/**
  @page CRC_UserDefinedPolynomial User-defined generating polynomial CRC Example started by Linux Remote Processor Framework

  @verbatim
  ******************** (C) COPYRIGHT 2019 STMicroelectronics *******************
  * @file    CRC/CRC_UserDefinedPolynomial/Remoteproc/README
  * @author  MCD Application Team
  * @brief   How to run example using Linux Remote Processor Framework
  ******************************************************************************
  * @attention
  *
  * <h2><center>&copy; Copyright (c) 2019 STMicroelectronics.
  * All rights reserved.</center></h2>
  *
  * This software component is licensed by ST under BSD 3-Clause license,
  * the "License"; You may not use this file except in compliance with the
  * License. You may obtain a copy of the License at:
  *                        opensource.org/licenses/BSD-3-Clause
  *
  ******************************************************************************
  @endverbatim

@par Description of M4 Cube example with Linux Remote Processor Framework

When Cube firmware is running on Cortex-M4, System Clock tree and regulators(vrefbuf) are configured by Cortex-A7
Besides, clock source for each peripheral assigned to Cortex-M4 is done by Cortex-A7.


@par How to use it ?

In order to make the program work with Linux running on Cortex-A7, you must do the following :
Before running M4 Cube example, you have to
1) interrupt uboot
2) choose the right configuration to make sure that M4 resources are assigned to Linux Resource Manager driver

Then,
 - Start example using the following command: "fw_cortex_m4.sh start" under example directory installed in userfs partition
     * it will load and start firmware using Linux Remote Processor
 - Stop example using the following command: "fw_cortex_m4.sh stop" under example directory installed in userfs partition
     * it will stop firmware using Linux Remote Processor

@par Example Description
How to configure the CRC using the HAL API. The CRC (cyclic
redundancy check) calculation unit computes the 8-bit CRC code for a given
buffer of 32-bit data words, based on a user-defined generating polynomial.
In this example, the polynomial is set manually to 0x9B, that is,
X^7 + X^4 + X^3 + X + 1.

At the beginning of the main program the HAL_Init() function is called to reset 
all the peripherals, initialize the systick.
Then the System clock source is configured by the SystemClock_Config() function in case of Engineering Mode, this clock configuration is done
by the Firmware running on the Cortex-A7 in case of Production Mode.

The CRC peripheral configuration is ensured by HAL_CRC_Init() function.
The latter is calling HAL_CRC_MspInit() function which core is implementing
the configuration of the needed CRC resources according to the used hardware (CLOCK). 
You can update HAL_CRC_Init() input parameters to change the CRC configuration.

The calculated CRC code is stored in uwCRCValue variable.
Once calculated, the CRC value (uwCRCValue) is compared to the CRC expected value (uwExpectedCRCValue).

STM32 board LED is used to monitor the example status:
  - LED4 is ON when the correct CRC value is calculated
  - LED4 is slowly blinking (1 sec. period) when there is an error in initialization or if an incorrect CRC value is calculated.

@note Care must be taken when using HAL_Delay(), this function provides accurate delay (in milliseconds)
      based on variable incremented in SysTick ISR. This implies that if HAL_Delay() is called from
      a peripheral ISR process, then the SysTick interrupt must have higher priority (numerically lower)
      than the peripheral interrupt. Otherwise the caller ISR process will be blocked.
      To change the SysTick interrupt priority you have to use HAL_NVIC_SetPriority() function.
      
@note The example needs to ensure that the SysTick time base is always set to 1 millisecond
 to have correct HAL operation.


@par Keywords

Security, CRC, CRC Polynomial, IEC 60870-5, hardware CRC, user-defined, generating polynomial


@par Directory contents 
  
  - CRC/CRC_UserDefinedPolynomial/Inc/stm32mp1xx_hal_conf.h    HAL configuration file
  - CRC/CRC_UserDefinedPolynomial/Inc/stm32mp1xx_it.h          Interrupt handlers header file
  - CRC/CRC_UserDefinedPolynomial/Inc/main.h                  Header for main.c module
  - CRC/CRC_UserDefinedPolynomial/Src/stm32mp1xx_it.c          Interrupt handlers
  - CRC/CRC_UserDefinedPolynomial/Src/main.c                  Main program
  - CRC/CRC_UserDefinedPolynomial/Src/stm32mp1xx_hal_msp.c     HAL MSP module 
  - CRC/CRC_UserDefinedPolynomial/Src/system_stm32mp1xx.c      STM32MP1xx system source file

     
@par Hardware and Software environment

  - This example runs on STM32MP157CAAx devices.
  - This example has been tested with STM32MP157C-EV1 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 
 - Rebuild all files and load your image into target memory
 - Run the example
 
 * <h3><center>&copy; COPYRIGHT STMicroelectronics</center></h3>
 */
 