Overview
========
The usart dma ring buffer example shows how to use usart driver with DMA driver used:

In this example, a ring buffer was implemented to receive the characters from PC side, 
to implemente the ring buffer, a descriptor was created and chain itself as the next descriptor,
then the DMA transfer will start a continuous transfer.

While data in the ring buffer reach 8 characters, routine will send them out using DMA mode.


Toolchain supported
===================
- IAR embedded Workbench  9.10.2
- Keil MDK  5.34
- GCC ARM Embedded  10.2.1
- MCUXpresso  11.5.0

Hardware requirements
=====================
- Mini/micro USB cable
- LPCXpresso845MAX board
- Personal Computer

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

Prepare the Demo
================
1.  Connect a micro USB cable between the PC host and the CMSIS DAP USB port on the board
2.  Open a serial terminal with the following settings:
    - 9600 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
================
The log below shows the output of the hello world demo in the terminal window:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
USART DMA ring buffer example
Board will send back received data

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