STM32CubeF4/Projects/STM32446E_EVAL/Examples/CEC/CEC_DataExchange/readme.txt

/**
  @page CEC CEC_DataExchange example
  
  @verbatim
  ******************** (C) COPYRIGHT 2017 STMicroelectronics *******************
  * @file    CEC/CEC_DataExchange/readme.txt 
  * @author  MCD Application Team
  * @brief   Description of the CEC Data Exchangeexample.
  ******************************************************************************
  *
  * Redistribution and use in source and binary forms, with or without modification,
  * are permitted provided that the following conditions are met:
  *   1. Redistributions of source code must retain the above copyright notice,
  *      this list of conditions and the following disclaimer.
  *   2. Redistributions in binary form must reproduce the above copyright notice,
  *      this list of conditions and the following disclaimer in the documentation
  *      and/or other materials provided with the distribution.
  *   3. Neither the name of STMicroelectronics nor the names of its contributors
  *      may be used to endorse or promote products derived from this software
  *      without specific prior written permission.
  *
  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
  * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  *
  ******************************************************************************
  @endverbatim

@par Example Description 

How to configure and use the CEC peripheral to receive and transmit messages.

- Hardware Description

To use this example, two STM32446E-EVAL boards (called Device_1 and 
Device_2) are loaded with the same software then connected through CEC lines

 /|\  In the firmware file main.h, uncomment the dedicated line to use
/_!_\ the CEC peripheral as STM32 device_1 or STM32 device_2.

@verbatim
*------------------------------------------------------------------------------*
|           STM32446E_EVAL                          STM32446E_EVAL             |
|         Device Address :0x01                    Device Address :0x03         |
|         ____________________                   ____________________          |
|        |                    |                 |                    |         |
|        |             3.3V   |                 |                    |         | 
|        |               |    |                 |                    |         | 
|        |             27Kohm |                 |                    |         | 
|        |               |    |                 |                    |         | 
|        |         PB3/PB6 O--|-----------------|--O PB3/PB6         |         |
|        |                    |                 |                    |         |
|        |  O LD1             |                 |  O LD1             |         |
|        |  O LD2    Joystick |                 |  O LD2    Joystick |         |
|        |  O LD3        _    |                 |  O LD3        _    |         |
|        |  O LD4       |_|   |                 |  O LD4       |_|   |         |
|        |                    |                 |                    |         |
|        |             GND O--|-----------------|--O GND             |         |
|        |____________________|                 |____________________|         |
|                                                                              |
|                                                                              |
*------------------------------------------------------------------------------**
@endverbatim


- Software Description

The test unrolls as follows.

On TX side, four possible messages can be transmitted and are indicated as
below on the transmitting board:
 - when User push-button is pressed, LED1 toggles
 - when Joystick Selection push-button is pressed, LED2 toggles
 - when Joystick UP push-button is pressed, LED3 toggles
 - when Joystick DOWN push-button is pressed, LED4 toggles

Accordingly, the following happens on the RX side in case of successful
reception:
 - when User push-button is pressed on TX side, 
     * all RX side LEDs are turned off 
 - when Joystick Selection push-button is pressed on TX side, on RX side
     *  LED1 and LED2 are turned on
     *  LED3 and LED4 are turned off 
 - when Joystick UP push-button is pressed on TX side, 
     *  all RX side LEDs are turned on
 - when Joystick DOWN push-button is pressed on TX side, on RX side 
     * LED1 and LED2 are turned off
     * LED3 and LED4 are turned on    
In case of unsuccessful reception, LED3 is turned on.

Practically, 2 EXTI lines (EXTI15_10 and EXTI0) are configured to 
generate an interrupt on each falling or rising edge. 
A specific message is then transmitted by the CEC IP
and a LED connected to a specific MFX GPIO pin is toggled.
    - EXTI0 is mapped to MFX used to manage Joystick pins
    - EXTI15_10 is mapped to PC.13

Then, on TX side,
  - when rising edge is detected on EXTI0-SEL joystick button, LED2 toggles
  - when falling edge is detected on EXTI15_10 and EXTI line interrupt is detected
    on PC.13, LED1 toggles
  - when falling edge is detected on EXTI0-UP joystick button, LED3 toggles
  - when falling edge is detected on EXTI0-DOWN joystick button LED4 toggles
   

In this example, HCLK is configured at 180 MHz.

@par Keywords

Connectivity, CEC, Transmission, Reception, joystick, Data exchange

@par Directory contents 

  - CEC/CEC_DataExchange/Inc/stm32f4xx_hal_conf.h    HAL configuration file
  - CEC/CEC_DataExchange/Inc/stm32f4xx_it.h          Interrupt handlers header file
  - CEC/CEC_DataExchange/Inc/main.h                  Header for main.c module  
  - CEC/CEC_DataExchange/Src/stm32f4xx_it.c          Interrupt handlers
  - CEC/CEC_DataExchange/Src/system_stm32f4xx.c      STM32F4xx system source file
  - CEC/CEC_DataExchange/Src/main.c                  Main program
  - CEC/CEC_DataExchange/Src/stm32f4xx_hal_msp.c     IP hardware resources initialization
  
@par Hardware and Software environment

  - This example runs on STM32F446xx devices.
    
  - This example has been tested with STM32446E-EVAL board and can be
    easily tailored to any other supported device and development board.      


@par How to use it ? 

In order to make the program work, you must do the following :
 - Open your preferred toolchain 
 - in main.h, uncomment DEVICE_1 for first board, uncomment DEVICE_2 for second board
 - Rebuild all files and load your image into target memory
 - Be aware that PB6 pin is missing but PB3 is connected directly to it (SB23 is closed).
 - With a wire, connect PB3-PB3 between the 2 boards
 - Add a pull-up resistor of 27kohm between PB3 and V3.3
 - Connect the ground of the 2 boards
 - Run the example

 * <h3><center>&copy; COPYRIGHT STMicroelectronics</center></h3>
 */