STM32F103C8T6 Blue Pill SysTick and Multiplexing Display Example

SysTick is a timer inside the STM32 ARM processor. We can use this time to schedule any task in microcontroller program. It's simple to use in STM32Cube IDE. In this example, I use this timer to drive a three-digit multiplexing display.

Running program on breadboard

It will count up to 999 before it rolls down to zero. The display type is common cathode. I use one ULN2003 transistor drivers chip due to ease of use.

Wiring diagram

STM32CubeIDE is a good choice for me because it's free to use. 

/* 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 */
 
const char dCathode[10]={0x3F,0x06,0x5B,0x4F,0x66,0x6D,0x7D,0x07,0x7F,0x6F};
volatile unsigned int msCnt=0, msSsd=0,pressCnt=0;
 
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 every 100 us*/
  SysTick_Config(SystemCoreClock/10000);
  SysTick ->CTRL=0;
  SysTick ->VAL =0;
  SysTick ->CTRL = (SysTick_CTRL_TICKINT_Msk
  		  	  	  	|SysTick_CTRL_ENABLE_Msk
  					|SysTick_CTRL_CLKSOURCE_Msk);
  while (1)
  {
	  /*Multiplex Display Process*/
	  	  switch(msSsd){
	  	  	  case 0:
	  	  		  GPIOA -> ODR = dCathode[pressCnt/100]<<1;
	  	  		  GPIOC -> ODR = GPIO_ODR_ODR13;
	  	  		  break;
 
	  	  	  case 5:
	  	  		  GPIOA -> ODR = dCathode[(pressCnt%100)/10]<<1;
	  	  		  GPIOC -> ODR = GPIO_ODR_ODR14;
	  	  		  break;
 
	  	  	  case 15:
	  	  		  GPIOA -> ODR = dCathode[pressCnt%10]<<1;
	  	  		  GPIOC -> ODR = GPIO_ODR_ODR15;
	  	  		  break;
	  	  }
  }
}
 
void SysTick_Handler(void)
{
 
  HAL_IncTick();
 
  if(uwTick>=10){
  	  msCnt+=1;
  	  msSsd+=1;
  	  uwTick=0;
    }
 
    if(msCnt>=300) {
    	pressCnt+=1;
    	msCnt=0;
    }
    if(msSsd>20) msSsd=0;
    if(pressCnt>999) pressCnt=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_GPIOC_CLK_ENABLE();
  __HAL_RCC_GPIOA_CLK_ENABLE();
 
  /*Configure GPIO pin Output Level */
  HAL_GPIO_WritePin(GPIOC, GPIO_PIN_13|GPIO_PIN_14|GPIO_PIN_15, GPIO_PIN_RESET);
 
  /*Configure GPIO pin Output Level */
  HAL_GPIO_WritePin(GPIOA, GPIO_PIN_0|GPIO_PIN_1|GPIO_PIN_2|GPIO_PIN_4|GPIO_PIN_3
                          |GPIO_PIN_5|GPIO_PIN_6|GPIO_PIN_7|GPIO_PIN_8, GPIO_PIN_RESET);
 
  /*Configure GPIO pins : PC13 PC14 PC15 */
  GPIO_InitStruct.Pin = GPIO_PIN_13|GPIO_PIN_14|GPIO_PIN_15;
  GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
  GPIO_InitStruct.Pull = GPIO_NOPULL;
  GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_HIGH;
  HAL_GPIO_Init(GPIOC, &GPIO_InitStruct);
 
  /*Configure GPIO pins : PA0 PA1 PA2 PA4
                           PA5 PA6 PA7 */
  GPIO_InitStruct.Pin = GPIO_PIN_0|GPIO_PIN_1|GPIO_PIN_2|GPIO_PIN_4|GPIO_PIN_3
                          |GPIO_PIN_5|GPIO_PIN_6|GPIO_PIN_7|GPIO_PIN_8;
  GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
  GPIO_InitStruct.Pull = GPIO_PULLUP;
  GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_HIGH;
  HAL_GPIO_Init(GPIOA, &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****/
 

 

Click here to download its source file. For other similar posts please check,

1. Getting Started With STM32F103C8T6 Module with STM32CubeIDE
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3.  STM32F103C8T6 Blue Pill Switch And Multiplexing Display Interface Using SysTick
4.  STM32F103C8T6 Blue Pill SysTick LED Blinking