STM32F103R6 SysTick And Digital Clock Example

SysTick is a timer bases on timer interrupt that regularly update its value. We can use it for generating timing delay. It run on background allowing the main program loop to do other tasks. In this example I will use this feature to create a 4-digit digital clock. It shows only MM:SS.

 

Simulating Program

It's free running as it's just an introductory example. Display type is common anode. It's just a simulation model in Proteus VSM. I'm not sure about the read physical device. Device's clock rate is 8MHz.

Device Configuration

I use STM32 HAL driver and code configuration wizard to write this program.

/* USER CODE BEGIN Header */
/**
  ******************************************************************************
  * @file           : main.c
  * @brief          : Main program body
  ******************************************************************************
  * @attention
  *
  * <h2><center>&copy; Copyright (c) 2022 STMicroelectronics.
  * All rights reserved.</center></h2>
  *
  * 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
  *
  ******************************************************************************
  */
/* USER CODE END Header */
/* Includes ------------------------------------------------------------------*/
#include "main.h"
 
 
/* Private function prototypes -----------------------------------------------*/
void SystemClock_Config(void);
static void MX_GPIO_Init(void);
/* USER CODE BEGIN PFP */
 
void ssdAssign(unsigned char _data);
 
const char dAnode[10]   = {0xC0,0xF9,0xA4,0xB0,0x99,0x92,0x82,0xF8,0x80,0x90};
unsigned char mark = 0x7F;
volatile unsigned int secondCnt=0,msCnt=0,msSsd=0,minuteCnt=0;
 
/**
  * @brief  The application entry point.
  * @retval int
  */
int main(void)
{
 
  /* Reset of all peripherals, Initializes the Flash interface and the Systick. */
  HAL_Init();
 
  /* Configure the system clock */
  SystemClock_Config();
 
  /* Initialize all configured peripherals */
  MX_GPIO_Init();
 
  /*SysTick Configuration*/
    SystemCoreClockUpdate();
    /*Generate interrupt for 100 us*/
    SysTick_Config(SystemCoreClock/10000);
    SysTick ->CTRL=0;
    SysTick ->VAL=0;
    SysTick ->CTRL=(SysTick_CTRL_TICKINT_Msk		//Enable SysTick Exception
  		  	  	  |SysTick_CTRL_ENABLE_Msk		//Enable SysTick system timer
  				  |SysTick_CTRL_CLKSOURCE_Msk); //Use process clock source
 
  /* USER CODE BEGIN WHILE */
  while (1)
  {
	  switch(msSsd){
	  	  	  case 0:
	  	  		  	  GPIOB ->ODR = dAnode[secondCnt/10]&mark;
	  	  		  	  GPIOB ->ODR |= GPIO_ODR_ODR13;
	  	  		  	  break;
 
	  	  	  case 5:
	  	  		  	  GPIOB ->ODR = dAnode[secondCnt%10]&mark;
	  	  		  	  GPIOB ->ODR |= GPIO_ODR_ODR12;
	  	  		  	  break;
 
	  	  	  case 10:
	  	  		  	  GPIOB ->ODR = dAnode[minuteCnt/10]&mark;
	  	  		  	  GPIOB ->ODR |= GPIO_ODR_ODR15;
	  	  		  	  break;
 
	  	  	  case 15:
	  	  		  	  GPIOB ->ODR = dAnode[minuteCnt%10]&mark;
	  	  		  	  GPIOB ->ODR |= GPIO_ODR_ODR14;
	  	  		  	  break;
 
	  	  }
  }
  /* USER CODE END 3 */
}
 
void SysTick_Handler(void)
{
 
  HAL_IncTick();
 
  if(uwTick>=10){
	  msCnt+=1;
	  msSsd+=1;
	  uwTick=0;
  }
 
  if(msCnt>=500){
	  secondCnt+=1;
	  msCnt=0;
	  mark^=0x80;
  }
 
  if(secondCnt>=60){
	  secondCnt=0;
	  minuteCnt+=1;
  }
 
  if(minuteCnt>=60) minuteCnt=0;
 
  if(msSsd>20) msSsd=0;
 
 
}
 
/**
  * @brief System Clock Configuration
  * @retval None
  */
void SystemClock_Config(void)
{
  RCC_OscInitTypeDef RCC_OscInitStruct = {0};
  RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};
 
  /** Initializes the RCC Oscillators according to the specified parameters
  * in the RCC_OscInitTypeDef structure.
  */
  RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSI;
  RCC_OscInitStruct.HSIState = RCC_HSI_ON;
  RCC_OscInitStruct.HSICalibrationValue = RCC_HSICALIBRATION_DEFAULT;
  RCC_OscInitStruct.PLL.PLLState = RCC_PLL_NONE;
  if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
  {
    Error_Handler();
  }
  /** Initializes the CPU, AHB and APB buses clocks
  */
  RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_SYSCLK
                              |RCC_CLOCKTYPE_PCLK1|RCC_CLOCKTYPE_PCLK2;
  RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_HSI;
  RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
  RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV1;
  RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;
 
  if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_0) != HAL_OK)
  {
    Error_Handler();
  }
}
 
/**
  * @brief GPIO Initialization Function
  * @param None
  * @retval None
  */
static void MX_GPIO_Init(void)
{
  GPIO_InitTypeDef GPIO_InitStruct = {0};
 
  /* GPIO Ports Clock Enable */
  __HAL_RCC_GPIOB_CLK_ENABLE();
  __HAL_RCC_GPIOA_CLK_ENABLE();
 
  /*Configure GPIO pin Output Level */
  HAL_GPIO_WritePin(GPIOB, GPIO_PIN_0|GPIO_PIN_1|GPIO_PIN_2|GPIO_PIN_12
                          |GPIO_PIN_13|GPIO_PIN_14|GPIO_PIN_15|GPIO_PIN_3
                          |GPIO_PIN_4|GPIO_PIN_5|GPIO_PIN_6|GPIO_PIN_7, GPIO_PIN_RESET);
 
  /*Configure GPIO pins : PB0 PB1 PB2 PB12
                           PB13 PB14 PB15 PB3
                           PB4 PB5 PB6 PB7 */
  GPIO_InitStruct.Pin = GPIO_PIN_0|GPIO_PIN_1|GPIO_PIN_2|GPIO_PIN_12
                          |GPIO_PIN_13|GPIO_PIN_14|GPIO_PIN_15|GPIO_PIN_3
                          |GPIO_PIN_4|GPIO_PIN_5|GPIO_PIN_6|GPIO_PIN_7;
  GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
  GPIO_InitStruct.Pull = GPIO_NOPULL;
  GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_HIGH;
  HAL_GPIO_Init(GPIOB, &GPIO_InitStruct);
 
}
 
/* USER CODE BEGIN 4 */
 
/* USER CODE END 4 */
 
/**
  * @brief  This function is executed in case of error occurrence.
  * @retval None
  */
void Error_Handler(void)
{
  /* USER CODE BEGIN Error_Handler_Debug */
  /* User can add his own implementation to report the HAL error return state */
  __disable_irq();
  while (1)
  {
  }
  /* USER CODE END Error_Handler_Debug */
}
 
#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 CODE BEGIN 6 */
  /* 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) */
  /* USER CODE END 6 */
}
#endif /* USE_FULL_ASSERT */
 
/************************ (C) COPYRIGHT STMicroelectronics *****END OF FILE****/
 

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