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  9.20.1
- Keil MDK  5.34
- GCC ARM Embedded  10.2.1
- MCUXpresso  11.4.1

Hardware requirements
=====================
- Micro USB cable
- Two LPCXpresso55S36 boards
- Personal Computer

Board settings
==============
Short JP51 1-2, JP52 1-2.

Connect SPI slave on board to SPI master on other board
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    Master_board(SPI2)           Slave_board(SPI2)                          
Pin Name   Board Location     Pin Name   Board Location                     
MISO       J122  pin 12       MISO       J122  pin 12 
MOSI       J8    pin 3        MOSI       J8    pin 3
SCK        J122  pin 8        SCK        J122  pin 8
SSEL0      J122  pin 6        SSEL0      J122  pin 6
GND        J92   pin 14       GND        J92   pin 14
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Prepare the Demo
================
1.  Connect a micro USB cable between the PC host and the CMSIS DAP USB port (J1) on the board
2.  Open a serial terminal with the following settings (See Appendix A in Getting started guide for description how to determine serial port number):
    - 115200 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 CMSIS DAP terminal like:

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Slave is working....

Succeed!
​~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
