev_manager, serial_no = "XXXX", # add your equipment serial number here dc_output_mode = DCOutputMode.CONSTANT_VOLTAGE, # output voltage mulitimeter_mode = MultimeterMode.CURRENT, # measure current dc_output_value= 3.6) as psu: # Volts # enable output psu.enable_dc_output() # perform discrete measurements t_start = time.perf_counter() for _ in range(100): print(f"Multimeter [READ] Current Measuremet: {psu.read() * 1000:.3f} mA") t_end = time.perf_counter() print(f"Measurement Read via Keysight U3606 Multimeter took approx: {t_end - t_start:.3f} sec") # change DC output voltage psu.set_dc_supply_output_voltage(5.0) # fetch continuous measurments without a trigger psu.enable_continuous_mode() t_start = time.perf_counter() for _ in range(100): print(f"Multimeter [Fetch] Current Measuremet: {psu.fetch() * 1000:.3f} mA") t_end = time.perf_counter() print(f"Measurement Fetch via Keysight U3606 Multimeter took approx: {t_end - t_start:.3f} sec") # stop output psu.disable_dc_output()
Keysight U2723 context manager example
import logging import time import pyvisa from pypm_test import KeysightU2723SourceMeasureUnit, SMUChannelMode, SMUChannel pyvisa_dev_manager = pyvisa.ResourceManager() pyvisa.log_to_screen(logging.INFO) with KeysightU2723SourceMeasureUnit(pyvisa_manager = pyvisa_dev_manager, serial_no = "XXXX", # add your equipment serial number here smu_channel_1_output_mode = SMUChannelMode.SVMI, # Source Voltage Measure Current smu_channel_1_output_value = 3.6, # Volts smu_channel_2_output_mode = SMUChannelMode.SIMV, # Source Current Measure Voltage smu_channel_2_output_value = 0.01) as smu: # Amps # enable Voltage output on Channel 1 & Current output on Channel 2 smu.enable_smu_channel(SMUChannel.CH1) smu.enable_smu_channel(SMUChannel.CH2) # perform discrete voltage and current measurements t_start = time.perf_counter() for _ in range(100): print(f"CH1 (Voltage): {smu.measure_voltage_scalar(SMUChannel.CH1):.3f} V, CH1 (Current): {smu.measure_current_scalar(SMUChannel.CH1) * 1000:.3f} mA") print(f"CH2 (Voltage): {smu.measure_voltage_scalar(SMUChannel.CH2):.3f} V, CH2 (Current): {smu.measure_current_scalar(SMUChannel.CH2) * 1000:.3f} mA") t_end = time.perf_counter() print(f"Scalar measurements via Keysight U2723 SMU took approx: {t_end - t_start:.3f} sec") # configure sweep measurements (150 readings with 40 ms interval) smu.set_sweep_interval(SMUChannel.CH1, 40) smu.set_sweep_points(SMUChannel.CH1, 150) smu.set_sweep_interval(SMUChannel.CH2, 40) smu.set_sweep_points(SMUChannel.CH2, 150) # trigger array measurements t_start = time.perf_counter() current_data = smu.measure_current_array(SMUChannel.CH1) voltage_data = smu.measure_voltage_array(SMUChannel.CH2) print(f"CH1 (Current Data Points): {len(current_data)}, CH1 (Last Current Data Point): {current_data[-1] * 1000:.3f} mA") print(f"CH2 (Voltage Data Points): {len(voltage_data)}, CH2 (Last Voltage Data Point): {voltage_data[-1]:.3f} V") t_end = time.perf_counter() print(f"Array measurements via Keysight U2723 SMU took approx: {t_end - t_start:.3f} sec") # stop output on Channels 1 and 2 smu.disable_smu_channel(SMUChannel.CH1) smu.disable_smu_channel(SMUChannel.CH2)
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Usage as Pytest-plugin with pytest fixtures
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A number of fixtures are implemented to help setup predefined workflow(s) for the instrument at the begining / end of the test, do a measurement based on your test context and then do a teardown / reset of the instrument at the end of the test
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You can list available fixtures from pypm-test by running the command below. Also by looking at fixtures.py file:
pytest --fixtures
Keysight U3606 pytest test case example
########################################### # pytest.ini -> here provide fixtures configuration psu_serial_no = XXXXXXXXXX psu_multimeter_mode = current psu_constant_voltage_output = 3.60 # Volts psu_constant_current_output = 0.01 # Amps ########################################### # test_keysight_u3606_demo.py -> here write your test case from pypm_test import KeysightU3606Wrapper import logging def test_keysight_u3606_demo(psu_constant_voltage_output: KeysightU3606Wrapper) -> None: # perform immediate measurements for _ in range(10): I_val = psu_constant_voltage_output.read() logging.info(f"Current (I) value: {I_val * 1000:.3f} mA") # change DC output voltage psu_constant_voltage_output.set_dc_supply_output_voltage(4.2) # enable continuous measurments without a trigger psu_constant_voltage_output.enable_continuous_mode() # fetch measurements continuously for _ in range(10): I_val = psu_constant_voltage_output.fetch() logging.info(f"Current (I) value: {I_val * 1000:.3f} mA") # disable continuous mode psu_constant_voltage_output.disable_continuous_mode() ## add assertions in your test based on the context (e.g actual vs expected measurements) ...
Keysight U2723 pytest test case example
########################################### # pytest.ini -> here provide fixtures configuration # Source Measure Unit (SMU) Fixtures Options smu_serial_no = MY62460002 # Source Voltage Fixture Options smu_ch_1_source_voltage = 1.2 # Volts smu_ch_2_source_voltage = 1.8 smu_ch_3_source_voltage = 3.6 # Source Current Fixture Options smu_ch_1_source_current = 0.001 # Amps smu_ch_2_source_current = 0.01 smu_ch_3_source_current = 0.05 ########################################### # test_keysight_u2723_demo.py -> here write your test case from pypm_test import KeysightU2723Wrapper, SMUChannel import logging def test_keysight_u2723_demo(smu_voltage_source: KeysightU2723Wrapper) -> None: # perform scalar measurements for _ in range(10): logging.info(f"CH1 (Current): {smu_voltage_source.measure_current_scalar(SMUChannel.CH1) * 1000:.3f} mA") logging.info(f"CH2 (Current): {smu_voltage_source.measure_current_scalar(SMUChannel.CH2) * 1000:.3f} mA") logging.info(f"CH3 (Current): {smu_voltage_source.measure_current_scalar(SMUChannel.CH3) * 1000:.3f} mA") # change DC sourced voltages on three channels smu_voltage_source.set_smu_source_voltage(SMUChannel.CH1, 1.0) smu_voltage_source.set_smu_source_voltage(SMUChannel.CH2, 2.0) smu_voltage_source.set_smu_source_voltage(SMUChannel.CH3, 3.0) # perform array measurements: (100 points, 100 ms interval) smu_voltage_source.set_sweep_interval(SMUChannel.CH1, 100) smu_voltage_source.set_sweep_points(SMUChannel.CH1, 100) smu_voltage_source.set_sweep_interval(SMUChannel.CH2, 100) smu_voltage_source.set_sweep_points(SMUChannel.CH2, 100) smu_voltage_source.set_sweep_interval(SMUChannel.CH3, 100) smu_voltage_source.set_sweep_points(SMUChannel.CH3, 100) ch_1_data = smu_voltage_source.measure_current_array(SMUChannel.CH1) ch_2_data = smu_voltage_source.measure_current_array(SMUChannel.CH2) ch_3_data = smu_voltage_source.measure_current_array(SMUChannel.CH3) logging.info(f"CH1 (Current Data Points): {len(ch_1_data)}, CH1 (Last Current Data Point): {ch_1_data[-1] * 1000:.3f} mA") logging.info(f"CH2 (Current Data Points): {len(ch_2_data)}, CH2 (Last Current Data Point): {ch_2_data[-1] * 1000:.3f} mA") logging.info(f"CH3 (Current Data Points): {len(ch_3_data)}, CH3 (Last Current Data Point): {ch_3_data[-1] * 1000:.3f} mA") ## add assertions in your test based on the context (e.g actual vs expected measurements) ...
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Automated test cases are available inside the testing directory to verify majority of the functions of the library with the supported hardware. These could also serve as starting examples for writing your own test cases with regards to the system you are targeting in your test.
Contributions to pypm-test are welcome to extend the functions list / add wrappers for additonal test power equipment
Please reach out to me via E-mail: ammar.khallouf@tum.de to discuss your ideas