{"id":2827,"date":"2024-09-06T15:25:41","date_gmt":"2024-09-06T15:25:41","guid":{"rendered":"https:\/\/iotthinghub.com\/?p=2827"},"modified":"2024-09-06T16:10:01","modified_gmt":"2024-09-06T16:10:01","slug":"rtc-in-stm32","status":"publish","type":"post","link":"https:\/\/iotthinghub.com\/?p=2827","title":{"rendered":"RTC In STM32"},"content":{"rendered":"\n

In RTC section we interface an I2<\/sup>C IC DS1307. The STM32 has built in RTC. In STM32 the real-time clock (RTC) is an independent BCD timer\/counter. The RTC provides a time of-day clock\/calendar with programmable alarm interrupt. The RTC includes also a periodic programmable wakeup flag with interrupt capability. Two 32-bit registers contain the seconds, minutes, hours (12- or 24-hour format), day (day of week), date (day of month), month, and year, expressed in binary coded decimal format (BCD). The sub-seconds value is also available in binary format. Compensations for 28-, 29- (leap year), 30-, and 31-day months are performed automatically. Daylight saving time compensation can also be performed. Let\u2019s start with some settings \u2013<\/p>\n\n\n\n

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Here we use external crystal 32.768KHz as low speed clock. Change the calendar according to your current time zone. Some useful HAL library as follow-<\/p>\n\n\n

\nHAL_RTC_SetTime(RTC_HandleTypeDef *hrtc, RTC_TimeTypeDef *sTime, uint32_t Format)\nHAL_RTC_SetDate(RTC_HandleTypeDef *hrtc, RTC_DateTypeDef *sDate, uint32_t Format)\nHAL_RTC_GetTime(RTC_HandleTypeDef *hrtc, RTC_TimeTypeDef *sTime, uint32_t Format)\nHAL_RTC_GetDate(RTC_HandleTypeDef *hrtc, RTC_DateTypeDef *sDate, uint32_t Format)\n<\/pre><\/div>\n\n\n
Here the format is either<\/p>\n\n\n\n
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  • RTC_FORMAT_BIN:  Binary data format<\/li>\n\n\n\n
  • RTC_FORMAT_BCD:  BCD data format<\/li>\n<\/ul>\n\n\n\n
    First we have to declare the time & date then assign the value and get the value. To define time & date as follow-<\/p>\n\n\n
    \nRTC_TimeTypeDef sTime;\nRTC_DateTypeDef sDate;\n<\/pre><\/div>\n\n\n
    In STM32Cube we can directly assign the date & time, but is not good practice. Let\u2019s assign some value to RTC-<\/p>\n\n\n
    \nsTime.Hours = 0x10;\nsTime.Minutes = 0x0;\nsTime.Seconds = 0x0;\nsDate.WeekDay = RTC_WEEKDAY_SATURDAY;\nsDate.Month = RTC_MONTH_SEPTEMBER;\nsDate.Date = 0x1;\nsDate.Year = 0x24;\nHAL_RTC_SetTime(&hrtc,&sTime,RTC_FORMAT_BCD);\nHAL_RTC_SetDate(&hrtc,&sDate,RTC_FORMAT_BCD);\n<\/pre><\/div>\n\n\n
    Reading procedure is very simple. Just use 2 lines-<\/p>\n\n\n
    \nHAL_RTC_GetTime(&hrtc,&sTime,RTC_FORMAT_BCD);\nHAL_RTC_GetDate(&hrtc,&sDate,RTC_FORMAT_BCD);\n<\/pre><\/div>\n\n\n
    All parameter returns in BCD format, just use %X in C language. The day & time zone as follow-<\/p>\n\n\n\n
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    For example to display all date & time as follow-<\/p>\n\n\n
    \nchar display_time[16]="IoTThingHuB.com ";\nvolatile char *day_name[8]={"Mon", "Tue", "Wed", "Thu", "Fri", "Sat","Sun"};\nvolatile char *day_zone[2]={"AM", "PM"};\nsprintf(display_time," %02X:%02X:%02X %s",sTime.Hours,sTime.Minutes,sTime.Seconds,day_zone[sTime.TimeFormat]);\nsprintf(display_time," %02X\/%02X\/%02X %s",sDate.Date,sDate.Month,sDate.Year,day_name[sDate.WeekDay-1]);\n<\/pre><\/div>\n\n\n
    In our previous article we discuss abut OLED interfacing, we will show the clock in OLED. The main program as follow(only the add parameter)-<\/p>\n\n\n
    \n#include "ssd1306.h"\nRTC_TimeTypeDef sTime;\nRTC_DateTypeDef sDate;\nchar display_time[16]="IoTThingHuB.com ";\nvolatile char *day_name[8]={"Mon", "Tue", "Wed", "Thu", "Fri", "Sat","Sun"};\nvolatile char *day_zone[2]={"AM", "PM"};\ninit_OLED();\nclear_display();\nOLCD_write_string(0,0," Real Time Clock");\nWhile(1){\n\tHAL_RTC_GetTime(&hrtc,&sTime,RTC_FORMAT_BCD);\n    HAL_RTC_GetDate(&hrtc,&sDate,RTC_FORMAT_BCD);\n    sprintf(display_time," %02X:%02X:%02X %s",sTime.Hours,sTime.Minutes,sTime.Seconds,day_zone[sTime.TimeFormat]);\n\tOLCD_write_string(4,0,display_time);\n\tsprintf(display_time," %02X\/%02X\/%02X %s",sDate.Date,sDate.Month,sDate.Year,day_name[sDate.WeekDay-1]);\n\tOLCD_write_string(6,0,display_time);\n}\n<\/pre><\/div>\n\n\n
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