pyusbiss 0.2.0

A Python module for interfacing with USB-ISS multifunction USB Communication Module

pyusbiss

A Python API module for interfacing with USB-ISS multifunction USB Communication Module.

From the USB-ISS’s webpage:

The USB-ISS Multifunction USB Communications Module provides a complete interface between your PC and the I2C bus, SPI bus, a Serial port and general purpose Analogue Input or Digital I/O. The module is powered from the USB. Operating voltage is selectable between 3.3v and 5v and can supply up to 80mA at 5v for external circuitry from a standard 100mA USB port.

• Python 3 (2 TODO)

• Requires pyserial

• Free software: MIT license

• Documentation: https://pyusbiss.readthedocs.io.

Features

Planned features

• Configure USB-ISS to different operating modes; I2C, SPI, I/O and serial

  • For each mode, the API will mimic the popular APIs such as py-spidev for SPI by having same method and properties names. These names will be used in duck typing. This will ensure miminal adaption of applications wishing to use USB-ISS for prototyping and testing.

• Query status of USB-ISS

• Send bytes to and read from components via USB-ISS

Current implementation

• The SPI mode is implemented with following methods and properties

  • Methods

    • xfer - send N bytes and read N bytes back.

  • Properties

    • mode - SPI modes. Please note that USB-ISS’s SPI modes don’t match up with official SPI modes. Use official SPI mode numbers and the API will configure the USB-ISS correctly.

• Other modes are not implemented.

Installation

pip install pyusbiss

Usage

• USBISS only

Connect to your USB-ISS and get information about your USB-ISS.

from usbiss.usbiss import USBISS

port = 'COM4' # Windows
port = '/dev/ttyACM0' # Linux

cxn = USBISS(port)
print(repr(cxn)))

• SPI mode

Initiate USB-ISS with SPI mode and open a port.

from usbiss.spi import SPI

spi = SPI(port)

spi.mode = 1
spi.max_speed_hz = 500000

print(repr(spi._usbiss))

# SPI transaction

response = spi.xfer([0x00, 0x00])

• I2C mode

  TODO

• I/O mode

  TODO

• Serial mode

  TODO

More Information

• USB-ISS’S webpage

Applications

• Alphasense OPC via dhhagan’s py-opc module using the SPI protocol.

Credits

The project was developed during a NERC’s placement at University of Leeds.

This package was created with Cookiecutter and the audreyr/cookiecutter-pypackage project template.

Inspired by Waggle’s alphasense.py, where most of USB-ISS functions were copied over.

History

0.1.0 (2016-09-02)

• Initialised project

0.1.1 (2018-03-08)

• functional usbiss control and spi control.

0.1.2 (2018-03-08)

• Changed SPI mode scheme to official SPI scheme rather than USB-ISS scheme.

• Clarifies project mission in README.rst

0.2.0 (2018-03-10)

• Refactored the codebase so that each protocol can be controlled by its own class. This means a breaking change in the interface.

• SPI and USBISS support only in this release with updated usage.

• Added SPI tests.

• Updated README.rst with new interface.