/**
@page UART_WakeUpFromStop UART Wake up from Stop mode example
@verbatim
******************** (C) COPYRIGHT 2016 STMicroelectronics *******************
* @file UART/UART_WakeUpFromStop/readme.txt
* @author MCD Application Team
* @brief Description of the UART-triggered MCU wake-up from STOP mode.
******************************************************************************
* @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
Configuration of an UART to wake up the MCU from STOP mode
when a given stimulus is received.
Board: STM32F072RB-Nucleo RevC (embeds a STM32F072RBT6 device)
Tx Pin: PA.09
Rx Pin: PA.10
_________________________ _________________________
| ______________| |______________ |
| |USART | | USART| |
| | | | | |
| | TX |_____________________| RX | |
| | | | | |
| | | | | |
| | | | | |
| | RX |_____________________| TX | |
| | | | | |
| |______________| |______________| |
| | | |
| | | |
| STM32 Board 1 | | STM32 Board 2 |
| (follows a sequence of | | (sends stimuli to wake |
| RUN/STOP modes) | | up STM32 Board 1) |
|_________________________| |_________________________|
Board 1 enters STOP mode and is awoken by Board 2 which sends
the proper data to wake up the board 1 MCU.
When the proper wake-up event is recognized, the WUF interrupt is triggered which wakes
up board 1.
To confirm its wake up, board 1 sends a confirmation message to board 2 which
checks it is the expected message.
This cycle is repeated 4 times to verify 4 different events
1<>) wake-up by RXNE flag rising
2<>) wake-up by Start Bit detection
3<>) wake-up by 7-bit long address match
4<>) wake-up by 4-bit long address match
WARNING: as both boards do not behave the same way, "BOARD_IN_STOP_MODE"
compilation switch is defined in UART/UART_WakeUpFromStop/Src/main.c and must be
enabled at compilation time before loading the executable in board 1 (that which
is set in STOP mode).
The stimuli-transmitting board (board 2) needs to be loaded with an executable
software obtained with BOARD_IN_STOP_MODE disabled.
At the very beginning, board 1 LED2 is ON then is turned off.
This means that board 1 has entered STOP mode.
Parallelly, board 2 LED2 is quickly blinking (100 ms period). The user has
just to wait for board 1 LED2 to be turned off then to press board 2 USER
push-button to send the first wake-up stimulus to board 1.
This starts the test sequence and no more action is required from the user
(a single USER push-button press is needed to start the full 4 wake-up events
test sequence).
Board 1 LED2 behavior as described below allows to follow the
test progress:
ON ____ _______ _______ _______ ____
| | | | | | | |
OFF |________| |________| |________| |________|
Enter Exit Enter Exit Enter Exit Enter Exit
Stop Stop Stop Stop Stop Stop Stop Stop
Mode Mode Mode Mode Mode Mode Mode Mode
(RXNE flag) (Start Bit (7-bit add. (4-bit add.
Detection) match) match)
Simultaneously, board 2 LED2 behavior shown below allows to follow the
test progress on the other side:
BLINKING
ON ****________ _______ _______ _______ ____
| | | | | | | |
OFF |________| |________| |________| |________|
USER WkUp 2nd stim WkUp 3rd stim WkUp 4th stim WkUp LED ON
button conf sent conf sent conf sent conf to mark
pushed, rcv'ed rcv'ed rcv'ed rcv'ed passed
1st stimulus test
sent
(RXNE flag) (Start Bit (7-bit add. (4-bit add.
Detection) match) match)
- If the test fails or if there is an initialization or transfer error, LED2
transmits a sequence of three dots, three dashes, three dots.
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
- Parity none
- Hardware flow control disabled (RTS and CTS signals)
@note USARTx/UARTx instance used and associated resources can be updated in "main.h"
file depending hardware configuration used.
@note This example can not be used in DEBUG mode due to the fact that the
Cortex-M0 core is no longer clocked during low power mode and so debugging
features are not available.
@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 Directory contents
- UART/UART_WakeUpFromStop/Inc/stm32f0xx_hal_conf.h HAL configuration file
- UART/UART_WakeUpFromStop/Inc/stm32f0xx_it.h Interrupt handlers header file
- UART/UART_WakeUpFromStop/Inc/main.h Header for main.c module
- UART/UART_WakeUpFromStop/Src/stm32f0xx_it.c Interrupt handlers
- UART/UART_WakeUpFromStop/Src/main.c Main program
- UART/UART_WakeUpFromStop/Src/stm32f0xx_hal_msp.c HAL MSP module
- UART/UART_WakeUpFromStop/Src/system_stm32f0xx.c STM32F0xx system source file
@par Hardware and Software environment
- This example runs on STM32F072RB devices.
- This example has been tested with a couple of STM32F072RB-Nucleo RevC boards embedding a
STM32F072RBT6 device and can be easily tailored to any other supported device
and development board.
- STM32F072RB-Nucleo RevC set-up
- Connect a wire between 1st board PA.09 pin (USART1 Tx) and 2nd board PA.10 pin (USART1 Rx)
- Connect a wire between 1st board PA.10 pin (USART1 Rx) and 2nd board PA.09 pin (USART1 Tx)
@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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