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Atlas I2C

Project description

Continuous integration Continous delivery

AtlasI2C: A Python package to communicate with Atlas Scientific devices in I2C mode.

This package provides functionality that is based on the example code from Atlas Scientific. It has the following goals:

  1. Provide a simple and clean codebase with test coverage
  2. Reduce code duplication by making the codebase available from PyPi
  3. Provide comprehensive support for Atlas Scientific EZO sensors

Overview

This package provides the following modules:

module: atlas_i2c

The atlas_i2c module can be thought of as the client that talks to the server, similar to how an HTTP client talks to an HTTP server. The server in this scenario is the Atlas Scientfic EZO sensor. Instead of talking over TCP using HTTP, however, it talks to the server over the I2C bus, using Linux device files (e.g. /dev/i2c-1).

The module uses the following protocol to communicate with a sensor:

  1. Open the device file for reading and writing
  2. Send a command string (e.g. "R") to the device by writing it to the device file
  3. Wait for N milliseconds for the sensor to process the command
  4. Read the resulting data from the device file

At the lowest level, this module's read() and write() methods can be combined with time.sleep() to communicate with a sensor:

In [1]: from atlas_i2c import atlas_i2c
In [2]: sensor_address = 102
In [3]: dev = atlas_i2c.AtlasI2C()
In [4]: dev.set_i2c_address(sensor_address)
In [5]: dev.write("R")
In [6]: time.sleep(1.5)
In [15]: result = dev.read("R")
In [16]: result.status_code
Out[16]: 1
In [17]: result.data
Out[17]: b'0.922'
In [18]: result.original_cmd
Out[18]: 'R'

The module also provides a query() method to conveniently wrap the above protocol into a single method:

In [19]: result = dev.query("R", processing_delay=1500)
In [20]: result.status_code
Out[20]: 1
In [21]: result.data
Out[21]: b'0.926'
In [22]: result.original_cmd
Out[22]: 'R'

The result of calling the read() and query() methods in the above code snippets is a CommandReponse object. Here is an example of creating a CommandResponse object manually and populating it:

In [1]: from atlas_i2c import atlas_i2c
In [2]: response = atlas_i2c.CommandResponse()
In [3]: response
Out[3]: <atlas_i2c.atlas_i2c.CommandResponse at 0x7fbd40f48370>
In [6]: response.sensor_address = 10
In [7]: response.sensor_address = 102
In [8]: response.original_cmd = "R"
In [9]: response.response_type = "str"
In [10]: response.status_code = raw_data[0] 

module: commands

The commands module provides encapsulations intended to simplify interactions with sensors. Command attributes and methods can be accessed at the class level, thus it's not necessary to instantiate a command.

The module defines constants for each command class:

In [19]: from atlas_i2c import commands
# To find the arguments a command supports:
In [24]: commands.BAUD.arguments
Out[24]: (300, 1200, 2400, 9600, 19200, 38400, 57600, 115200)
# To get a formatted command string:
In [25]: commands.BAUD.format_command(300)
Out[25]: 'Baud,300'
# A command may not support any arguments:
In [24]: commands.READ.arguments
In [25]:

Not all commands have been implemented. The format_command method on unimplemented commands will raise a NotImplementedError exception.

module: sensors

The sensors module provides a higher-level encapsulation of a sensor in the form of the Sensor class. The intention is that the Sensor class is used as the primary means of communication; it uses the lower-level AtlasI2C class to perform all functions, such as reading data from a sensor.

In [25]: from atlas_i2c import sensors
In [26]: sensor = sensors.Sensor("Temperature", 102)
In [27]: sensor.connect()
In [28]: response = sensor.query(commands.READ)
In [29]: response.status_code
Out[29]: 1
In [30]: response.data
Out[30]: b'0.923'
In [31]: response.original_cmd
Out[31]: 'R'

Supported Python Versions

This module requires Python >= 3.6.

Tests

atlas_i2c uses Tox for test automation, which includes linting, formatting and static type checking. To run Tox:

> tox
[output truncated]
py38: commands succeeded
py37: commands succeeded
py36: commands succeeded
mypy: commands succeeded
lint: commands succeeded
format: commands succeeded
congratulations :)

Installation

From PyPi

Installation can be done using Pip:

> pip install atlas-i2c

From source

> python setup.py bdist_wheel
> pip install dist/atlas_i2c-$version-py3-none-any.whl

Atlas Scientific Sensor Datasheets

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