Overview
========
The spi_polling_board2board_slave example shows how to use spi driver as slave to do board to board transfer with
polling:

Notice: The SPI slave of this example uses interrupt mode, as there is no polling mode for SPI slave.

In this example, one spi instance as slave and another spi instance on other board as master. Master sends a piece of
data to slave, and receive a piece of data from slave. This example checks if the data received from master is correct.

Toolchain supported
===================
- IAR embedded Workbench 7.60.1
- Keil MDK 5.18a
- GCC ARM Embedded 2015-4.9-q3
- Kinetis Development Studio IDE 3.2.0
- Atollic TrueSTUDIO 5.4.2

Hardware requirements
=====================
- Mini USB cable
- FRDM-KL03Z board
- Personal Computer

Board settings
==============
SPI one board:
  + Transfer data from MASTER_BOARD to SLAVE_BOARD of SPI interface, SPI0 pins of MASTER_BOARD are connected with
    SPI1 pins of SLAVE_BOARD
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
           MASTER_BOARD    CONNECTS TO   SLAVE_BOARD
Pin Name   Board Location                Board Location
MOSI       J2-4                          J2-4
MISO       J2-5                          J2-5
SS         J2-3                          J2-3
CLK        J2-6                          J2-6
GND        J2-7                          J2-7
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Prepare the Demo
================
1.  Connect a mini USB cable between the PC host and the OpenSDA USB port on the board.
2.  Open a serial terminal on PC for OpenSDA serial device with these settings:
    - 9600 baud rate
    - 8 data bits
    - No parity
    - One stop bit
    - No flow control
3.  Download the program to the target board.
4.  Reset the SoC and run the project.

Running the demo
================
When the demo runs successfully, the log would be seen on the OpenSDA terminal like:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Slave is working....
Succeed!
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Customization options
=====================


