Posted on September 18, 2017 at 19:13 ,
,
Thanks for the reply.
If you read my post again, I state that I am using STM's example code that can be downloaded from their site. I didn't write it. STM wrote it.
Here it is in full:
/**
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, ******************************************************************************
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, * @file , , , SysTick/main.c
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, * @author , MCD Application Team
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, * @version V1.0.0
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, * @date , , , 23-March-2012
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, * @brief , , Main program body
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, ******************************************************************************
,
, * @attention
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, *
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, * <,h2>,<,center>,&,copy, COPYRIGHT 2012 STMicroelectronics<,/center>,<,/h2>,
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, *
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, * Licensed under MCD-ST Liberty SW License Agreement V2, (the 'License'),
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, * You may not use this file except in compliance with the License.
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, * You may obtain a copy of the License at:
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, *
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, * , , , , , , ,
https://community.st.com/external-link.jspa?url=http%3A%2F%2Fwww.st.com%2Fsoftware_license_agreement_liberty_v2
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, *
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, * Unless required by applicable law or agreed to in writing, software
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, * distributed under the License is distributed on an 'AS IS' BASIS,
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, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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, * See the License for the specific language governing permissions and
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, * limitations under the License.
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, *
,
, ******************************************************************************
,
, */
/* Includes ------------------------------------------------------------------*/
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♯ include 'main.h'
/** @addtogroup STM32F0_Discovery_Peripheral_Examples
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, * @{
,
, */
/** @addtogroup SysTick_Example
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, * @{
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, */
/* Private typedef -----------------------------------------------------------*/
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/* Private define ------------------------------------------------------------*/
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/* Private macro -------------------------------------------------------------*/
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/* Private variables ---------------------------------------------------------*/
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GPIO_InitTypeDef GPIO_InitStructure,
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static __IO uint32_t TimingDelay,
/* Private function prototypes -----------------------------------------------*/
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void Delay(__IO uint32_t nTime),
/* Private functions ---------------------------------------------------------*/
/**
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, * @brief , , Main program
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, * @param , None
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, * @retval None
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, */
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int main(void)
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{
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, /*!<, At this stage the microcontroller clock setting is already configured,
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, , , , , , this is done through SystemInit() function which is called from startup
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, , , , , , file (startup_stm32f0xx.s) before to branch to application main.
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, , , , , , To reconfigure the default setting of SystemInit() function, refer to
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, , , , , , system_stm32f0xx.c file
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, , , , */ , , , ,
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, , , , , ,
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, /* Initialize Leds mounted on STM32F0-discovery */
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, STM_EVAL_LEDInit(LED3),
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, STM_EVAL_LEDInit(LED4),
, /* Turn on LED3 and LED4 */
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, STM_EVAL_LEDOn(LED3),
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, STM_EVAL_LEDOn(LED4),
, /* Setup SysTick Timer for 1 msec interrupts.
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, , , , ------------------------------------------
,
, , , 1. The SysTick_Config() function is a CMSIS function which configure:
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, , , , , , - The SysTick Reload register with value passed as function parameter.
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, , , , , , - Configure the SysTick IRQ priority to the lowest value (0x0F).
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, , , , , , - Reset the SysTick Counter register.
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, , , , , , - Configure the SysTick Counter clock source to be Core Clock Source (HCLK).
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, , , , , , - Enable the SysTick Interrupt.
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, , , , , , - Start the SysTick Counter.
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, , ,
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, , , 2. You can change the SysTick Clock source to be HCLK_Div8 by calling the
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, , , , , , SysTick_CLKSourceConfig(SysTick_CLKSource_HCLK_Div8) just after the
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, , , , , , SysTick_Config() function call. The SysTick_CLKSourceConfig() is defined
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, , , , , , inside the stm32f0xx_misc.c file.
, , , 3. You can change the SysTick IRQ priority by calling the
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, , , , , , NVIC_SetPriority(SysTick_IRQn,...) just after the SysTick_Config() function
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, , , , , , call. The NVIC_SetPriority() is defined inside the core_cm0.h file.
, , , 4. To adjust the SysTick time base, use the following formula:
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, , , , , , , , , , , , , , , , , , , , , , , , , , ,
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, , , , , , , , Reload Value = SysTick Counter Clock (Hz) x , Desired Time base (s)
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, , ,
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, , , , , , - Reload Value is the parameter to be passed for SysTick_Config() function
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, , , , , , - Reload Value should not exceed 0xFFFFFF
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, , */
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, ,
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, if (SysTick_Config(SystemCoreClock / 1000))
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, {
,
, , , /* Capture error */
,
, , , while (1),
,
, }
, while (1)
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, {
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, , , /* Toggle LED4 */
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, , , STM_EVAL_LEDToggle(LED4),
, , , /* Insert 50 ms delay */
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, , , Delay(500),
, , , /* Toggle LED3 */
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, , , //STM_EVAL_LEDToggle(LED3),
, , , /* Insert 100 ms delay */
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, , , //Delay(500),
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, }
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}
/**
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, * @brief , Inserts a delay time.
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, * @param , nTime: specifies the delay time length, in milliseconds.
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, * @retval None
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, */
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void Delay(__IO uint32_t nTime)
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{
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, TimingDelay = nTime,
, while(TimingDelay != 0),
,
}
/**
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, * @brief , Decrements the TimingDelay variable.
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, * @param , None
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, * @retval None
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, */
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void TimingDelay_Decrement(void)
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{
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, if (TimingDelay != 0x00)
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, {
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, , , TimingDelay--,
,
, }
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}
♯ ifdef , USE_FULL_ASSERT
/**
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, * @brief , Reports the name of the source file and the source line number
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, * , , , , , , , , where the assert_param error has occurred.
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, * @param , file: pointer to the source file name
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, * @param , line: assert_param error line source number
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, * @retval None
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, */
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void assert_failed(uint8_t* file, uint32_t line)
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{
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, /* User can add his own implementation to report the file name and line number,
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, , , , ex: printf('Wrong parameters value: file %s on line %d\r\n', file, line) */
, /* Infinite loop */
,
, while (1)
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, {
,
, }
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}
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♯ endif
/**
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, * @}
,
, */
/**
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, * @}
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, */
/************************ (C) COPYRIGHT STMicroelectronics *****END OF FILE****/
Why does the tick seem to be slow?
