Overview
========
The Shell Demo application demonstrates to control Leds by commands.
Note: Please input one character at a time. If you input too many characters each time, the receiver may overflow
because the low level UART uses simple polling way for receiving. If you want to try inputting many characters each time,
just define DEBUG_CONSOLE_TRANSFER_NON_BLOCKING in your project to use the advanced debug console utility.
Besides, the demo does not support semihosting mode. The shell component is based on debug console and 
serial manager. When semihosting is used, debug console and serial manager are bypassed. So the shell demo cannot
work with semihosting.

Toolchain supported
===================
- Keil MDK  5.36
- IAR embedded Workbench  9.20.2
- GCC ARM Embedded  10.3.1
- MCUXpresso  11.5.0

Hardware requirements
=====================
- Mini USB cable
- LPCXpresso55s69 board
- Personal Computer

Board settings
==============
No special settings are required.

Prepare the Demo
================
Note: MCUXpresso IDE project default debug console is semihost
1.  Connect a USB cable between the host PC and the USB port on the target board.
2.  Open a serial terminal with the following settings:
    - 115200 baud rate
    - 8 data bits
    - No parity
    - One stop bit
    - No flow control
3.  Download the program to the target board.
4.  Either press the reset button on your board or launch the debugger in your IDE to begin running the demo.

Running the demo
================
When the example runs successfully, the following message is displayed in the terminal:

~~~~~~~~~~~~~~~~~~~~~
SHELL (build: Jun 19 2020)
Copyright 2020 NXP

SHELL>> help

"help": Lists all the registered commands

"led arg1 arg2":
 Usage:
    arg1: 1|2|3|4...            Led index
    arg2: on|off                Led status

"exit": Exit program

SHELL>> led 1 on
SHELL>> led 1 off
SHELL>> led 2 on
SHELL>> led 2 off
SHELL>> led 3 on
SHELL>> led 3 off
SHELL>> led 4 on
LED index is wrongs
SHELL>>
~~~~~~~~~~~~~~~~~~~~~

Note:
    1,The shell information "SHELL (build: Jun 19 2020)" may be different, which depends on the compile date.
    2,If the command 'led x on'/'led x off' run success, the corresponding LEDx on board will turn on/turn off.
      But the valid "Led index" may be different, which depends how many LEDs are available on the specific board.
      For example: one board only have LED1/LED2, then shell demo will print "LED index is wrong" for all led index bigger than 2.