diff --git a/application.c b/application.c
index 567800e..16346eb 100644
--- a/application.c
+++ b/application.c
@@ -15,13 +15,15 @@
 /** STM32F1 application example
  *  @file application.c
  *  @author King Kévin <kingkevin@cuvoodoo.info>
- *  @date 2016-2018
+ *  @date 2016-2019
  */
 
 /* standard libraries */
 #include <stdint.h> // standard integer types
 #include <stdlib.h> // standard utilities
 #include <string.h> // string utilities
+#include <time.h> // date/time utilities
+#include <ctype.h> // utilities to check chars
 
 /* STM32 (including CM3) libraries */
 #include <libopencmsis/core_cm3.h> // Cortex M3 utilities
@@ -47,6 +49,13 @@
 #include "menu.h" // menu utilities
 
 #define WATCHDOG_PERIOD 10000 /**< watchdog period in ms */
+/** set to 0 if the RTC is reset when the board is powered on, only indicates the uptime
+ *  set to 1 if VBAT can keep the RTC running when the board is unpowered, indicating the date and time
+ */
+#define RTC_DATE_TIME 1
+
+/** RTC time when device is started */
+static time_t time_start = 0;
 
 /** @defgroup main_flags flag set in interrupts to be processed in main task
  *  @{
@@ -91,6 +100,13 @@ static void command_version(void* argument);
  */
 static void command_uptime(void* argument);
 
+#if RTC_DATE_TIME
+/** show date and time
+ *  @param[in] argument date and time to set
+ */
+static void command_datetime(void* argument);
+#endif
+
 /** reset board
  *  @param[in] argument no argument required
  */
@@ -127,6 +143,16 @@ static const struct menu_command_t menu_commands[] = {
 		.argument_description = NULL,
 		.command_handler = &command_uptime,
 	},
+#if RTC_DATE_TIME
+	{
+		.shortcut = 'd',
+		.name = "date",
+		.command_description = "show date and time",
+		.argument = MENU_ARGUMENT_STRING,
+		.argument_description = "[YYYY-MM-DD HH:MM:SS]",
+		.command_handler = &command_datetime,
+	},
+#endif
 	{
 		.shortcut = 'r',
 		.name = "reset",
@@ -200,10 +226,43 @@ static void command_version(void* argument)
 static void command_uptime(void* argument)
 {
 	(void)argument; // we won't use the argument
-	uint32_t uptime = rtc_get_counter_val(); // get time from internal RTC
-	printf("uptime: %u.%02u:%02u:%02u\n", uptime/(24*60*60), (uptime/(60*60))%24, (uptime/60)%60, uptime%60);
+	uint32_t uptime = rtc_get_counter_val() - time_start; // get time from internal RTC
+	printf("uptime: %u.%02u:%02u:%02u\n", uptime / (24 * 60 * 60), (uptime / (60 * 60)) % 24, (uptime / 60) % 60, uptime % 60);
 }
 
+#if RTC_DATE_TIME
+static void command_datetime(void* argument)
+{
+	char* datetime = (char*)argument; // argument is optional date time
+	if (NULL == argument) { // no date and time provided, just show the current day and time
+		time_t time_rtc = rtc_get_counter_val(); // get time from internal RTC
+		struct tm* time_tm = localtime(&time_rtc); // convert time
+		printf("date: %d-%02d-%02d %02d:%02d:%02d\n", 1900 + time_tm->tm_year, time_tm->tm_mon, time_tm->tm_mday, time_tm->tm_hour, time_tm->tm_min, time_tm->tm_sec);
+	} else { // date and time provided, set it
+		const char* malformed = "date and time malformed, expecting YYYY-MM-DD HH:MM:SS\n";
+		struct tm time_tm; // to store the parsed date time
+		if (strlen(datetime) != (4 + 1 + 2 + 1 + 2) + 1 + (2 + 1 + 2 + 1 + 2)) { // verify date/time is long enough
+			printf(malformed);
+			return;
+		}
+		if (!(isdigit((int8_t)datetime[0]) && isdigit((int8_t)datetime[1]) && isdigit((int8_t)datetime[2]) && isdigit((int8_t)datetime[3]) && '-' == datetime[4] && isdigit((int8_t)datetime[5]) && isdigit((int8_t)datetime[6]) && '-' == datetime[7] && isdigit((int8_t)datetime[8]) && isdigit((int8_t)datetime[9]) && ' ' == datetime[10] && isdigit((int8_t)datetime[11]) && isdigit((int8_t)datetime[12]) && ':' == datetime[13] && isdigit((int8_t)datetime[14]) && isdigit((int8_t)datetime[15]) && ':' == datetime[16] && isdigit((int8_t)datetime[17]) && isdigit((int8_t)datetime[18]))) { // verify format (good enough to not fail parsing)
+			printf(malformed);
+			return;
+		}
+		time_tm.tm_year = strtol(&datetime[0], NULL, 10) - 1900; // parse year
+		time_tm.tm_mon = strtol(&datetime[5], NULL, 10); // parse month
+		time_tm.tm_mday = strtol(&datetime[8], NULL, 10); // parse day
+		time_tm.tm_hour = strtol(&datetime[11], NULL, 10); // parse hour
+		time_tm.tm_min = strtol(&datetime[14], NULL, 10); // parse minutes
+		time_tm.tm_sec = strtol(&datetime[17], NULL, 10); // parse seconds
+		time_t time_rtc = mktime(&time_tm); // get back seconds
+		time_start = time_rtc + (rtc_get_counter_val() - time_start); // update uptime with current date
+		rtc_set_counter_val(time_rtc); // save date/time to internal RTC
+		printf("date and time saved: %d-%02d-%02d %02d:%02d:%02d\n", 1900 + time_tm.tm_year, time_tm.tm_mon, time_tm.tm_mday, time_tm.tm_hour, time_tm.tm_min, time_tm.tm_sec);
+	}
+}
+#endif
+
 static void command_reset(void* argument)
 {
 	(void)argument; // we won't use the argument
@@ -291,6 +350,7 @@ void main(void)
 #endif
 	rtc_interrupt_enable(RTC_SEC); // enable RTC interrupt on "seconds"
 	nvic_enable_irq(NVIC_RTC_IRQ); // allow the RTC to interrupt
+	time_start = rtc_get_counter_val(); // get start time from internal RTC
 	printf("OK\n");
 
 	// setup terminal