PST.. Program the Pico SCPI labTool?

6 Aug 2023

The Pico SCPI labTool (PST) allows you to connect your PC to equipment to control and monitor all sorts of things. It runs on a Raspberry Pico.
In this post: functionality, and how to use SCPI or LabVIEW to program the device.

Capabilities

Functions

control output pins	Set gpio outputs high or low (can drive a LED, relays, actuator, buzzer, ...)
get output pin status	query the current state of an output pin
get input pin status	query the state of an input pin (can be a digital signal, switch status, ...)	added in release 3
get analogue input	query the Pico ADC inputs, or the measurements from an attached ADS1115	added in release 2
set analogue output	Control a Pico pin's output value with variable duty cycle	added in release 3
get analogue output value	query the current set duty cycle of a Pico pin	added in release 3
digital input in: registers	instrument specific registers for digital input pins	added in release 4
service request	IEEE488.2 compliant service requests (e.g.: react on digital input status change)	added in release 5

Programming interface

control language	SCPI
connectivity	Universal Serial Bus Test and Measurement Class (USBTMC), VISA compatible
client software	LabVIEW Virtual Instrument driver (VI) direct SCPI control with pyVisa, MathLab, LabVIEW VISA compatible clients

Command reference

This section describes the supported (and not yet supported) commands. It lists

the SCPI syntax,
LabVIEW Virtual Instrument driver block
the pins that are used,
parameters, return values.

set digital output	drive digital output pin of PICO high or low	pins: 0: GP22 1: GP14 2: GP15
SCPI	DIGItal:OUTPut# <0\|1>	example: DIGI:OUTP0 1 #: pin parameter 1: boolean (0\|1 or OFF\|ON ) return: na
VI	Public/Action-Status/Digital Out Control	inputs: pin (int) state (bool) outputs: na

get digital output	query the state of a digital output	pins: 0: GP22 1: GP14 2: GP15
SCPI	DIGItal:OUTPut#?	example: DIGI:OUTP0? #: pin return: state (bool 0\|1)
VI	Public/Data/Read Digital Out	inputs: pin (int) outputs: state (bool 0\|1)

get digital input	query the state of a digital input	pins: 0: GP20 1: GP21 2: GP27
SCPI	DIGItal:INPut#?	example: DIGI:INP0? #: pin return: state (bool 0\|1)
VI	Public/Data/Read Digital In	inputs: pin (int) outputs: state (bool 0\|1)

get analogue input (standard)	query an ADC input of the Pico	pins: 0: GP26 (ADC0) 1: GP28 (ADC2)
SCPI	ANAlog:INPut#:RAW?	example: ANA:INP0:RAW? #: pin return: ADC value(integer 0-4095)
VI	Public/Data/Read Analog	inputs: pin (int) outputs: ADC value (integer 0-4095)

get analog input (high resolution)	query an input of attached ADS1115 ADC	pins: ADS1115 pin 0 - 3 developed by shabaz ! See the Extensions section below for hardware requirements.
SCPI	ANAlog:HIRES:INPut#:RAW?	#: pin return: ADC value(integer 0-32766)
VI	Public/Data/Read Analog HiRes	inputs: pin (int) outputs: ADC value (integer 0-32766)

set analog output	control pin of Pico with variable duty cicle	pins: 0: GP16 1: GP17 2: GP18 developed by shabaz
SCPI	ANAlog:OUTPut#:RAW <0-4095>	inputs: pin (int) Duty cycle value (integer 0-4095) outputs: na
VI	Public/Action-Status/Analog Out Control	inputs: pin (int) duty cycle (integer 0-4095) outputs: na

get analog output	query the set duty cycle set on a pin of Pico	pins: 0: GP16 1: GP17 2: GP18 developed by shabaz
SCPI	ANAlog:OUTPut#:RAW?	inputs: pin (int) outputs: Duty cycle value (integer 0-4095)
VI	Public/Data/Read Analog Out	inputs: pin (int) outputs: duty cycle (integer 0-4095)

init resource	initiate connection	VISA url: USB0::0xCAFE::0x4000::123456::INSTR
SCPI	na, connect via VISA API	client dependent
VI	Public/Initialize	inputs: VISA url outputs: na

close resource	release connection
SCPI	na, disconnect via VISA API	client dependent
VI	Public/Close	inputs: na outputs: na

Command reference: instrument specific registers

This section describes the supported (and not yet supported) commands. It lists

the SCPI syntax,
registers and bits that are used,

digital input registers

query the registers of a digital input, set filter and fan-out to IEEE488.2 Operation Status register

bits:

0: GP20
1: GP21
2: GP27

registers:

CONDition
PTRansition
NTRansition
EVENt
ENABle

fan-out to IEEE488.2:

Operation Status[0]

SCPI

STATus:OPERation:DIGItal:INPut:CONDition?
STATus:OPERation:DIGItal:INPut:PTRansition
STATus:OPERation:DIGItal:INPut:PTRansition?
STATus:OPERation:DIGItal:INPut:NTRansition
STATus:OPERation:DIGItal:INPut:NTRansition?
STATus:OPERation:DIGItal:INPut:EVENt?
STATus:OPERation:DIGItal:INPut:ENABle
STATus:OPERation:DIGItal:INPut:ENABle?

Example

To run your first LabVIEW flow on the instrument, go to the Downloads section below, and get the latest firmware and LabVIEW VI driver with examples.

VI read analogue pin

This is one of the examples that's included in the LabVIEW VI Driver download

PyVISA control and query digital output pins

ANA:OUT test at 100, 75, 50, 25 and 0%

Extensions

Connect an ADS1115 ADC to Pico I2C0 (GP4[SDA], GP5[SCL]) to enable the get analog input (high resolution) function.

Contributors

shabaz	analogue output, high resolution analogue support, code reviews
ggabe	IEEE488.2 service request support

If you want to contribute to this project, check PST.. Have you worked with the Pico SCPI labTool? and github instructions.

If you want to use this project start your own SCPI instrument, check these 2 posts:

Downloads

The release has all you need to get started. The firmware contains the binary .uf2 that you can copy on your Pico. The LabVIEW VI Driver contains examples that you can run right away.

software	latest release (source and bin)	development branch (source)
Pico Firmware	github release	github branch
LabVIEW Virtual Instrument driver with examples	github release	github branch