Electronics Testbench Automation Library
(C) 2023 Pat Deegan, psychogenic.com
This Python library is a set of utilities and wrappers (mostly built-atop the awesome easy_scpi) to allow for simplified control of lab instruments.
It is a repository of interfaces for the electronics lab instruments used here, and by much of the maker community and other companies.
Its goal is to offer a sensibly uniform means of controlling and querying power supplies, oscilloscopes, multimeters, signal generators and other tools used in a electronics lab.
- Siglent SPD3303x power supplies
- Rigol DS1000Z/MSO1000Z series oscilloscopes (like the classic DS1054z)
- Unitrend Uni-T UTG9xx signal generators (tested on the UTG962)
- Unitrend Uni-T UT880x multi-meters (test on UT8804N, should work on all 8000 series?)
If you use something else and would like to have it supported in the library, you can use existing code for inspiration or get in touch with me with questions or for consulting.
It's a pure Python library, installation is pretty standard (and optional)
Just clone the repo and you should be able to run the examples from the directory which contains the psytestbench package, e.g.
python3 psytestbench/examples/console.py
(note, you'll want to edit psytestbench/examples/mylab.py to set the instrument IDs, see HOWTO below)
You can get the latest release .whl file, e.g. psytestbench-1.0.4-py3-none-any.whl
Install the requirements
$ pip3 install -r https://raw.githubusercontent.com/psychogenic/psytestbench/main/requirements.txt
Install the package
$ pip3 install ./psytestbench-*-py3-none-any.whl
From the top level dir, you can build packages and install the usual way, e.g. with
$ pip3 install -r ./requirements.txt
$ python3 -m build
$ pip3 install ./dist/psytestbench-*-py3-none-any.whl
A bit of interaction with the signal gen and scope
# instantiate
siggen = psytestbench.utg9xx.instrument.Instrument('USB0::26191::2100::3573542343::0::INSTR')
dso = psytestbench.ds1000z.instrument.Instrument('USB0::ETC::INSTR' )
siggen.connect()
dso.connect()
# set a 2khz square wave on 1
siggen.channel1.frequency(2000)
siggen.channel1.wave.square()
siggen.channel1.on()
# setup and turn on channels
dso.channel1.bandwidthLimit20MHz()
dso.channel1.couplingDC()
dso.channel1.on()
dso.channel2.couplingAC()
dso.channel2.on()
# set the trigger mode, looking at low freqs here
dso.trigger.modeEdge()
dso.trigger.edge.source(dso.channel1)
dso.trigger.couplingLowpass()
dso.trigger.normal()
# I want these to be monitored/measured
# freq on 1 and V peak-to-peak on 1 and 2
dso.measure.frequency(dso.channel1)
dso.measure.vPP(dso.channel1)
dso.measure.vPP(dso.channel2)
# make certain we're acquiring
dso.run()
freq = dso.measurement.frequency(dso.channel1)
vpp = dso.measurement.vPP(dso.channel1)
postvpp = dso.measurement.vPP(dso.channel2)
# ...
Each instrument may be used stand-alone but the most convenient method is to setup a collection of lab instruments and just access that from whichever script, console or REPL you're working on.
If your focus is on one particular instrument, I've created top-level READMEs in each of the package directories.
For the instrument collection, if you look into the psytestbench/examples/mylab.py you will see how I set up the LabInstruments
object to work in the examples and... my lab.
In short, you can describe the instruments you actually have, by selecting their type and defining how to access the resource.
All the instruments in this library are of various Instrument classes, so you import them all, e.g.
from psytestbench.ds1000z.instrument import Instrument as OScope
from psytestbench.spd3303x.instrument import Instrument as BenchSupply
# etc
and may then construct a LabInstruments object like so:
Lab = LabInstruments([
# TCP/IP connected DS1054z using SCPI
(OScope, 'TCPIP::192.168.0.24::INSTR'),
# USB connected psu and signal gen also using SCPI
(BenchSupply, 'USB0::1155::30016::SPD3EGFQ6R2092::0::INSTR' ),
(SigGen, 'USB0::26198::2100::3568543393::0::INSTR'),
# Uni-T DMM using it's own thing, through USB
(Multimeter, 'usb:10c4:ea80')
],
autoconnect=True)
Things to note:
- the LabInstruments takes a list of tuples, where each tuple is a (type, resourceId)
- the resourceId will of course be different for your instruments
- most of the IDs are SCPI identifiers, the multimeter here is a special case (it's a CP2110 USB interface)
From there, the LabInstruments object above will have accessors for any of the instrument types defined:
- oscilloscope or dso (e.g. lab.dso);
- signalGenerator;
- powerSupply or psu; and
- multimeter or dmm are currently available.
These are lazy-initialized, so you won't waste any time connecting to devices that you're not using.
So, how do you find the identifier for your instruments?
For SCPI instruments, it might be as simple as running a python shell and doing
>>> # import any of the SCPI instruments, say
>>> import psytestbench.ds1000z.instrument
>>>
>>> # call the listResources() class method on the Instrument class within
>>> psytestbench.ds1000z.instrument.Instrument.listResources()
('USB0::26198::2100::3568543393::0::INSTR',)
This will return a tuple of identifiers currently connected.
For non-scpi devices that may be accessed using the serial port, the identifier is either:
- the serial device, e.g. '/dev/ttyUSB0'
- the serial "URL", e.g. 'cp2110://1-2:1.0' (anything supported by serial.serial_for_url)
- the 'usb:' hack included here (the CP2110 device path changes depending on where you plug it in--annoying)
The usb hack is just a string with 'usb:VENDOR_ID:PRODUCT_ID' as shown by lsusb or whatever windows people use to find out the VID/PID of USB devices.
The examples directory has a few samples of the interfaces in use. Most interesting may be the filterscan.py which uses the signal generator and oscope to characterize a low frequency, low pass filter.
The signal gen sweeps frequencies using the siggen and measures input/output levels using the scope.
It has on-line --help
$ python psytestbench/examples/filterscan.py --help
usage: filterscan.py [-h] [--list] [--device DEVICE]
[--loglevel {debug,info,warn,error}] [--csv CSV]
[--freqmin FREQMIN] [--freqmax FREQMAX] [--step STEP]
[--numsamps NUMSAMPS] [--wave {sine,square,arb}]
[--amplitude AMPLITUDE] [--psu_program PSU_PROGRAM]
[--supply_voltage SUPPLY_VOLTAGE]
xfer function sweep (testbench v 1.0.0)
options:
-h, --help show this help message and exit
--list List all currently connected devices
--loglevel {debug,info,warn,error}
Set log level (verbosity)
--csv CSV CSV file to output [/tmp/sweep.csv]
--freqmin FREQMIN start frequency 50
--freqmax FREQMAX start frequency 1200
--step STEP start frequency 10
--numsamps NUMSAMPS Num samples to average [2]
--wave {sine,square,arb}
Select wave type [sine]
--amplitude AMPLITUDE
Select wave amplitude (Volts) [0.4]
--psu_program PSU_PROGRAM
PSU program to recall [1]
--supply_voltage SUPPLY_VOLTAGE
PSU supply voltage (Volts) [3.3]
The console allows manual control of instruments defined in the lab.
Here's a small session controlling the power supply
$ python psytestbench/examples/console.py
********* Psychogenic Testbench Console *********
Control instruments manually
* Lab instruments available *
Power: lab.powerSupply or lab.psu
Sig gen: lab.signalGenerator
o-scope: lab.oscilloscope or lab.dso
3/4 instrument types enabled.
>>> lab.psu.recall(1)
>>> lab.psu.channel1.voltage()
3.3
>>> lab.psu.channel1.voltage(3.14)
>>> lab.psu.channel1.voltage()
3.14
>>> lab.psu.channel1.on()
>>> lab.psu.measurement.voltage(lab.psu.channel1)
3.14
- Add documentation.
- Clean up the giant mess of importing my UTHID project into this testbench.
- More tools.
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