Description
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Overview
A sample framework for LabVIEW control of a Raspberry Pi Pico.
The Pico module is a very inexpensive, only costing a few pounds, and can run Python. It includes a large amount of digital IO and has Python routines for SPI and I2C. Connection to the computer is via USB.
Using the Raspberry Pi Pico test fixtures and device controllers can be produced/tested/updated very quickly, and can be controlled by Windows, Mac and Linux.
Description
Attached is some example code, the Python "main.py" to be placed on the Pico module, plus LabVIEW VIs for communicating with the Pico.
The "main.py" Python code is loaded onto the Pico module using Thonny and when run it provides a command prompt where it can be sent commands in plain ASCII text. Some example commands are included, such as a SPI command for communicating with SPI devices. Using a simple text based command line interface allows the added functions to be run and tested from Thonny or any terminal emulator such as Tera Term, Putty etc.
The main LabVIEW routine, "RPiPico - Talk USB.vi", is used to communicate with the Pico device. It looks for a command prompt, and if seen it sends the required command and receives the reply. If the Pico module is in the incorrect mode then control characters are sent to reset/reboot the Pico module and start it running "main.py" again. Also included in the example code are LabVIEW routines for running the individual commands and processing their replies.
One use of this code is for the creation of simple test fixtures for use within automated test systems. Included in the code is a function for writing a fixture title to the Pico file system and having the main.py code setup various port functions on startup as required.
Hardware and Software Requirements
LabVIEW, Raspberry Pi Pico, Thonny.
If using the Pico for SPI/I2C I would suggest using SPI and I2C isolators to allow the control of 3V3 and 5V devices and protect the computer and Pico from any damage from higher voltages.
Steps to Implement or Execute Code
Thonny should be used to prepare the Pico module and to save the "main.py" code to the Pico. The Pico module will auomatically run main.py every time it is started up.
On a Mac NI Max should be used to provide the Pico module with a device alias/address the LabVIEW code can use for communication.
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