/**
@page TIM_TimeBase Time Base example
@verbatim
******************************************************************************
* @file TIM/TIM_TimeBase/readme.txt
* @author MCD Application Team
* @brief Description of the TIM Time Base 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
This example shows how to configure the TIM peripheral to generate a time base of
one second with the corresponding Interrupt request.
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.
The SystemClock_Config() function is used to configure the system clock for STM32WL55JCIx Devices :
The CPU at 48 MHz
In this example TIM2 input clock (TIM2CLK) is set to APB1 clock (PCLK1),
since APB1 prescaler is equal to 1.
TIM2CLK = PCLK1
PCLK1 = HCLK
=> TIM2CLK = HCLK = SystemCoreClock
To get TIM2 counter clock at 10 KHz, the Prescaler is computed as following:
Prescaler = (TIM2CLK / TIM2 counter clock) - 1
Prescaler = (SystemCoreClock /10 KHz) - 1
SystemCoreClock is set to 48 MHz for STM32WLxx Devices.
The TIM2 ARR register value is equal to 10000 - 1,
Update rate = TIM2 counter clock / (Period + 1) = 1 Hz,
So the TIM2 generates an interrupt each 1 s
When the counter value reaches the auto-reload register value, the TIM update
interrupt is generated and, in the handler routine, pin PB.09 (connected to LED2 on board NUCLEO-WL55JC RevC)
is toggled. So led blinks at the following frequency: 0.5Hz.
In case of error, LED3 is turned ON.
@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 This example needs to ensure that the SysTick time base is always set to 1 millisecond
to have correct HAL operation.
@par Keywords
Timer, TIM, time base , Interrupt, Clock source
@par Directory contents
- TIM/TIM_TimeBase/Inc/stm32wlxx_nucleo_conf.h BSP configuration file
- TIM/TIM_TimeBase/Inc/stm32wlxx_hal_conf.h HAL configuration file
- TIM/TIM_TimeBase/Inc/stm32wlxx_it.h Interrupt handlers header file
- TIM/TIM_TimeBase/Inc/main.h Header for main.c module
- TIM/TIM_TimeBase/Src/stm32wlxx_it.c Interrupt handlers
- TIM/TIM_TimeBase/Src/main.c Main program
- TIM/TIM_TimeBase/Src/stm32wlxx_hal_msp.c HAL MSP file
- TIM/TIM_TimeBase/Src/system_stm32wlxx.c STM32WLxx system source file
@par Hardware and Software environment
- This example runs on STM32WL55JCIx devices.
- In this example, the clock is set to 48 MHz.
- This example has been tested with STMicroelectronics NUCLEO-WL55JC RevC
board and can be easily tailored to any other supported device
and development board.
- NUCLEO-WL55JC RevC Set-up
- Use LED2 connected to PB.09 pin (pin 26 in CN10 connector) and connect it on an oscilloscope
to show the time base signal.
@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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