{"id":4583,"date":"2020-06-19T12:08:29","date_gmt":"2020-06-19T10:08:29","guid":{"rendered":"https:\/\/deepbluembedded.com\/?p=4583"},"modified":"2025-02-17T15:00:54","modified_gmt":"2025-02-17T13:00:54","slug":"stm32-timer-interrupt-hal-example-timer-mode-lab","status":"publish","type":"post","link":"https:\/\/deepbluembedded.com\/stm32-timer-interrupt-hal-example-timer-mode-lab\/","title":{"rendered":"STM32 Timer Interrupt HAL Example – Timer Mode LAB"},"content":{"rendered":"\n

In this tutorial, we’ll discuss how to configure the STM32 timer module to generate timer interrupts with a couple of example projects (Timer Mode). You’ll go through step-by-step HAL example configurations to initialize all the required hardware peripherals. Then, we’ll write simple application code to test the hardware functionalities. And also we’ll see how to calculate the timer preload value to get the desired output time interval exactly. without further ado, let’s get started!<\/p>\n\n\n

Table of Contents<\/h2>\n
    \n
  1. STM32 Timer Calculation & Equation Formula<\/a>\n\n<\/li>\n
  2. STM32 Timer Interrupt Example (LAB)<\/a>\n\n<\/li>\n
  3. STM32 Timer Interrupt Example Project (Steps)<\/a>\n\n<\/li>\n
  4. STM32 Timer Interrupt Example Code in CubeMX IDE<\/a>\n\n<\/li>\n
  5. Testing The STM32 Timer Example Project<\/a>\n\n\n
  6. STM32 Timer Fine-Timing Experiment<\/a>\n\n<\/li>\n
  7. Using STM32 Timer Interrupt Calculator<\/a>\n\n<\/li>\n
  8. Wrap Up<\/a>\n<\/li><\/ol>\n\n\n
    \n\n\n

    STM32 Timer Calculation & Equation Formula<\/strong><\/h2>\n\n\n

    In this LAB, we’ll set up a general-purpose timer module to operate in timer mode. We’ll set the overflow time interval to the desired value using the equation below. And toggle an LED in the interrupt service routine (ISR) for the timer overflow event.<\/p>\n\n\n

    \n
    \"\"<\/figure>\n<\/div>\n\n\n

    <\/p>\n\n\n\n

    As you can see, the output time interval is determined by the Prescaler value, the clock frequency, and the timer auto-reload register’s value. Given that the blue pill board can run @ up to 72MHz, so let’s set the frequency to 72Mz. Now, we can choose a value for the Prescaler then put in the desired TOUT<\/sub> and solve for the auto-reload register’s value.<\/p>\n\n\n\n

    In LAB7, we’ll set our desired output time interval to be 100ms. We’ll toggle the LED once each 100ms and we’d like to set up the timer interrupt to give us this time interval. So, from the above equation, we can set the FCLK<\/sub> to be 72MHz. And let the Prescaler be 999<\/strong>. Now, the only unknown is the auto-reload (ARR) value. By solving for it, we’ll get 7199<\/strong>.<\/p>\n\n\n

    \n
    \"\"<\/figure>\n<\/div>\n\n\n

    <\/p>\n\n\n\n

    \n\n\n

    STM32 Timer Interrupt Example (LAB)<\/strong><\/h2>\n\n\n
    LAB Number<\/strong><\/span><\/td>7<\/span><\/td><\/tr>
    LAB Title<\/strong><\/span><\/td>Timer Mode Periodic Event<\/span><\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
      \n
    • Configure the general-purpose timer (TIM2) to operate in timer mode<\/span><\/li>\n\n\n\n
    • Set The Prescaler, and the Preload value so that the output Time interval is 100ms<\/span><\/li>\n\n\n\n
    • Toggle an output pin (LED) each 100ms in the timer overflow ISR<\/span><\/li>\n\n\n\n
    • Measure and verify the output signal’s timing<\/span><\/li>\n<\/ul>\n\n\n\n
      \n\n\n

      STM32 Timer Interrupt Example Project (Steps)<\/strong><\/h2>\n\n\n

      Step1<\/span>: Open CubeMX & Create New Project<\/strong><\/p>\n\n\n

      \n
      \"STM32<\/figure>\n<\/div>\n\n\n

      <\/p>\n\n\n\n

      Step2<\/span>: Choose The Target MCU & Double-Click Its Name<\/strong><\/p>\n\n\n

      \n
      \"STM32<\/figure>\n<\/div>\n\n\n

      <\/p>\n\n\n\n

      Step3<\/span>: Click On The Pin You Want To Configure As An Output & Select Output Option<\/strong><\/p>\n\n\n\n

      Let it be B13<\/strong><\/span> pin for example! (The onBoard LED Pin<\/strong><\/span>)<\/p>\n\n\n\n

      Step4<\/span>: Configure Timer2 Peripheral<\/strong><\/p>\n\n\n\n

      As we’ve calculated earlier, the Prescaler will be 999, and the Preload value will be 7199. And the timer module will be clocked at the internal clock frequency.<\/p>\n\n\n

      \n
      \"\"<\/figure>\n<\/div>\n\n\n

      <\/p>\n\n\n\n

      Step5<\/span>: Enable The Timer Interrupt Signal In NVIC Tab<\/strong><\/p>\n\n\n

      \n
      \"STM32<\/figure>\n<\/div>\n\n\n

      <\/p>\n\n\n\n

      Step6<\/span>: Set The RCC External Clock Source<\/strong><\/p>\n\n\n

      \n
      \"STM32<\/figure>\n<\/div>\n\n\n

      <\/p>\n\n\n\n

      Step7<\/span>: Go To The Clock Configuration<\/strong><\/p>\n\n\n\n

      Step8<\/span>: Set The System Clock To Be 72MHz Or Whatever You Want<\/strong><\/p>\n\n\n

      \n
      \"STM32<\/figure>\n<\/div>\n\n\n

      <\/p>\n\n\n\n

      Step9<\/span>: Name & Generate The Project Initialization Code For CubeIDE or The IDE You’re Using<\/strong><\/p>\n\n\n\n

      Then, open the project in the IDE you’re using. And head over to the main.c file. So we can start writing the application code and have a look at the initialization code generated by the STM32 CubeMX tool.<\/span><\/p>\n\n\n\n

      \n\n\n

      STM32 Timer Interrupt Example Code in CubeMX IDE<\/strong><\/h2>\n\n\n

      Here is the generated initialization code in the main.c file<\/p>\n\n\n\n

      #include \"main.h\"\n\nTIM_HandleTypeDef htim2;\n\nvoid SystemClock_Config(void);\nstatic void MX_GPIO_Init(void);\nstatic void MX_TIM2_Init(void);\n\nint main(void)\n{\n\n  HAL_Init();\n  SystemClock_Config();\n  MX_GPIO_Init();\n  MX_TIM2_Init();\n\n  while (1)\n  {\n\n  }\n\n}<\/pre>\n\n\n\n
      <\/p>\n\n\n\n
      Now, the application we’re currently developing is an LED toggle in the ISR for the timer module. So, open the stm32f1xx_it.c<\/code> file to find the timer interrupt handler, which is this function TIM2_IRQHandler()<\/code>. Hover over the HAL_TIM_IRQHandler()<\/code> function and right-click to navigate to its implementation.<\/p>\n\n\n\n
      void TIM2_IRQHandler(void)\n{\n\n  HAL_TIM_IRQHandler(&htim2);\n\n}<\/pre>\n\n\n\n
      <\/p>\n\n\n\n
      After navigating to the timer interrupt handler routine, you’ll find the following implementation. In this code, we’re searching for the callback function’s name that gets called when an overflow interrupt occurs. You can notice that all sources share the same interrupt signal output compare match, overflow, input capture, etc.<\/p>\n\n\n\n
      void HAL_TIM_IRQHandler(TIM_HandleTypeDef *htim)\n{\n  \/\/ Other timer interrupts events..\n  \/\/..\n  \/\/..\n  \/\/..\n  \/* TIM Update event *\/\n  if (__HAL_TIM_GET_FLAG(htim, TIM_FLAG_UPDATE) != RESET)\n  {\n    if (__HAL_TIM_GET_IT_SOURCE(htim, TIM_IT_UPDATE) != RESET)\n    {\n      __HAL_TIM_CLEAR_IT(htim, TIM_IT_UPDATE);\n      #if (USE_HAL_TIM_REGISTER_CALLBACKS == 1)\n        htim->PeriodElapsedCallback(htim);\n      #else\n        HAL_TIM_PeriodElapsedCallback(htim);\n      #endif \/* USE_HAL_TIM_REGISTER_CALLBACKS *\/\n    }\n  }\n  \/\/..\n  \/\/..\n  \/\/ Other timer interrupts events..\n}<\/pre>\n\n\n\n
      <\/p>\n\n\n\n
      Now, we’ve got the callback function’s name that gets called whenever timer overflow occurs. It’s HAL_TIM_PeriodElapsedCallback()<\/code>. So, we’ll write our own implementation for it in the application file (main.c<\/code>). And a mention-worthy point is that you also have to enable (start) the timer so it gets clocked and starts counting, otherwise, it’ll remain IDLE.<\/p>\n\n\n\n
      Full LAB Code (main.c)<\/strong><\/p>\n\n\n\n
      #include \"main.h\"\n\nTIM_HandleTypeDef htim2;\n\nvoid SystemClock_Config(void);\nstatic void MX_GPIO_Init(void);\nstatic void MX_TIM2_Init(void);\n\nint main(void)\n{\n\n  HAL_Init();\n  SystemClock_Config();\n  MX_GPIO_Init();\n  MX_TIM2_Init();\n  HAL_TIM_Base_Start_IT(&htim2);\n\n  while (1)\n  {\n\n  }\n\n}\n\nvoid HAL_TIM_PeriodElapsedCallback(TIM_HandleTypeDef* htim)\n{\n    HAL_GPIO_TogglePin(GPIOB, GPIO_PIN_13);\n}<\/pre>\n\n\n\n
      <\/p>\n\n\n\n
      Build & Flash The Code And Let’s Test The Results!<\/span><\/p>\n\n\n\n
      \n\n\n
      Testing The STM32 Timer Example Project<\/strong><\/h2>\n\n\n
      Step0<\/span>: Refer To The Blue Pill Board Schematic & Pinout<\/strong><\/p>\n\n\n\n
      Step1<\/span>: Connect The ST-Link To The USB Port & SWD Pins On Board<\/strong><\/p>\n\n\n
      \n
      \"STM32<\/figure>\n<\/div>\n\n\n
      Step2<\/span>: Click The Debug Button To Compile The Code & Flash It To The Board & Start A Debugging Session<\/strong><\/p>\n\n\n\n
      Step3<\/span>: You Can Stop The Debugging Session Or Keep It Going. But You Need To Restart The MCU Once To Run The New Application At The Booting Process.<\/strong><\/p>\n\n\n
      The Results of This LAB<\/span><\/strong><\/span><\/h3>\n\n\n
      Test Video<\/strong><\/p>\n\n\n\n
      \n