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75 lines
2.0 KiB
ReStructuredText
75 lines
2.0 KiB
ReStructuredText
:mod:`customdevices` -- Custom Devices
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===========================================
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.. automodule:: pybricks.customdevices
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:no-members:
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Analog Sensor
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^^^^^^^^^^^^^
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.. autoclass:: pybricks.customdevices.AnalogSensor
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I2C Device
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^^^^^^^^^^^^^
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.. autoclass:: pybricks.customdevices.I2CDevice
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.. _i2caddress:
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I2C Addresses
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---------------
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I2C addresses are 7-bit values. However, most vendors who make LEGO compatible
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sensors provide an 8-bit address in their documentation.
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To use those addresses, you must shift them by 1 bit.
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For example, if the documented address is ``0xD2``, you must do::
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ev3 = EV3Brick()
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dev = I2CDevice(ev3.Port.S2, address=0xD2>>1)
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Advanced I2C Commands
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----------------------
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The ``I2CDevice`` class methods call functions from the Linux SMBus driver.
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The snippet below illustrates which functions get called exactly.
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Some rudimentary I2C devices do not require a register/command argument. You
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can get this behavior by setting ``reg=None``. This is shown below.
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**Initialize**
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::
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# Initialize
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ev3 = EV3Brick()
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dev = I2CDevice(ev3.Port.S2, address=0x69)
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**Advanced read methods**
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::
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# Recommended for reading. This calls i2c_smbus_read_i2c_block_data.
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result, = dev.read(reg=0x0F, length=1)
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# No register, read 1 byte. This calls i2c_smbus_read_byte.
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dev.read(reg=None, length=1)
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# No register, read, no data.
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# This calls i2c_smbus_write_quick wth I2C_SMBUS_READ.
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dev.read(reg=None, length=0)
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**Advanced write methods**
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::
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# Recommended for writing. This calls i2c_smbus_write_i2c_block_data.
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dev.write(reg=0x22, data=(0x08,))
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# No register, write 1 byte. This calls i2c_smbus_write_byte.
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dev.write(reg=None, data=(0x05,))
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# No register, write, no data.
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# This calls i2c_smbus_write_quick with I2C_SMBUS_WRITE.
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dev.write(reg=None, data=None)
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More details about using I2C without MicroPython can be found on
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the `ev3dev I2C`_ page.
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.. _ev3dev I2C: http://docs.ev3dev.org/projects/lego-linux-drivers/en/ev3dev-stretch/i2c.html
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