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SPI.rst

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:mod:`SPI` --- Serial Peripheral Interface

This module defines an object type that allows Serial Peripheral Interface (SPI) bus transactions on hosts running the Linux kernel. The host kernel must have SPI support and SPI device interface support.

Because the SPI device interface is opened R/W, users of this module usually must have root permissions or be members of a group with granted access rights.

Pins used for SPI0 and SPI1

PORT CS0 DO DI SCLK
SPI0 P9_17 P9_21 P9_18 P9_22
SPI1 P9_28 P9_29 P9_30 P9_31

Example:

import Adafruit_BBIO.SPI as SPI

from Adafruit_BBIO.SPI import SPI
# spi = SPI(bus, device) #/dev/spidev<bus>.<device>

# /dev/spidev0.0
spi = SPI(1, 0)
print(spi.xfer2([32, 11, 110, 22, 220]))
spi.close()

# /dev/spidev0.1
spi = SPI(1, 1)
print(spi.xfer2([32, 11, 110, 22, 220]))
spi.close()

# /dev/spidev1.0
spi = SPI(2, 0)
print(spi.xfer2([32, 11, 110, 22, 220]))
spi.close()

# /dev/spidev1.1
spi = SPI(2, 1)
print(spi.xfer2([32, 11, 110, 22, 220]))
spi.close()

.. module:: Adafruit_BBIO.SPI
param bus:bus number.
param client:client device number.
returns:a new SPI object, optionally connected to the specified SPI device interface.
rtype::class:`SPI` 
.. attribute:: bpw

   Bits per word.


.. attribute:: cshigh

   Chip Select (CS or Slave Select, SS) active high.


.. attribute:: loop

   Loopback configuration.


.. attribute:: lsbfirst

   Least Significant Bit (LSB) first.


.. attribute:: mode

   SPI mode as two bit pattern of Clock Polarity and Phase [CPOL|CPHA]; min-- 0b00 = 0, max-- 0b11 = 3.


.. attribute:: msh

   Maximum speed in Hz.


.. attribute:: threewire

   SI/SO signals are shared.


.. method:: open(bus, device)

   Connects the object to the specified SPI device. `open(X, Y)` will open
   `/dev/spidev-X.Y`

   :param int bus: bus number
   :param str device: device number


.. method:: close()

   Disconnects the object from the interface.


.. method:: readbytes(len)

   Read the specified length of bytes from the SPI device.

   :param int len: length of bytes to read, 1024 maximum.
   :returns: values read
   :rtype: list[int]


.. method:: writebytes(values)

   Write bytes to the SPI device.

   :param values: list of values to write, with a maximum length of 1024.
   :type values: list[int]


.. method:: xfer(values[,delay=0])

   Perform an SPI transaction of values. Slave Select (SS or CS) will be
   released and reactivated between blocks.

   :param values: list of values to transfer, with a maximum length of 1024.
   :type values: list[int]
   :param delay: delay in microseconds between blocks.
   :returns: values transferred
   :rtype: list[int]


.. method:: xfer2(values)

   Perform an SPI transaction of values. Slave Select (SS or CS) will be
   held active between blocks.

   :param values: list of values to transfer, with a maximum length of 1024.
   :type values: list[int]
   :returns: values transferred
   :rtype: list[int]