/**
 * @file        readme.txt
 *
 * @brief       This file is routine instruction
 *
 * @version     V1.0.0
 *
 * @date        2023-12-01
 *
 * @attention
 *
 *  Copyright (C) 2023 Geehy Semiconductor
 *
 *  You may not use this file except in compliance with the
 *  GEEHY COPYRIGHT NOTICE (GEEHY SOFTWARE PACKAGE LICENSE).
 *
 *  The program is only for reference, which is distributed in the hope
 *  that it will be useful and instructional for customers to develop
 *  their software. Unless required by applicable law or agreed to in
 *  writing, the program is distributed on an "AS IS" BASIS, WITHOUT
 *  ANY WARRANTY OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the GEEHY SOFTWARE PACKAGE LICENSE for the governing permissions
 *  and limitations under the License.
 */

&par Example Description

This example shows how to use RS485 module to communicate between eval board and serial COM by interrupt.
eval board uses UART3 to send a string and then enters the data waiting for serial COM to return data, 
while serial COM uses RS485 module to receive the string of eval board, and then sends back the data. 
If the data received and sent are inconsistent, the LED3 of eval board will turn off, otherwise LED3 will turn on.

&par Hardware Description

  - RS485_EN(PF15)
  - USART3_TX(PB10)
  - USART3_RX(PB11)
  - USART3 configured as follow:
  - BaudRate = 115200
  - Word Length = USART_WordLength_8b
  - Stop Bit = USART_StopBits_1
  - Parity = USART_Parity_No
  - Hardware flow control disabled (RTS and CTS signals)
  - Receive and transmit enabled

The RS485 connection as follows:
     _____________                    ____________          ____________
    |             |                  |            |        |            |
    |             |                  |            |-EN  <->|            |
    |             |                  |            |        |            |
    |             |-MAX485-A <--> A- |            |-TX  <->|            |
    |             |                  |            |        |            |
    | EVAL Board  |                  | 485 module |-RX  <->|     PC     |
    |             |                  |            |        |            |
    |             |-MAX485-B <--> B- |            |-VCC <->|            |
    |             |                  |            |        |            |
    |             |                  |            |-GND <->|            |
    |_____________|                  |____________|        |____________|

&par Directory contents

  - USART/UART_RS485/Source/main.c                  Main program
  - USART/UART_RS485/Source/apm32f4xx_int.c         Interrupt handlers

&par IDE environment

  - MDK-ARM V5.36
  - EWARM V8.50.5.26295
  - ECLIPSE-EMB V4.24.0

&par Hardware and Software environment

  - This example runs on APM32F407 EVAL Devices.
