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.. highlight:: cpp
.. _lang-hardwarespi:
HardwareSPI
===========
This class is used for creating objects to manage the Maple's built-in
SPI ports. The Maple has two SPI ports. The relevant pins
corresponding to each port's logic signals are documented in the
following table (and on the Maple silkscreen):
.. _lang-hardwarespi-pinout:
.. list-table::
:header-rows: 1
* - Port number
- NSS
- MOSI
- MISO
- SCK
* - 1
- 10
- 11
- 12
- 13
* - 2
- 31
- 32
- 33
- 34
If you use a SPI port, you cannot simultaneously use its associated
pins for other purposes.
Library Documentation
---------------------
Using the SPI Class
^^^^^^^^^^^^^^^^^^^
You can declare that you want to use SPI in your sketch by putting
``HardwareSPI Spi(number);`` with your variables, where ``number`` is
1 or 2, depending on which SPI you want to use. Then you can use the
functions described in the next section. For example::
// Use SPI 1
HardwareSpi Spi(1);
void setup() {
Spi.begin(SPI_18MHZ);
}
void loop() {
// Get the next byte from the peripheral
uint8 byte = Spi.recv();
}
HardwareSPI Class Reference
^^^^^^^^^^^^^^^^^^^^^^^^^^^
.. cpp:class:: HardwareSPI
Class for interacting with SPI.
.. cpp:function:: HardwareSPI::HardwareSPI(uint32 spi_num)
Construct an object for managing a SPI peripheral. ``spi_num``
must be 1 or 2; see the :ref:`table above
<lang-hardwarespi-pinout>` for pinout information.
.. cpp:function:: void HardwareSPI::begin(SPIFrequency freq, uint32 endianness, uint32 mode)
Configure the baudrate of the given SPI port and set up the header
pins appropriately.
Parameters:
- ``freq``: one of the ``SPIFrequency`` values, given :ref:`below
<lang-hardwarespi-spifrequency>`.
- ``endianness``: either ``LSBFIRST`` (little-endian) or
``MSBFIRST`` (big-endian).
- ``mode``: one of 0, 1, 2, or 3, and specifies which SPI mode is
used. The mode number determines a combination of polarity and
phase according to the following table:
.. list-table::
:header-rows: 1
* - Mode
- Polarity
- Phase
* - 0
- 0
- 0
* - 1
- 0
- 1
* - 2
- 1
- 0
* - 3
- 1
- 1
For more information on polarity and phase, see the
:ref:`external references, below <lang-hardwarespi-seealso>`.
.. cpp:function:: void HardwareSPI::begin()
A convenience ``begin()``, equivalent to ``begin(SPI_1_125MHZ,
MSBFIRST, 0)``.
.. cpp:function:: uint8 HardwareSpi::send(uint8 *data, uint32 length)
Writes ``data`` into the port buffer to be transmitted as soon as
possible, where ``length`` is the number of bytes to send from
``data``. Returns the last byte shifted back from slave.
.. cpp:function:: uint8 HardwareSpi::send(uint8 data)
Writes the single byte ``data`` into the port buffer to be
transmitted as soon as possible. Returns the data byte shifted
back from the slave.
.. cpp:function:: uint8 HardwareSpi::recv()
Reads a byte from the peripheral. Returns the next byte in the
buffer.
SPI Speeds
^^^^^^^^^^
.. _lang-hardwarespi-spifrequency:
The possible SPI speeds are configured using the ``SPIFrequency`` enum:
.. doxygenenum:: SPIFrequency
.. _lang-hardwarespi-seealso:
See Also
--------
* `Wikipedia Article on Serial Peripheral Interface Bus (SPI)
<http://en.wikipedia.org/wiki/Serial_Peripheral_Interface_Bus>`_
* `Arduino reference on SPI
<http://www.arduino.cc/playground/Code/Spi>`_
* `Hardcore SPI on Arduino <http://klk64.com/arduino-spi/>`_ by kik64
* STMicro documentation for STM32F103RB microcontroller:
* `Datasheet <http://www.st.com/stonline/products/literature/ds/13587.pdf>`_ (pdf)
* `Reference Manual <http://www.st.com/stonline/products/literature/rm/13902.pdf>`_ (pdf)
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