149 lines
7.1 KiB
Plaintext
149 lines
7.1 KiB
Plaintext
/**
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@page UART_TwoBoards_ComDMA UART Two Boards Communication DMA example
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@verbatim
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******************************************************************************
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* @file UART/UART_TwoBoards_ComDMA/readme.txt
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* @author MCD Application Team
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* @brief Description of the UART Two Boards Communication DMA example.
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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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UART transmission (transmit/receive) in DMA mode
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between two boards.
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Board: STM32F769I-DISCOVERY (embeds a STM32F769xx device)
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Tx Pin: CN4.D1
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Rx Pin: CN4.D0
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_________________________ _________________________
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| ______________| |______________ |
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| |USART | | USART| |
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| | | | | |
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| | TX |_____________________| RX | |
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| | | | | |
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| | | | | |
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| | | | | |
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| | RX |_____________________| TX | |
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| | | | | |
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| |______________| |______________| |
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| | | |
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| GND|_____________________|GND |
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|_STM32_Board 1___________| |_STM32_Board 2___________|
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Two identical boards are connected as shown on the picture above.
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Board 1: transmitting then receiving board
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Board 2: receiving then transmitting board
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The user presses the User push-button on board 1.
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Then, board 1 sends in DMA mode a message to board 2 that sends it back to
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board 1 in DMA mode as well.
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Finally, board 1 and 2 compare the received message to that sent.
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If the messages are the same, the test passes.
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WARNING: as both boards do not behave the same way, "TRANSMITTER_BOARD" compilation
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switch is defined in /Src/main.c and must be enabled
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at compilation time before loading the executable in the board that first transmits
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then receives.
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The receiving then transmitting board needs to be loaded with an executable
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software obtained with TRANSMITTER_BOARD disabled.
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STM32F769I-DISCOVERY board LED is used to monitor the transfer status:
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- While board 1 is waiting for the user to press the User push-button, its LED1 is
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blinking rapidly (100 ms period).
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- While board 2 is waiting for the message from board 1, its LED1 is emitting
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a couple of flashes every half-second.
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- When the test passes, LED1 on both boards is turned on, otherwise the test has failed.
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- If there is an initialization or transfer error, LED1 is slowly blinking (1 sec. period).
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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) to run at 216 MHz.
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The UART is configured as follows:
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- BaudRate = 9600 baud
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- Word Length = 8 bits (8 data bits, no parity bit)
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- One Stop Bit
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- No parity
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- Hardware flow control disabled (RTS and CTS signals)
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- Reception and transmission are enabled in the time
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@note USARTx/UARTx instance used and associated resources can be updated in "main.h"
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file depending hardware configuration used.
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@note When the parity is enabled, the computed parity is inserted at the MSB
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position of the transmitted data.
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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 need 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 Keywords
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Connectivity, UART, Baud rate, RS-232, Full-duplex, DMA, Parity, Stop bit, Transmission, Reception,
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@Note<74>If the user code size exceeds the DTCM-RAM size or starts from internal cacheable memories (SRAM1 and SRAM2),that is shared between several processors,
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<20><><EFBFBD><EFBFBD><EFBFBD>then it is highly recommended to enable the CPU cache and maintain its coherence at application level.
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<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>The address and the size of cacheable buffers (shared between CPU and other masters) must be properly updated to be aligned to cache line size (32 bytes).
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@Note It is recommended to enable the cache and maintain its coherence, but depending on the use case
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<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD> It is also possible to configure the MPU as "Write through", to guarantee the write access coherence.
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<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>In that case, the MPU must be configured as Cacheable/Bufferable/Not Shareable.
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<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Even though the user must manage the cache coherence for read accesses.
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<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Please refer to the AN4838 <20>Managing memory protection unit (MPU) in STM32 MCUs<55>
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<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Please refer to the AN4839 <20>Level 1 cache on STM32F7 Series<65>
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@par Directory contents
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- UART/UART_TwoBoards_ComDMA/Inc/stm32f7xx_hal_conf.h HAL configuration file
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- UART/UART_TwoBoards_ComDMA/Inc/stm32f7xx_it.h DMA interrupt handlers header file
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- UART/UART_TwoBoards_ComDMA/Inc/main.h Header for main.c module
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- UART/UART_TwoBoards_ComDMA/Src/stm32f7xx_it.c DMA interrupt handlers
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- UART/UART_TwoBoards_ComDMA/Src/main.c Main program
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- UART/UART_TwoBoards_ComDMA/Src/stm32f7xx_hal_msp.c HAL MSP module
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- UART/UART_TwoBoards_ComDMA/Src/system_stm32f7xx.c STM32F7xx system source file
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@par Hardware and Software environment
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- This example runs on STM32F769xx/STM32F767xx/STM32F777xx/STM32F779xx devices.
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- This example has been tested with two STM32F769I-DISCOVERY boards embedding
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a STM32F769xx device and can be easily tailored to any other supported device
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and development board.
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- STM32F769I-DISCOVERY set-up
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- Connect a wire between 1st board CN13.D1 pin (Uart Tx) and 2nd board CN13.D0 pin (Uart Rx)
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- Connect a wire between 1st board CN13.D0 pin (Uart Rx) and 2nd board CN13.D1 pin (Uart Tx)
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- Connect 1st board GND to 2nd Board GND
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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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