stm32H7 RTC HAL

### STM32H7 RTC HAL Library Usage For the STM32H7 microcontroller series, configuring and using the Real-Time Clock (RTC) module with the Hardware Abstraction Layer (HAL) library involves several key steps to ensure proper initialization and operation of this peripheral. To manually add the RTC functionality without utilizing STM32CubeMX: - Copy `rtc.c` and `rtc.h` files generated by a method such as STM32CubeMX into your project. - Enable the macro definition `HAL_RTC_MODULE_ENABLED` within `stm32h7xx_hal_conf.h`. - Adjust configurations according to specific requirements of the current engineering environment[^1]. Regarding Systick functionalities which are initialized after calling `HAL_Init()`, these include but not limited to incrementing ticks, getting tick count or priority level, setting/getting tick frequency, delaying execution based on millisecond counts, suspending/resuming ticking behavior. However, direct correlation between SysTick operations and RTC is minimal unless specifically programmed otherwise[^2]. When dealing specifically with UART communication alongside RTC setup, an example function demonstrates how characters can be transmitted over USART2 interface through HAL functions like so: ```c int fputc(int ch, FILE *f) { HAL_UART_Transmit(&huart2, (uint8_t*)&ch, 1, 0xFFFF); return ch; } ``` This snippet shows integration points where serial communications might interact indirectly when debugging or logging from within applications that utilize both peripherals simultaneously[^3]. In terms of enabling external low-speed clock sources necessary for accurate timekeeping provided by RTC hardware, along with other settings related to calendar features and interrupt handling mechanisms, one should also consider initializing parameters either via graphical tools offered by development environments or directly coding them at startup sequences before entering main application logic loops[^4]: ```c // Example configuration excerpt RCC_OscInitTypeDef RCC_OscInitStruct = {0}; RCC_PeriphCLKInitTypeDef PeriphClkInitStruct = {0}; /* Initializes the CPU, AHB and APB busses clocks */ RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_LSI | RCC_OSCILLATORTYPE_HSE; ... PeriphClkInitStruct.PeriphClockSelection = RCC_PERIPHCLK_RTC; PeriphClkInitStruct.RTCClockSelection = RCC_RTCCLKSOURCE_LSI; if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK || \ HAL_RCCEx_PeriphCLKConfig(&PeriphClkInitStruct) != HAL_OK){ Error_Handler(); } __HAL_RCC_RTC_ENABLE(); // Initialize RTC structure here... HAL_RTC_Init(&hrtc); // Optionally set initial date/time values if needed ```