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/**
******************************************************************************
* @file TIM/TIM_PrescalerSelection/Src/main.c
* @author MCD Application Team
* @brief This sample code shows how to use STM32F4xx TIM HAL API to generate
* 1 signal in PWM.
******************************************************************************
* @attention
*
* Copyright (c) 2017 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.
*
******************************************************************************
*/
/* Includes ------------------------------------------------------------------*/
#include "main.h"
/** @addtogroup STM32F4xx_HAL_Examples
* @{
*/
/** @addtogroup TIM_PrescalerSelection
* @{
*/
/* Private typedef -----------------------------------------------------------*/
#define PERIOD_VALUE (uint32_t)(1800 - 1) /* Period Value */
#define PULSE1_VALUE (uint32_t)(900 - 1) /* Capture Compare 1 Value */
/* Private define ------------------------------------------------------------*/
/* Private macro -------------------------------------------------------------*/
/* Private variables ---------------------------------------------------------*/
/* Timer handler declaration */
TIM_HandleTypeDef TimHandle;
/* Timer Output Compare Configuration Structure declaration */
TIM_OC_InitTypeDef sConfig;
/* Counter Prescaler value */
uint32_t uhPrescalerValue = 0;
/* Private function prototypes -----------------------------------------------*/
static void SystemClock_Config(void);
static void Error_Handler(void);
/* Private functions ---------------------------------------------------------*/
/**
* @brief Main program.
* @param None
* @retval None
*/
int main(void)
{
/* STM32F4xx HAL library initialization:
- Configure the Flash prefetch, instruction and Data caches
- Systick timer is configured by default as source of time base, but user
can eventually implement his proper time base source (a general purpose
timer for example or other time source), keeping in mind that Time base
duration should be kept 1ms since PPP_TIMEOUT_VALUEs are defined and
handled in milliseconds basis.
- Set NVIC Group Priority to 4
- Low Level Initialization: global MSP (MCU Support Package) initialization
*/
HAL_Init();
/* Configure LED3 */
BSP_LED_Init(LED3);
/* Configure the system clock to 180 MHz */
SystemClock_Config();
/* Compute the prescaler value to have TIM3 counter clock equal to 36000000 Hz */
uhPrescalerValue = (uint32_t)(SystemCoreClock / 36000000) - 1;
/*##-1- Configure the TIM peripheral #######################################*/
/* -----------------------------------------------------------------------
TIM3 Configuration: generate 1 PWM signal with clock prescaler selection feature activated using __HAL_RCC_TIMCLKPRESCALER()
which allow to double the output frequency.
In this example TIM3 input clock (TIM3CLK) is set to 4 * APB1 clock (PCLK1), since
Timer clock prescalers selection activated (TIMPRE bit from RCC_DCKCFGR register is set).
TIM3CLK = 4 * PCLK1
PCLK1 = HCLK / 4
=> TIM3CLK = HCLK = SystemCoreClock
For TIM3CLK equal to SystemCoreClock and prescaler equal to (5 - 1), TIM3 counter clock
is computed as follows:
TIM3 counter clock = TIM3CLK / (Prescaler + 1)
= SystemCoreClock / (Prescaler + 1)
= 36MHz
For ARR equal to (1800 - 1), the TIM3 output clock is computed as follows:
TIM3 output clock = TIM3 counter clock / (ARR + 1)
= 20KHZ
The TIM3 CCR1 register value is equal to 900, so the TIM3 Channel 1 generates a
PWM signal with a frequency equal to 20 KHz and a duty cycle equal to 50%:
TIM3 Channel1 duty cycle = (TIM3_CCR1/ TIM3_ARR + 1)* 100 = 50%
Note:
SystemCoreClock variable holds HCLK frequency and is defined in system_stm32f4xx.c file.
Each time the core clock (HCLK) changes, user had to update SystemCoreClock
variable value. Otherwise, any configuration based on this variable will be incorrect.
This variable is updated in three ways:
1) by calling CMSIS function SystemCoreClockUpdate()
2) by calling HAL API function HAL_RCC_GetSysClockFreq()
3) each time HAL_RCC_ClockConfig() is called to configure the system clock frequency
----------------------------------------------------------------------- */
/* Timer clock prescalers selection activation */
__HAL_RCC_TIMCLKPRESCALER(RCC_TIMPRES_ACTIVATED);
/* Initialize TIMx peripheral as follows:
+ Prescaler = (SystemCoreClock / 36000000) - 1
+ Period = (1800 - 1)
+ ClockDivision = 0
+ Counter direction = Up
*/
TimHandle.Instance = TIMx;
TimHandle.Init.Prescaler = uhPrescalerValue;
TimHandle.Init.Period = PERIOD_VALUE;
TimHandle.Init.ClockDivision = 0;
TimHandle.Init.CounterMode = TIM_COUNTERMODE_UP;
TimHandle.Init.RepetitionCounter = 0;
TimHandle.Init.AutoReloadPreload = TIM_AUTORELOAD_PRELOAD_DISABLE;
if (HAL_TIM_PWM_Init(&TimHandle) != HAL_OK)
{
/* Initialization Error */
Error_Handler();
}
/*##-2- Configure the PWM channels #########################################*/
/* Common configuration for all channels */
sConfig.OCMode = TIM_OCMODE_PWM1;
sConfig.OCPolarity = TIM_OCPOLARITY_HIGH;
sConfig.OCFastMode = TIM_OCFAST_DISABLE;
sConfig.OCNPolarity = TIM_OCNPOLARITY_HIGH;
sConfig.OCNIdleState = TIM_OCNIDLESTATE_RESET;
sConfig.OCIdleState = TIM_OCIDLESTATE_RESET;
/* Set the pulse value for channel 1 */
sConfig.Pulse = PULSE1_VALUE;
if (HAL_TIM_PWM_ConfigChannel(&TimHandle, &sConfig, TIM_CHANNEL_1) != HAL_OK)
{
/* Configuration Error */
Error_Handler();
}
/*##-3- Start PWM signals generation #######################################*/
/* Start channel 1 */
if (HAL_TIM_PWM_Start(&TimHandle, TIM_CHANNEL_1) != HAL_OK)
{
/* PWM Generation Error */
Error_Handler();
}
/* Start channel 2 */
if (HAL_TIM_PWM_Start(&TimHandle, TIM_CHANNEL_2) != HAL_OK)
{
/* PWM Generation Error */
Error_Handler();
}
/* Start channel 3 */
if (HAL_TIM_PWM_Start(&TimHandle, TIM_CHANNEL_3) != HAL_OK)
{
/* PWM generation Error */
Error_Handler();
}
/* Start channel 4 */
if (HAL_TIM_PWM_Start(&TimHandle, TIM_CHANNEL_4) != HAL_OK)
{
/* PWM generation Error */
Error_Handler();
}
while (1)
{
}
}
/**
* @brief This function is executed in case of error occurrence.
* @param None
* @retval None
*/
static void Error_Handler(void)
{
/* Turn LED3 on */
BSP_LED_On(LED3);
while (1)
{
}
}
/**
* @brief System Clock Configuration
* The system Clock is configured as follow :
* System Clock source = PLL (HSE)
* SYSCLK(Hz) = 180000000
* HCLK(Hz) = 180000000
* AHB Prescaler = 1
* APB1 Prescaler = 4
* APB2 Prescaler = 2
* HSE Frequency(Hz) = 25000000
* PLL_M = 25
* PLL_N = 360
* PLL_P = 2
* PLL_Q = 7
* PLL_R = 6
* VDD(V) = 3.3
* Main regulator output voltage = Scale1 mode
* Flash Latency(WS) = 5
* @param None
* @retval None
*/
static void SystemClock_Config(void)
{
RCC_ClkInitTypeDef RCC_ClkInitStruct;
RCC_OscInitTypeDef RCC_OscInitStruct;
HAL_StatusTypeDef ret = HAL_OK;
/* Enable Power Control clock */
__HAL_RCC_PWR_CLK_ENABLE();
/* The voltage scaling allows optimizing the power consumption when the device is
clocked below the maximum system frequency, to update the voltage scaling value
regarding system frequency refer to product datasheet. */
__HAL_PWR_VOLTAGESCALING_CONFIG(PWR_REGULATOR_VOLTAGE_SCALE1);
/* Enable HSE Oscillator and activate PLL with HSE as source */
RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSE;
RCC_OscInitStruct.HSEState = RCC_HSE_ON;
RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSE;
RCC_OscInitStruct.PLL.PLLM = 25;
RCC_OscInitStruct.PLL.PLLN = 360;
RCC_OscInitStruct.PLL.PLLP = RCC_PLLP_DIV2;
RCC_OscInitStruct.PLL.PLLQ = 7;
RCC_OscInitStruct.PLL.PLLR = 6;
ret = HAL_RCC_OscConfig(&RCC_OscInitStruct);
if(ret != HAL_OK)
{
while(1) { ; }
}
/* Activate the OverDrive to reach the 180 MHz Frequency */
ret = HAL_PWREx_EnableOverDrive();
if(ret != HAL_OK)
{
while(1) { ; }
}
/* Select PLL as system clock source and configure the HCLK, PCLK1 and PCLK2 clocks dividers */
RCC_ClkInitStruct.ClockType = (RCC_CLOCKTYPE_SYSCLK | RCC_CLOCKTYPE_HCLK | RCC_CLOCKTYPE_PCLK1 | RCC_CLOCKTYPE_PCLK2);
RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV4;
RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV2;
ret = HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_5);
if(ret != HAL_OK)
{
while(1) { ; }
}
}
#ifdef USE_FULL_ASSERT
/**
* @brief Reports the name of the source file and the source line number
* where the assert_param error has occurred.
* @param file: pointer to the source file name
* @param line: assert_param error line source number
* @retval None
*/
void assert_failed(uint8_t *file, uint32_t line)
{
/* User can add his own implementation to report the file name and line number,
ex: printf("Wrong parameters value: file %s on line %d\r\n", file, line) */
/* Infinite loop */
while (1)
{
}
}
#endif
/**
* @}
*/
/**
* @}
*/
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