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PST.. Program the Pico SCPI labTool?

Jan Cumps
PST.. Program the Pico SCPI labTool?

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.

image

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 

image

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

image

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

image

 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

image

 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

image

 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  !
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

image

 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  
SCPI ANAlog:OUTPut#:RAW <0-4095> inputs:
pin (int)
Duty cycle value (integer 0-4095)
outputs:
na
VI

Public/Action-Status/Analog Out Control

image

 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  
SCPI ANAlog:OUTPut#:RAW? inputs:
pin (int)
outputs:
Duty cycle value (integer 0-4095)
VI

Public/Data/Read Analog Out

image

 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

image

 inputs:
VISA url
outputs:
na

close resource release connection
SCPI na, disconnect via VISA API client dependent
VI

Public/Close

image

 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

image image 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%

image

Extensions

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

Contributors

   analogue output, high resolution analogue support,
code reviews
   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

link to all posts

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