HAL_UART_RegisterCallback(&huart3, HAL_UART_TX_COMPLETE_CB_ID, User_UartCompleteCallback) This should be done after the MX peripheral initialization, please rely on the USER CODE comment label as a reference. In the main function, we need to associate the callback with the interrupt source by using the Register callback function. Void User_TIMPeriodElapsedCallback(TIM_HandleTypeDef *htim) Void User_UartCompleteCallback(UART_HandleTypeDef *huart) You can select any name you want, just make sure to follow the function’s arguments and return method as mentioned before. The periodElapsed variable is used to control the application flow based on timer interruptions.Īdd the function’s prototypes for each custom callback (one for the UART and another for the timer). The message array stores the message that is sent through the UART. Going back to the main.c file, define the following variables: /* USER CODE BEGIN PV */ Now, that all the preparations for using the Register callback feature are ready, let us dive into an example using that. Source: Author’s screenshot.įigure 10 – TIM Callback structure. See the examples below:įigure 9 – UART Callback structure. You can find the correct structure in the p_CallbackTypeDef (like pUART_CallbackTypeDef). Just make sure that your function respects the same structure as the HAL excepts. Source: Author’s screenshot.įinally, the last parameter is a pointer to your custom CallBack function. Source: Author’s screenshot.įigure 8 – List of TIM CallBack IDs. See figures 7 and 8.įigure 7 – List of UART CallBack IDs. A list of these IDs can be found in the respective peripheral HAL driver headers. The second parameter is a CallBack ID, which points to which the interrupt source calls the given CallBack. The first one is a pointer to the peripheral handler, &huart3 and &htim2 for the UART3 and TIM2 respectively. Note that we have some parameters to fill. To apply it for the UART and TIM, the following functions should be called: HAL_StatusTypeDef HAL_UART_RegisterCallback(UART_HandleTypeDef *huart, HAL_UART_CallbackIDTypeDef CallbackID, pUART_CallbackTypeDef pCallback)Īlso: HAL_StatusTypeDef HAL_TIM_RegisterCallback(TIM_HandleTypeDef *htim, HAL_TIM_CallbackIDTypeDef CallbackID, pTIM_CallbackTypeDef pCallback) In the main.c file, we should register the callback functions for the peripherals we want. Now, that all the settings are done, the code can be generated by clicking on the respective button or just pressing the shortcut alt + k. For that, the UART and TIM register callbacks should be enabled under project manager -> advanced settings as shown in figure 6.įigure 6 – Enabling the Register CallBack for UART and TIM. The last step, before the code generation, is to enable the register callback. In this tab, the HCLK frequency needs to be changed to 250 MHz (this frequency matches the TIM2 settings for the 1 second time base).įigure 5 – Clock configuration settings. The next changes are made at the clock configuration tab. NVIC: Enable both USART3’s and TIM2’s ISRs.įigure 4 – MCU Project Settings.PA5 as GPIO Output with USER_LED label.In this project, the following settings are applied: So, grab your coffee, settle into your chair, and let us start coding!įigure 2 – Connection between MCU’s USART3 and ST-LINK's VCOM PortĬreate a project for the STM32H503RB using the STM32CubeIDE. By the end of this article, you should have the necessary knowledge to do your own Register callback implementations in any kind of application. Two callbacks are registered: one for the UART_Tx and the other one for the timer overflow, also known as period elapsed interrupt. Furthermore, we use the TIM2 and the board’s user LED (figure 3). In this demonstration, we use the STLINK VCOM Port connected to the MCU's USART3 (figure 2). This means you can use a custom function as the callback for any desired peripheral interrupt source in your project. The Register callback feature allows you to register a custom callback for interruptions from a specific peripheral.
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