/**
@page LPUART_WakeUpFromStop LPUART Wake up from Stop mode example
@verbatim
******************************************************************************
* @file UART/LPUART_WakeUpFromStop/readme.txt
* @author MCD Application Team
* @brief Description of the LPUART-triggered MCU wake-up from STOP mode.
******************************************************************************
*
* 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
Configuration of an LPUART to wake up the MCU from Stop mode
when a given stimulus is received.
Board: NUCLEO-WL55JC RevC (embeds a STM32WL55JC device)
Tx Pin: PC1 - pin 23 of CN10 connector
Rx Pin: PC0 - pin 14 of CN10 connector
_________________________ _________________________
| ______________| |______________ |
| |LPUART | | LPUART| |
| | | | | |
| | TX |_____________________| RX | |
| | | | | |
| | | | | |
| | | | | |
| | RX |_____________________| TX | |
| | | | | |
| |______________| |______________| |
| | | |
| GND|_____________________|GND |
| | | |
| 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/LPUART_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
BUTTON_SW1 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 BUTTON_SW1 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 the maximum frequency with HSI as source of main PLL.
Additionally the HSI is enabled to demonstrate LPUART wake-up capabilities.
Each time board 1 is awoken, the system clock (SYSCLK) is restored.
The LPUART 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 This example can not be used in DEBUG mode due to the fact that the
Cortex-M4 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 needs to ensure that the SysTick time base is always set
to 1 millisecond to have correct HAL operation.
@par Keywords
Connectivity, LPUART, baud rate, RS-232, HyperTerminal, full-duplex,
Transmitter, Receiver, Asynchronous, Low Power, Wake Up
@par Directory contents
- UART/LPUART_WakeUpFromStop/Inc/stm32wlxx_nucleo_conf.h BSP configuration file
- UART/LPUART_WakeUpFromStop/Inc/stm32wlxx_hal_conf.h HAL configuration file
- UART/LPUART_WakeUpFromStop/Inc/stm32wlxx_it.h Interrupt handlers header file
- UART/LPUART_WakeUpFromStop/Inc/main.h Header for main.c module
- UART/LPUART_WakeUpFromStop/Src/stm32wlxx_it.c Interrupt handlers
- UART/LPUART_WakeUpFromStop/Src/main.c Main program
- UART/LPUART_WakeUpFromStop/Src/stm32wlxx_hal_msp.c HAL MSP module
- UART/LPUART_WakeUpFromStop/Src/system_stm32wlxx.c STM32WLxx system source file
@par Hardware and Software environment
- This example runs on STM32WL55JC devices.
- This example has been tested with a couple of NUCLEO-WL55JC RevC boards embedding a
STM32WL55JC 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 PC1 - pin 23 of CN10 connector (LPUART1 Tx)
and 2nd board PC0 - pin 14 of CN10 connector (LPUART1 Rx)
- Connect a wire between 1st board PC0 - pin 14 of CN10 connector (LPUART1 Rx)
and 2nd board PC1 - pin 23 of CN10 connector (LPUART1 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
* <h3><center>© COPYRIGHT STMicroelectronics</center></h3>
*/
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