Metadata-Version: 2.1
Name: i2cdevice
Version: 0.0.6
Summary: Python DSL for interacting with SMBus-compatible i2c devices
Home-page: http://www.pimoroni.com
Author: Philip Howard
Author-email: phil@pimoroni.com
License: MIT
Project-URL: GitHub, https://www.github.com/pimoroni/i2cdevice-python
Keywords: Raspberry Pi,SMBUS,i2c
Classifier: Development Status :: 5 - Production/Stable
Classifier: Operating System :: POSIX :: Linux
Classifier: License :: OSI Approved :: MIT License
Classifier: Intended Audience :: Developers
Classifier: Programming Language :: Python :: 2.6
Classifier: Programming Language :: Python :: 2.7
Classifier: Programming Language :: Python :: 3
Classifier: Topic :: Software Development
Classifier: Topic :: System :: Hardware
License-File: LICENSE.txt

i2cdevice
=========

|Build Status| |Coverage Status| |PyPi Package| |Python Versions|

i2cdevice is a python domain-specific language aimed at dealing with
common SMBus/i2c device interaction patterns.

This project aims to make group-up implementations of Python libraries
for i2c devices easier, simpler and inherently self-documenting.

It does this by separating a detailed description of the hardware
registers and how they should be manipulated into a stuctured definition
language.

This project does not aim to help you make a public API for Python
devices- that should be built on top of the fundamentals presented here.

Using This Library
==================

You should generally aim for a 1:1 representation of the hardware
registers in the device you're implementing, even if you don't plan to
use all the functionality. Having the full register set implemented
allows for the easy addition of new features in future.

Checkout the libraries listed below for real-world examples.

Features
========

-  Classes for describing devices, registers and individual bit fields
   within registers in a fashion which maps closely with the datasheet
-  Value translation from real world numbers (such as ``512ms``) to
   register values (such as ``0b111``) and back again
-  Read registers into a namedtuple of fields using ``get``
-  Write multiple register fields in a transaction using ``set`` with
   keyword arguments
-  Support for treating multiple-bytes as a single value, or single
   register with multiple values

Built With i2cdevice
====================

-  bme280 - https://github.com/pimoroni/bme280-python
-  bmp280 - https://github.com/pimoroni/bmp280-python
-  bh1745 - https://github.com/pimoroni/bh1745-python
-  as7262 - https://github.com/pimoroni/as7262-python
-  lsm303d - https://github.com/pimoroni/lsm303d-python
-  ltr559 - https://github.com/pimoroni/ltr559-python

Examples
========

The below example defines the ``ALS_CONTROL`` register on an ltr559,
with register address ``0x80``.

It has 3 fields; gain - which is mapped to real world values - and
sw\_reset/mode which are single bit flags.

.. code:: python

    ALS_CONTROL = Register('ALS_CONTROL', 0x80, fields=(
        BitField('gain', 0b00011100, values_map={1: 0b000, 2: 0b001, 4: 0b011, 8:0b011, 48:0b110, 96:0b111}),
        BitField('sw_reset', 0b00000010),
        BitField('mode', 0b00000001)
    ))

A lookup table is not required for values, however, a function can be
used to translate values from and to a format that the device
understands.

The below example uses ``i2cdevice._byte_swap`` to change the endianness
of two 16bit values before they are stored/retrieved.

.. code:: python

    # This will address 0x88, 0x89, 0x8A and 0x8B as a continuous 32bit register
    ALS_DATA = Register('ALS_DATA', 0x88, fields=(
        BitField('ch1', 0xFFFF0000, bitwidth=16, values_in=_byte_swap, values_out=_byte_swap),
        BitField('ch0', 0x0000FFFF, bitwidth=16, values_in=_byte_swap, values_out=_byte_swap)
    ), read_only=True, bitwidth=32)

A "Register" and its "BitField"s define a set of rules and logic for
detailing with the hardware register which is intepreted by the device
class. Registers are declared on a device using the ``registers=()``
keyword argument:

.. code:: python

    I2C_ADDR = 0x23
    ltr559 = Device(I2C_ADDR, bit_width=8, registers=(
        ALS_CONTROL,
        ALS_DATA
    ))

Reading Registers
-----------------

One configured a register's fields can be read into a namedtuple using
the ``get`` method:

.. code:: python

    register_values = ltr559.get('ALS_CONTROL')
    gain = register_values.gain
    sw_reset = register_values.sw_reset
    mode = register_values.mode

Writing Registers
-----------------

The namedtuple returned from ``get`` is immutable and does not attempt
to map values back to the hardware, in order to write one or more fields
to a register you must use ``set`` with a keyword argument for each
field:

.. code:: python

    ltr559.set('ALS_CONTROL',
               gain=4,
               sw_reset=1)

This will read the register state from the device, update the bitfields
accordingly and write the result back.

.. |Build Status| image:: https://travis-ci.com/pimoroni/i2cdevice-python.svg?branch=master
   :target: https://travis-ci.com/pimoroni/i2cdevice-python
.. |Coverage Status| image:: https://coveralls.io/repos/github/pimoroni/i2cdevice-python/badge.svg?branch=master
   :target: https://coveralls.io/github/pimoroni/i2cdevice-python?branch=master
.. |PyPi Package| image:: https://img.shields.io/pypi/v/i2cdevice.svg
   :target: https://pypi.python.org/pypi/i2cdevice
.. |Python Versions| image:: https://img.shields.io/pypi/pyversions/i2cdevice.svg
   :target: https://pypi.python.org/pypi/i2cdevice

0.0.6
-----

* New API methods set and get

0.0.5
-----

* Bump to stable release

0.0.4
-----

* Bugfixes

0.0.3
-----

* Added License

0.0.2
-----

* Major Refactor

0.0.1
-----

* Initial Release
