Enable RTC for all platforms and add cli date command (#252)

* F2: enable RTC. Cli: add date command.

firmware/targets/f2/Src/main.c

@@ -22,6 +22,7 @@
 #include "cmsis_os.h"
 #include "adc.h"
 #include "comp.h"
+#include "rtc.h"
 #include "spi.h"
 #include "tim.h"
 #include "usart.h"
@@ -101,6 +102,7 @@ int main(void)
   MX_USART1_UART_Init();
   MX_TIM8_Init();
   MX_TIM2_Init();
+  MX_RTC_Init();
   /* USER CODE BEGIN 2 */
   MX_FATFS_Init();
   delay_us_init_DWT();
@@ -135,11 +137,16 @@ void SystemClock_Config(void)
   RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};
   RCC_PeriphCLKInitTypeDef PeriphClkInit = {0};
 
+  /** Configure LSE Drive Capability
+  */
+  HAL_PWR_EnableBkUpAccess();
+  __HAL_RCC_LSEDRIVE_CONFIG(RCC_LSEDRIVE_LOW);
   /** Initializes the RCC Oscillators according to the specified parameters
   * in the RCC_OscInitTypeDef structure.
   */
-  RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSE;
+  RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSE|RCC_OSCILLATORTYPE_LSE;
   RCC_OscInitStruct.HSEState = RCC_HSE_ON;
+  RCC_OscInitStruct.LSEState = RCC_LSE_ON;
   RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
   RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSE;
   RCC_OscInitStruct.PLL.PLLM = 2;
@@ -164,10 +171,11 @@ void SystemClock_Config(void)
   {
     Error_Handler();
   }
-  PeriphClkInit.PeriphClockSelection = RCC_PERIPHCLK_USART1|RCC_PERIPHCLK_USB
-                              |RCC_PERIPHCLK_ADC;
+  PeriphClkInit.PeriphClockSelection = RCC_PERIPHCLK_RTC|RCC_PERIPHCLK_USART1
+                              |RCC_PERIPHCLK_USB|RCC_PERIPHCLK_ADC;
   PeriphClkInit.Usart1ClockSelection = RCC_USART1CLKSOURCE_PCLK2;
   PeriphClkInit.AdcClockSelection = RCC_ADCCLKSOURCE_SYSCLK;
+  PeriphClkInit.RTCClockSelection = RCC_RTCCLKSOURCE_LSE;
   PeriphClkInit.UsbClockSelection = RCC_USBCLKSOURCE_PLLSAI1;
   PeriphClkInit.PLLSAI1.PLLSAI1Source = RCC_PLLSOURCE_HSE;
   PeriphClkInit.PLLSAI1.PLLSAI1M = 2;