/**
@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.
******************************************************************************
*
* Copyright (c) 2020 STMicroelectronics. All rights reserved.
*
* 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 Example Description
UART transmission (transmit/receive) in DMA mode
between two boards.
Board: NUCLEO-WL55JC RevC (embeds a STM32WL55JCIx device)
Tx Pin: PB.06 (Arduino connector CN9 pin 2)
Rx Pin: PB.07 (Arduino connector CN9 pin 1)
_________________________ _________________________
| ______________| |______________ |
| |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 (B1) 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.
NUCLEO-WL55JC RevC board LEDs are used to monitor the transfer status:
- While board 1 is waiting for the user to press the User push-button (B1), its LED1 is
blinking rapidly (100 ms period).
- While board 2 is waiting for the message from board 1, its LED1 is emitting
a couple of flashes every half-second.
- When the test passes, LED1 is turned on.
- If there is an initialization or transfer error, LED3 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 48 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 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 needs to ensure that the SysTick time base is always set to 1 millisecond
to have correct HAL operation.
@par Keywords
Connectivity, UART/USART, baud rate, RS-232, full-duplex, DMA, parity, stop bit,
Transmitter, Receiver, Asynchronous
@par Directory contents
- UART/UART_TwoBoards_ComDMA/Inc/stm32wlxx_nucleo_conf.h BSP configuration file
- UART/UART_TwoBoards_ComDMA/Inc/stm32wlxx_hal_conf.h HAL configuration file
- UART/UART_TwoBoards_ComDMA/Inc/stm32wlxx_it.h DMA interrupt handlers header file
- UART/UART_TwoBoards_ComDMA/Inc/main.h Header for main.c module
- UART/UART_TwoBoards_ComDMA/Src/stm32wlxx_it.c DMA interrupt handlers
- UART/UART_TwoBoards_ComDMA/Src/main.c Main program
- UART/UART_TwoBoards_ComDMA/Src/stm32wlxx_hal_msp.c HAL MSP module
- UART/UART_TwoBoards_ComDMA/Src/system_stm32wlxx.c STM32WLxx system source file
@par Hardware and Software environment
- This example runs on STM32WL55JCIx devices.
- This example has been tested with two NUCLEO-WL55JC RevC boards embedding
a STM32WL55JCIx device and can be easily tailored to any other supported device
and development board.
- NUCLEO-WL55JC RevC set-up
- Connect a wire between 1st board PB6 pin (Uart Tx) and 2nd board PB7 pin (Uart Rx)
- Connect a wire between 1st board PB7 pin (Uart Rx) and 2nd board PB6 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
* <h3><center>© COPYRIGHT STMicroelectronics</center></h3>
*/
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