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89 lines
3.5 KiB
Plaintext
89 lines
3.5 KiB
Plaintext
/**
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@page TIM_TimeBase Time Base example
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@verbatim
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******************** (C) COPYRIGHT 2017 STMicroelectronics *******************
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* @file TIM/TIM_TimeBase/readme.txt
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* @author MCD Application Team
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* @brief Description of the TIM Time Base example
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******************************************************************************
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* @attention
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*
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* Copyright (c) 2017 STMicroelectronics.
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* All rights reserved.
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*
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* This software is licensed under terms that can be found in the LICENSE file
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* in the root directory of this software component.
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* If no LICENSE file comes with this software, it is provided AS-IS.
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*
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******************************************************************************
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@endverbatim
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@par Example Description
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This example shows how to configure the TIM peripheral to generate a time base of
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one second with the corresponding Interrupt request.
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In this example TIM3 input clock (TIM3CLK) is set to 2 * APB1 clock (PCLK1),
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since APB1 prescaler is different from 1.
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TIM3CLK = 2 * PCLK1
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PCLK1 = HCLK / 4
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=> TIM3CLK = HCLK / 2 = SystemCoreClock /2 (Hz)
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To get TIM3 counter clock at 10 KHz, the Prescaler is computed as following:
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- Prescaler = (TIM3CLK / TIM3 counter clock) - 1
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SystemCoreClock is set to 168MHz for STM32F4xx Devices.
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The TIM3 ARR register value is equal to 10000 - 1,
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Update rate = TIM3 counter clock / (Period + 1) = 1 Hz,
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So the TIM3 generates an interrupt each 1 s
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When the counter value reaches the auto-reload register value, the TIM updates
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interrupt is generated and, in the handler routine, PD.12 is toggled at the following frequency: 0.5Hz.
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@note Care must be taken when using HAL_Delay(), this function provides accurate delay (in milliseconds)
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based on variable incremented in SysTick ISR. This implies that if HAL_Delay() is called from
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a peripheral ISR process, then the SysTick interrupt must have higher priority (numerically lower)
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than the peripheral interrupt. Otherwise the caller ISR process will be blocked.
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To change the SysTick interrupt priority you have to use HAL_NVIC_SetPriority() function.
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@note The application needs to ensure that the SysTick time base is always set to 1 millisecond
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to have correct HAL operation.
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@par Keywords
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Timer, TIM, Time Base, Interrupt, Clock source
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@par Directory contents
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- TIM/TIM_TimeBase/Inc/stm32f4xx_hal_conf.h HAL configuration file
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- TIM/TIM_TimeBase/Inc/stm32f4xx_it.h Interrupt handlers header file
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- TIM/TIM_TimeBase/Inc/main.h Main program header file
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- TIM/TIM_TimeBase/Src/stm32f4xx_it.c Interrupt handlers
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- TIM/TIM_TimeBase/Src/main.c Main program
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- TIM/TIM_TimeBase/Src/stm32f4xx_hal_msp.c HAL MSP module
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- TIM/TIM_TimeBase/Src/system_stm32f4xx.c STM32F4xx system clock configuration file
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@par Hardware and Software environment
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- This example runs on STM32F407xx devices.
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- This example has been tested with STM32F4-Discovery RevB & RevC board (MB997) and can be
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easily tailored to any other supported device and development board.
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- STM32F4-Discovery RevB & RevCboard (MB997) Set-up
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- Use LED4(GREEN) connected respectively PD.12 pin and connect them on an oscilloscope to show
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the different Time Base signals.
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@par How to use it ?
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In order to make the program work, you must do the following :
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- Open your preferred toolchain
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- Rebuild all files and load your image into target memory
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- Run the example
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*/
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