118 lines
3.9 KiB
ReStructuredText
118 lines
3.9 KiB
ReStructuredText
.. _machine.I2C:
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class I2C -- a two-wire serial protocol
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=======================================
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I2C is a two-wire protocol for communicating between devices. At the physical
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level it consists of 2 wires: SCL and SDA, the clock and data lines respectively.
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I2C objects are created attached to a specific bus. They can be initialised
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when created, or initialised later on.
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.. only:: port_wipy
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Example::
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from machine import I2C
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i2c = I2C(0) # create on bus 0
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i2c = I2C(0, I2C.MASTER) # create and init as a master
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i2c.init(I2C.MASTER, baudrate=20000) # init as a master
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i2c.deinit() # turn off the peripheral
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Printing the i2c object gives you information about its configuration.
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.. only:: port_wipy
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A master must specify the recipient's address::
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i2c.init(I2C.MASTER)
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i2c.writeto(0x42, '123') # send 3 bytes to slave with address 0x42
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i2c.writeto(addr=0x42, b'456') # keyword for address
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Master also has other methods::
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i2c.scan() # scan for slaves on the bus, returning
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# a list of valid addresses
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i2c.readfrom_mem(0x42, 2, 3) # read 3 bytes from memory of slave 0x42,
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# starting at address 2 in the slave
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i2c.writeto_mem(0x42, 2, 'abc') # write 'abc' (3 bytes) to memory of slave 0x42
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# starting at address 2 in the slave, timeout after 1 second
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Constructors
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------------
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.. only:: port_wipy
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.. class:: machine.I2C(bus, ...)
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Construct an I2C object on the given bus. `bus` can only be 0.
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If the bus is not given, the default one will be selected (0).
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Methods
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-------
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.. method:: i2c.deinit()
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Turn off the I2C bus.
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.. only:: port_wipy
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.. method:: i2c.init(mode, \*, baudrate=100000, pins=(SDA, SCL))
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Initialise the I2C bus with the given parameters:
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- ``mode`` must be ``I2C.MASTER``
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- ``baudrate`` is the SCL clock rate
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- ``pins`` is an optional tuple with the pins to assign to the I2C bus.
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.. method:: i2c.readfrom(addr, nbytes)
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Read ``nbytes`` from the slave specified by ``addr``.
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Returns a ``bytes`` object with the data read.
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.. method:: i2c.readfrom_into(addr, buf)
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Read into ``buf`` from the slave specified by ``addr``.
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Returns the number of bytes read.
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.. method:: i2c.writeto(addr, buf, \*, stop=True)
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Write ``buf`` to the slave specified by ``addr``. Set ``stop`` to ``False``
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if the transfer should be continued.
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Returns the number of bytes written.
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.. method:: i2c.readfrom_mem(addr, memaddr, nbytes, \*, addrsize=8)
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Read ``nbytes`` from the slave specified by ``addr`` starting from the memory
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address specified by ``memaddr``.
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Param ``addrsize`` specifies the address size in bits.
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Returns a ``bytes`` object with the data read.
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.. method:: i2c.readfrom_mem_into(addr, memaddr, buf, \*, addrsize=8)
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Read into ``buf`` from the slave specified by ``addr`` starting from the memory
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address specified by ``memaddr``.
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Param ``addrsize`` specifies the address size in bits.
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Returns the number of bytes read.
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.. method:: i2c.writeto_mem(addr, memaddr, buf, \*, addrsize=8)
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Write ``buf`` to the slave specified by ``addr`` starting from the
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memory address specified by ``memaddr``. Param ``addrsize`` specifies the
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address size in bits.
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Set ``stop`` to ``False`` if the transfer should be continued.
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Returns the number of bytes written.
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.. method:: i2c.scan()
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Scan all I2C addresses from 0x01 to 0x7f and return a list of those that respond.
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Only valid when in master mode.
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Constants
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---------
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.. data:: I2C.MASTER
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for initialising the bus to master mode
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