/**
@page UART_TwoBoards_ComDMA UART Two Boards Communication DMA example
@verbatim
******************************************************************************
* @file UART/UART_TwoBoards_ComDMA/readme.txt
* @author MCD Application Team
* @brief Description of the UART Two Boards Communication DMA example.
******************************************************************************
* @attention
*
* Copyright (c) 2016 STMicroelectronics.
* All rights reserved.
*
* This software is licensed under terms that can be found in the LICENSE file
* in the root directory of this software component.
* If no LICENSE file comes with this software, it is provided AS-IS.
*
******************************************************************************
@endverbatim
@par Example Description
UART transmission (transmit/receive) in DMA mode
between two boards.
Board: STM32F722ZE-Nucleo (embeds a STM32F722ZE device)
Tx Pin: PC6 connected to pin 1 on CN7 connector.
Rx Pin: PC7 connected to pin 11 on CN7 connector.
_________________________ _________________________
| ______________| |______________ |
| |USART | | USART| |
| | | | | |
| | TX |_____________________| RX | |
| | | | | |
| | | | | |
| | | | | |
| | RX |_____________________| TX | |
| | | | | |
| |______________| |______________| |
| | | |
| GND|_____________________|GND |
|_STM32_Board 1___________| |_STM32_Board 2___________|
Two identical boards are connected as shown on the picture above.
Board 1: transmitting then receiving board
Board 2: receiving then transmitting board
The user presses the User push-button on board 1.
Then, board 1 sends in DMA mode a message to board 2 that sends it back to
board 1 in DMA mode as well.
Finally, board 1 and 2 compare the received message to that sent.
If the messages are the same, the test passes.
WARNING: as both boards do not behave the same way, "TRANSMITTER_BOARD" compilation
switch is defined in /Src/main.c and must be enabled
at compilation time before loading the executable in the board that first transmits
then receives.
The receiving then transmitting board needs to be loaded with an executable
software obtained with TRANSMITTER_BOARD disabled.
STM32F722ZE-Nucleo board LEDs are used to monitor the transfer status:
- While board 1 is waiting for the user to press the User push-button, its LED_GREEN is blinking rapidly (100 ms period).
- While board 2 is waiting for the message from board 1, its LED_GREEN is emitting a couple of flashes every half-second.
- After the transmission/reception processes begin LED_BLUE is turned on on.
- Once the transmission/reception processes are completed LED_BLUE is turned off on.
- When the test passes, LED_GREEN on both boards is turned on, otherwise the test has failed.
- If there is an initialization or transfer error, LED_RED is turned on.
At the beginning of the main program the HAL_Init() function is called to reset
all the peripherals, initialize the Flash interface and the systick.
Then the SystemClock_Config() function is used to configure the system
clock (SYSCLK) to run at 216 MHz.
The UART is configured as follows:
- BaudRate = 9600 baud
- Word Length = 8 bits (8 data bits, no parity bit)
- One Stop Bit
- No parity
- Hardware flow control disabled (RTS and CTS signals)
- Reception and transmission are enabled in the time
@note USARTx/UARTx instance used and associated resources can be updated in "main.h"
file depending hardware configuration used.
@note When the parity is enabled, the computed parity is inserted at the MSB
position of the transmitted data.
@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 application need to ensure that the SysTick time base is always set to 1 millisecond
to have correct HAL operation.
@par Keywords
Connectivity, UART, Baud rate, RS-232, Full-duplex, DMA, Parity, Stop bit, Transmission, Reception,
@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,
<20><><A0><A0><A0>then it is highly recommended to enable the CPU cache and maintain its coherence at application level.
<0A><><A0><A0><A0><A0>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).
@Note It is recommended to enable the cache and maintain its coherence, but depending on the use case
<0A><><A0><A0><A0> It is also possible to configure the MPU as "Write through", to guarantee the write access coherence.
<0A><><A0><A0><A0><A0>In that case, the MPU must be configured as Cacheable/Bufferable/Not Shareable.
<0A><><A0><A0><A0><A0>Even though the user must manage the cache coherence for read accesses.
<0A><><A0><A0><A0><A0>Please refer to the AN4838 <20>Managing memory protection unit (MPU) in STM32 MCUs<55>
<0A><><A0><A0><A0><A0>Please refer to the AN4839 <20>Level 1 cache on STM32F7 Series<65>
@par Directory contents
- UART/UART_TwoBoards_ComDMA/Inc/stm32f7xx_hal_conf.h HAL configuration file
- UART/UART_TwoBoards_ComDMA/Inc/stm32f7xx_it.h DMA interrupt handlers header file
- UART/UART_TwoBoards_ComDMA/Inc/main.h Header for main.c module
- UART/UART_TwoBoards_ComDMA/Src/stm32f7xx_it.c DMA interrupt handlers
- UART/UART_TwoBoards_ComDMA/Src/main.c Main program
- UART/UART_TwoBoards_ComDMA/Src/stm32f7xx_hal_msp.c HAL MSP module
- UART/UART_TwoBoards_ComDMA/Src/system_stm32f7xx.c STM32F7xx system source file
@par Hardware and Software environment
- This example runs on STM32F722xx/STM32F723xx/STM32F732xx/STM32F733xx devices.
- This example has been tested with two STM32F722ZE-Nucleo boards embedding
a STM32F722ZE device and can be easily tailored to any other supported device
and development board.
- STM32F722ZE-Nucleo set-up
- Connect a wire between 1st board PC6 pin (Uart Tx) and 2nd board PC7 pin (Uart Rx)
- Connect a wire between 1st board PC7 pin (Uart Rx) and 2nd board PC6 pin (Uart Tx)
- Connect 1st board GND to 2nd Board GND
@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
*/
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