.. _spi_engine control-interface:

SPI Engine Control Interface
================================================================================

The SPI Engine Control Interface is used to exchange data between different
cores within the SPI Engine framework. It is used to exchange the commands and
synchronization points as well as the SPI bus transmit and receive data.

The interface consists of four streams:

* The CMD stream which carries the SPI Engine commands. (Master to Slave)
* The SDO stream which carries the to be transmitted data for the SPI bus.
  (Master to Slave)
* The SDI stream which carries the received data from the SPI bus. (Slave to
  Master)
* The SYNC stream which carries the synchronization events. (Slave to Master)

Each of the streams has a valid, ready and data signal. They follow the
handshaking protocol as defined by the AXI standard. Meaning the master asserts
valid when the data on the data signal is valid and the slave asserts ready when
it is able to accept new data. If both valid and ready are asserted at the same
time the data has been transmitted from the master to the slave.

Files
--------------------------------------------------------------------------------

.. list-table::
   :header-rows: 1

   * - Name
     - Description
   * - :git-hdl:`library/spi_engine/interfaces/spi_engine_ctrl_rtl.xml`
     - Interface definition file

Signal Pins
--------------------------------------------------------------------------------

.. list-table::
   :widths: 10 10 10 70
   :header-rows: 1

   * - Width
     - Name
     - Direction (Master)
     - Description
   * -
     - ``cmd_ready``
     - Input
     - Ready signal of the CMD stream
   * -
     - ``cmd_valid``
     - Output
     - Valid signal of the CMD stream
   * - [15:0]
     - ``cmd_data``
     - Output
     - Data signal of the CMD stream
   * -
     - ``sdo_ready``
     - Input
     - Ready signal of the SDO stream
   * -
     - ``sdo_valid``
     - Output
     - Valid signal of the SDO stream
   * - [DATA_WIDTH-1:0]
     - ``sdo_data``
     - Output
     - Data signal of the SDO stream
   * -
     - ``sdi_ready``
     - Output
     - Ready signal of the SDI stream
   * -
     - ``sdi_valid``
     - Input
     - Valid signal of the SDI stream
   * - [(NUM_OF_SDI*DATA_WIDTH-1):0]
     - ``sdi_data``
     - Input
     - Data signal of the SDI stream
   * -
     - ``sync_ready``
     - Output
     - Ready signal of the SYNC stream
   * -
     - ``sync_valid``
     - Input
     - Valid signal of the SYNC stream
   * - [7:0]
     - ``sync_data``
     - Input
     - Data signal of the sync stream