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pybricks-api/doc/api/customdevices.rst
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Laurens Valk 22bbca3e24 doc/customdevices: simplify I2C docs
remove smbus information, point to source code instead.
2019-12-06 15:16:06 +01:00

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:mod:`customdevices` -- Custom Devices
===========================================
.. automodule:: pybricks.customdevices
:no-members:
Analog Sensor
^^^^^^^^^^^^^
.. autoclass:: pybricks.customdevices.AnalogSensor
I2C Device
^^^^^^^^^^^^^
.. autoclass:: pybricks.customdevices.I2CDevice
.. _i2caddress:
I2C Addresses
---------------
I2C addresses are 7-bit values. However, most vendors who make LEGO compatible
sensors provide an 8-bit address in their documentation.
To use those addresses, you must shift them by 1 bit.
For example, if the documented address is ``0xD2``, you must do::
ev3 = EV3Brick()
dev = I2CDevice(ev3.Port.S2, address=0xD2>>1)
Advanced I2C Commands
---------------------
Some rudimentary I2C devices do not require a register argument or even any
data. You can achieve this behavior as shown in the examples below.
**Initialize**
::
# Initialize
ev3 = EV3Brick()
dev = I2CDevice(ev3.Port.S2, address=0x69)
**Advanced read methods**
::
# Recommended for reading:
result, = dev.read(reg=0x0F, length=1)
# Read 1 byte from no particular register:
dev.read(reg=None, length=1)
# Read 0 bytes from no particular register:
dev.read(reg=None, length=0)
**Advanced write methods**
::
# Recommended for writing:
dev.write(reg=0x22, data=b'\x08')
# Write 1 byte to no particular register:
dev.write(reg=None, data=b'\x08')
# Write 0 bytes to no particular register:
dev.write(reg=None, data=None)
**Additional technical resources**
The ``I2CDevice`` class methods call functions from the Linux SMBus driver.
To find out which commands are called under the hood, check the
`Pybricks source code`_.
More details about using I2C without MicroPython can be found on
the `ev3dev I2C`_ page.
.. _ev3dev I2C: http://docs.ev3dev.org/projects/lego-linux-drivers/en/ev3dev-stretch/i2c.html
.. _Pybricks source code: https://github.com/pybricks/pybricks-micropython
UART Device
^^^^^^^^^^^^^
.. autoclass:: pybricks.customdevices.UARTDevice