85 lines
4.0 KiB
Plaintext
85 lines
4.0 KiB
Plaintext
/**
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@page CRC_PolynomialUpdate CRC operation with Polynomial update (HAL/LL mixed usage example)
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@verbatim
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******************** (C) COPYRIGHT 2016 STMicroelectronics *******************
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* @file CRC/CRC_PolynomialUpdate/readme.txt
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* @author MCD Application Team
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* @brief Description of CRC operation including user updates on generating polynomial.
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******************************************************************************
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* @attention
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*
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* Copyright (c) 2016 STMicroelectronics.
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* All rights reserved.
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*
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* This software is licensed under terms that can be found in the LICENSE file
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* in the root directory of this software component.
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* If no LICENSE file comes with this software, it is provided AS-IS.
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*
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******************************************************************************
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@endverbatim
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@par Example Description
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How to use the CRC peripheral through the STM32F0xx CRC HAL and LL API.
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The LL API is used for performance improvement. The CRC calculation unit
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computes the 8-bit CRC code of a given buffer of 32-bit data words, based on
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a user-defined generating polynomial. In this example, the polynomial is first
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set manually to 0x9B (X^8 + X^7 + X^4 + X^3 + X + 1).
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In a second step, the generating polynomial value and length are updated and
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set to 0x1021 (X^16 + X^12 + X^5 + 1) for a new CRC calculation.
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These updates are performed using the CRC LL API.
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At the beginning of the main program the HAL_Init() function is called to reset
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all the peripherals, initialize the Flash interface and the systick.
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Then the SystemClock_Config() function is used to configure the system
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clock (SYSCLK).
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The CRC peripheral configuration is ensured by HAL_CRC_Init() function.
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The latter is calling HAL_CRC_MspInit() function which core is implementing
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the configuration of the needed CRC resources according to the used hardware (CLOCK).
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You can update HAL_CRC_Init() input parameters to change the CRC configuration.
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For each computation, calculated CRC code is stored in uwCRCValue variable.
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Once calculated, the CRC value (uwCRCValue) is compared to the CRC expected value (uwExpectedCRCValue1 and uwExpectedCRCValue2).
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STM32 board LED is used to monitor the example status:
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- LED2 is ON when correct CRC values are calculated
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- LED2 is slowly blinking (1 sec. period) when there is an error in initialization or if an incorrect CRC value is calculated.
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@note Care must be taken when using HAL_Delay(), this function provides accurate delay (in milliseconds)
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based on variable incremented in SysTick ISR. This implies that if HAL_Delay() is called from
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a peripheral ISR process, then the SysTick interrupt must have higher priority (numerically lower)
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than the peripheral interrupt. Otherwise the caller ISR process will be blocked.
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To change the SysTick interrupt priority you have to use HAL_NVIC_SetPriority() function.
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@note The application needs to ensure that the SysTick time base is always set to 1 millisecond
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to have correct HAL operation.
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@par Directory contents
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- CRC/CRC_PolynomialUpdate/Inc/stm32f0xx_hal_conf.h HAL configuration file
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- CRC/CRC_PolynomialUpdate/Inc/stm32f0xx_it.h Interrupt handlers header file
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- CRC/CRC_PolynomialUpdate/Inc/main.h Header for main.c module
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- CRC/CRC_PolynomialUpdate/Src/stm32f0xx_it.c Interrupt handlers
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- CRC/CRC_PolynomialUpdate/Src/main.c Main program
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- CRC/CRC_PolynomialUpdate/Src/stm32f0xx_hal_msp.c HAL MSP module
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- CRC/CRC_PolynomialUpdate/Src/system_stm32f0xx.c STM32F0xx system source file
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@par Hardware and Software environment
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- This example runs on STM32F072xB devices.
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- This example has been tested with STM32F072RB-Nucleo RevC board and can be
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easily tailored to any other supported device and development board.
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@par How to use it ?
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In order to make the program work, you must do the following:
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- Open your preferred toolchain
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- Rebuild all files and load your image into target memory
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- Run the example
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*/
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