diff --git a/ChangeLog b/ChangeLog
index a3547a2ac3d..e9174fb5303 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1725,3 +1725,7 @@
 
 6.3 2011-xx-xx Gregory Nutt <spudmonkey@racsa.co.cr>
 
+	* Remove clock_getutc().  It is replaces with clock_gettime(CLOCK_ACTIVETIME).
+	  Add other RTC related changes provided by Uros Platise.
+
+
diff --git a/Documentation/NuttxPortingGuide.html b/Documentation/NuttxPortingGuide.html
index 4f9b0694f8a..c7a56927fbe 100644
--- a/Documentation/NuttxPortingGuide.html
+++ b/Documentation/NuttxPortingGuide.html
@@ -91,7 +91,8 @@
       <a href="#updisableirq">4.1.16 <code>up_disable_irq()</code></a><br>
       <a href="#upenableirq">4.1.17 <code>up_enable_irq()</code></a><br>
       <a href="#upprioritizeirq">4.1.18 <code>up_prioritize_irq()</code></a></br>
-      <a href="#upputc">4.1.19 <code>up_putc()</code></a>
+      <a href="#upputc">4.1.19 <code>up_putc()</code></a></br>
+      <a href="#systemtime">4.1.20 System Time and Clock</a>
     </ul>
     <a href="#exports">4.2 APIs Exported by NuttX to Architecture-Specific Logic</a>
     <ul>
@@ -1642,6 +1643,90 @@ The system can be re-made subsequently by just typing <code>make</code>.
   Output one character on the console
 </p>
 
+<h3><a name="systemtime">4.1.20 System Time and Clock</a></h3>
+
+<h4>4.1.20.1 UTC Time Representation</h4>
+<p>
+  To enable UTC time representation use option:
+</p>
+<ul><pre>
+CONFIG_SYSTEM_UTC=y
+</pre></ul>
+<p>
+  which adds the following variables:
+</p>
+<ul>
+  <li><code>g_system_utc</code> (seconds, 4 bytes)</li>
+  <li><code>g_tickcount</code> (timer ticks, 1-2 bytes typically)</li>
+</ul>
+<p>
+  and replaces:
+</p>
+<ul>
+  <li><code>g_system_timer</code>(4 bytes)</li>
+  <li><code>g_basetime</code>(8 bytes)</li>
+  <li><code>g_tickbias</code>(4 bytes)</li>
+</ul>
+<p>
+  Otherwise internal time is computed from 32-bit running tick timer
+  <code>g_systemtimer</code> the start date <code>g_basetime</code> and time offset the <code>g_tickbias</code>.
+</p>
+
+<h4>4.1.20.2 Hardware</h4>
+<p>
+  To enable hardware module use option:
+<p>
+<ul><pre>
+CONFIG_RTC=y
+</pre></ul>
+<p>
+  which requires the following three base functions to read time:
+</p>
+<ul>
+  <li><code>up_rtcinitialize()</code></li>
+  <li><code>up_rtc_gettime()</code>. UTC time in seconds.</li>
+  <li><code>up_rtc_getclock()</code>. Replacement for <code>g_system_tick</code></li>
+</ul>
+<p>
+  This module depends on <code>CONFIG_SYSTEM_UTC=y</code>.
+</p>
+
+<h4>4.1.20.3 System Tick and Time</h4>
+<p>
+  The system tick is represented by, when <code>CONFIG_SYSTEM_UTC=n</code>:
+</p>
+<ul>
+  <li><code>g_system_timer</code></li>
+</ul>
+<p>
+  or, when <code>CONFIG_SYSTEM_UTC=y</code>
+</p>
+<ul>
+  <li><code>g_tickcount</code></li>
+  <li><code>g_system_utc</code></li>
+</ul>
+<p>
+  Running at rate of system base timer, used for time-slicing, and so forth.
+</p>
+<p>
+  If hardware RTC is present (<code>CONFIG_RTC</code>) and enabled, then after successful
+  initiliazation variables are overriden by calls to <code>up_rtc_getclock()</code> which is
+  running continously even in power-down modes.
+</p>
+<p>
+  In the case of <code>CONFIG_RTC</code> is set the <code>g_tickcount</code> and <code>g_system_utc</code> keep
+  counting at rate of a system timer, which however, is disabled in power-down
+  mode. By comparing this time and RTC (actual time) one may determine the
+  actual system active time. To retrieve that variable use:
+</p>
+<ul><pre>
+  <li><code>clock_gettime(CLOCK_ACTIVETIME, tp)</code>
+</pre></ul>
+<p>
+  If the <code>CLOCK_ACTIVETIME</code> time is never set it will serve as power-up time
+  minus all deep sleeps.
+</p>
+
 <h2><a name="exports">4.2 APIs Exported by NuttX to Architecture-Specific Logic</a></h2>
 <p>
   These are standard interfaces that are exported by the OS
diff --git a/configs/vsn/src/sif.c b/configs/vsn/src/sif.c
index 2d5351e87b1..4be21444438 100644
--- a/configs/vsn/src/sif.c
+++ b/configs/vsn/src/sif.c
@@ -508,8 +508,9 @@ int sif_main(int argc, char *argv[])
             return 0;
         }
         else if (!strcmp(argv[1], "time") && argc == 3) {
-            int val = atoi(argv[2]);
-            up_rtc_settime(val);
+            struct timespec t_set;
+            t_set.tv_sec = atoi(argv[2]);
+            clock_settime(CLOCK_REALTIME, &t_set);
         }
         else if (!strcmp(argv[1], "i2c") && argc == 3) {
             int val = atoi(argv[2]);
@@ -551,7 +552,13 @@ int sif_main(int argc, char *argv[])
     }
 
     fprintf(stderr, "%s:\tinit\n\tgpio\tA B\n\tpwr\tval\n", argv[0]);
-    fprintf(stderr, "time = %d / %d, time = %d\n", 
-        up_rtc_gettime(), up_rtc_getclock(), time(NULL) );
+    
+    struct timespec t_active;
+    clock_gettime(CLOCK_ACTIVETIME, &t_active);
+    
+    fprintf(stderr, "rtc time = %u / %u, active = %u / %u, time / systick = %u / %u\n", 
+        up_rtc_gettime(), up_rtc_getclock(),
+        t_active.tv_sec, t_active.tv_nsec,
+        time(NULL), clock_systimer() );
     return -1;
 }
diff --git a/include/nuttx/clock.h b/include/nuttx/clock.h
index cde1dd2dbbb..71f0c7e8a08 100644
--- a/include/nuttx/clock.h
+++ b/include/nuttx/clock.h
@@ -128,15 +128,18 @@
 #if __HAVE_KERNEL_GLOBALS
 extern volatile uint32_t g_system_timer;
 extern volatile uint32_t g_system_utc;
-#endif
 
-#if !defined(CONFIG_RTC) && __HAVE_KERNEL_GLOBALS
+#if TICK_PER_SEC > 32767
+extern volatile uint32_t g_tickcount;
+#elif TICK_PER_SEC > 255
+extern volatile uint16_t g_tickcount;
+#else
+extern volatile uint8_t  g_tickcount;
+#endif
+#endif /* __HAVE_KERNEL_GLOBALS */
+
+#if !defined(CONFIG_SYSTEM_UTC) && __HAVE_KERNEL_GLOBALS
 #define clock_systimer() g_system_timer
-
-#if defined(CONFIG_SYSTEM_UTC)
-#define clock_getutc()   g_system_utc
-#endif
-
 #endif
 
 /****************************************************************************
@@ -173,27 +176,6 @@ extern "C" {
 EXTERN uint32_t clock_systimer(void);
 #endif
 
-/****************************************************************************
- * Function:  clock_getutc
- *
- * Description:
- *   Return the current value of the system timer counter, which is only
- *   enabled when system is in active mode.
- *
- * Parameters:
- *   None
- *
- * Return Value:
- *   The current value of the system time counter
- *
- * Assumptions:
- *
- ****************************************************************************/
-
-#if defined(CONFIG_SYSTEM_UTC) && !__HAVE_KERNEL_GLOBALS
-EXTERN time_t clock_getutc(void);
-#endif
-
 #undef EXTERN
 #ifdef __cplusplus
 }
diff --git a/include/time.h b/include/time.h
index fab20e020bd..c52e74bf2d3 100644
--- a/include/time.h
+++ b/include/time.h
@@ -60,28 +60,37 @@
  */
 
 #ifdef CONFIG_MSEC_PER_TICK
-# define CLK_TCK        (1000/CONFIG_MSEC_PER_TICK)
-# define CLOCKS_PER_SEC (1000/CONFIG_MSEC_PER_TICK)
+# define CLK_TCK           (1000/CONFIG_MSEC_PER_TICK)
+# define CLOCKS_PER_SEC    (1000/CONFIG_MSEC_PER_TICK)
 #else
-# define CLK_TCK        (100)
-# define CLOCKS_PER_SEC (100)
+# define CLK_TCK           (100)
+# define CLOCKS_PER_SEC    (100)
 #endif
 
 /* This is the only clock_id supported by the "Clock and Timer
  * Functions."
  */
 
-#define CLOCK_REALTIME 0
+#define CLOCK_REALTIME     0
+
+/* Non-standard. Returns active UTC time, which is disabled during
+ * power down modes. Unit is 1 second.
+ */
+
+#ifdef CONFIG_RTC
+#  define CLOCK_ACTIVETIME 1
+#endif
+
 #define CLOCK_ABSTIME
 
 /* This is a flag that may be passed to the timer_settime() function */
 
-#define TIMER_ABSTIME 1
+#define TIMER_ABSTIME      1
 
 /* Local time is the same as gmtime in this implementation */
 
-#define localtime(c)     gmtime(c)
-#define localtime_r(c,r) gmtime_r(c,r)
+#define localtime(c)       gmtime(c)
+#define localtime_r(c,r)   gmtime_r(c,r)
 
 /********************************************************************************
  * Global Type Declarations
diff --git a/sched/Makefile b/sched/Makefile
index 2ad17f8260c..859bd57b4cb 100644
--- a/sched/Makefile
+++ b/sched/Makefile
@@ -80,10 +80,6 @@ CLOCK_SRCS	= clock_initialize.c clock_settime.c clock_gettime.c clock_getres.c \
 		  clock_time2ticks.c clock_abstime2ticks.c clock_ticks2time.c \
 		  clock_gettimeofday.c clock_systimer.c
 
-ifeq ($(CONFIG_SYSTEM_UTC),y)
-CLOCK_SRCS	+= clock_getutc.c
-endif
-
 SIGNAL_SRCS	= sig_initialize.c \
 		  sig_action.c sig_procmask.c sig_pending.c sig_suspend.c \
 		  sig_kill.c sig_queue.c sig_waitinfo.c sig_timedwait.c \
diff --git a/sched/clock_gettime.c b/sched/clock_gettime.c
index f3ffe2a6c01..59e5b604c31 100644
--- a/sched/clock_gettime.c
+++ b/sched/clock_gettime.c
@@ -38,6 +38,7 @@
  ************************************************************************/
 
 #include <nuttx/config.h>
+#include <nuttx/rtc.h>
 
 #include <stdint.h>
 #include <time.h>
@@ -95,17 +96,13 @@ int clock_gettime(clockid_t clock_id, struct timespec *tp)
 
   sdbg("clock_id=%d\n", clock_id);
 
-  /* Only CLOCK_REALTIME is supported */
+  /* CLOCK_REALTIME - POSIX demands this to be present. This is the wall
+   * time clock.
+   */
 
-  if (clock_id != CLOCK_REALTIME)
-    {
-      sdbg("Returning ERROR\n");
-
-      *get_errno_ptr() = EINVAL;
-      ret = ERROR;
-    }
-  else
+  if (clock_id == CLOCK_REALTIME && tp)
     {
+#ifndef CONFIG_SYSTEM_UTC
       /* Get the elapsed time since power up (in milliseconds) biased
        * as appropriate.
        */
@@ -142,10 +139,46 @@ int clock_gettime(clockid_t clock_id, struct timespec *tp)
 
       tp->tv_sec  = (time_t)secs;
       tp->tv_nsec = (long)nsecs;
+      
+#else   /* if CONFIG_SYSTEM_UTC=y */
+
+#ifdef CONFIG_RTC
+      if (g_rtc_enabled)
+        {
+          tp->tv_sec  = up_rtc_gettime();
+          tp->tv_nsec = (up_rtc_getclock() & (RTC_CLOCKS_PER_SEC-1) ) * (1000000000/TICK_PER_SEC);
+        }
+      else
+#endif
+        {
+          tp->tv_sec  = g_system_utc;
+          tp->tv_nsec = g_tickcount * (1000000000/TICK_PER_SEC);
+        }
+#endif
 
       sdbg("Returning tp=(%d,%d)\n",
            (int)tp->tv_sec, (int)tp->tv_nsec);
     }
 
+ /* CLOCK_ACTIVETIME is non-standard. Returns active UTC time, which is
+  * disabled during power down modes. Unit is 1 second.
+  */
+
+#ifdef CONFIG_RTC
+  else if (clock_id == CLOCK_ACTIVETIME && g_rtc_enabled && tp)
+    {
+      tp->tv_sec  = g_system_utc;
+      tp->tv_nsec = g_tickcount * (1000000000/TICK_PER_SEC);
+    }
+#endif
+
+  else
+    {
+      sdbg("Returning ERROR\n");
+
+      errno = EINVAL;
+      ret = ERROR;
+    }
+
   return ret;
 }
diff --git a/sched/clock_getutc.c b/sched/clock_getutc.c
deleted file mode 100644
index 95c0970199e..00000000000
--- a/sched/clock_getutc.c
+++ /dev/null
@@ -1,92 +0,0 @@
-/****************************************************************************
- * sched/clock_getutc.c
- *
- *   Copyright (C) 2011 Gregory Nutt. All rights reserved.
- *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- *
- * 1. Redistributions of source code must retain the above copyright
- *    notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- *    notice, this list of conditions and the following disclaimer in
- *    the documentation and/or other materials provided with the
- *    distribution.
- * 3. Neither the name NuttX nor the names of its contributors may be
- *    used to endorse or promote products derived from this software
- *    without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
- * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
- * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
- * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
- * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
- * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
- * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
- * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
- * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
- * POSSIBILITY OF SUCH DAMAGE.
- *
- ****************************************************************************/
-
-/****************************************************************************
- * Included Files
- ****************************************************************************/
-
-#include <nuttx/config.h>
-
-#include <stdint.h>
-#include <nuttx/clock.h>
-#include <nuttx/time.h>
-#include <nuttx/rtc.h>
-
-#if !defined(CONFIG_DISABLE_CLOCK) && defined(CONFIG_SYSTEM_UTC) && !defined(clock_getutc)
-     
-/****************************************************************************
- * Pre-processor Definitions
- ****************************************************************************/
-
-/****************************************************************************
- * Private Data
- ****************************************************************************/
-
-/****************************************************************************
- * Public Functions
- ****************************************************************************/
-
-/****************************************************************************
- * Function:  clock_getutc
- *
- * Description:
- *   Return the current value of the system timer counter, which is only
- *   enabled when system is in active mode.
- *
- * Parameters:
- *   None
- *
- * Return Value:
- *   The current value of the system time counter
- *
- * Assumptions:
- *
- ****************************************************************************/
-
-time_t clock_getutc(void)
-{
-#ifdef CONFIG_RTC
-  if (g_rtc_enabled)
-    {
-      return up_rtc_gettime();
-	}
-  else
-#endif
-    {
-      return g_system_utc;
-	}
-}
-
-#endif /* CONFIG_DISABLE_CLOCK && CONFIG_SYSTEM_UTC */
diff --git a/sched/clock_initialize.c b/sched/clock_initialize.c
index 91220c19e72..8919b6005d5 100644
--- a/sched/clock_initialize.c
+++ b/sched/clock_initialize.c
@@ -60,9 +60,13 @@
 #define SEC_PER_HOUR ((time_t)60 * SEC_PER_MIN)
 #define SEC_PER_DAY  ((time_t)24 * SEC_PER_HOUR)
 
-/* Defined just so the UTC counter and system counter/timer look similar */
+/* Macro to increment the system timer -- or not */
 
-#define incr_systimer() g_system_timer++
+#ifndef CONFIG_SYSTEM_UTC
+#  define incr_systimer() g_system_timer++
+#else
+#  define incr_systimer()
+#endif
 
 /****************************************************************************
  * Private Type Declarations
@@ -80,14 +84,13 @@
  * Public Variables
  ****************************************************************************/
 
-volatile clock_t g_system_timer = 0;
-
 #if CONFIG_SYSTEM_UTC
 volatile time_t  g_system_utc   = 0;
-#endif
-
+#else
+volatile clock_t g_system_timer = 0;
 struct timespec  g_basetime     = {0,0};
 uint32_t         g_tickbias     = 0;
+#endif
 
 /**************************************************************************
  * Private Variables
@@ -99,11 +102,11 @@ uint32_t         g_tickbias     = 0;
 
 #if CONFIG_SYSTEM_UTC
 #if TICK_PER_SEC > 32767
-static uint32_t g_tickcount = 0;
+volatile uint32_t g_tickcount = 0;
 #elif TICK_PER_SEC > 255
-static uint16_t g_tickcount = 0;
+volatile uint16_t g_tickcount = 0;
 #else
-static uint8_t  g_tickcount = 0;
+volatile uint8_t  g_tickcount = 0;
 #endif
 #endif /* CONFIG_SYSTEM_UTC */
 
@@ -153,32 +156,39 @@ static inline void incr_utc(void)
 
 void clock_initialize(void)
 {
+#ifndef CONFIG_SYSTEM_UTC
   time_t jdn = 0;
+#endif
 
   /* Initialize the real time close (this should be un-nesssary except on a
    * restart).
    */
 
-  g_system_timer = 0;
 #ifdef CONFIG_SYSTEM_UTC
   g_system_utc   = 0;
+#else
+  g_system_timer = 0;
 #endif
 
-  /* Do we have hardware periodic timer support? */
+  /* Do we have hardware RTC support? */
 
 #ifdef CONFIG_RTC
+
+#ifndef CONFIG_SYSTEM_UTC
+#  error In order to support hardware RTC system must have set the CONFIG_SYSTEM_UTC=y
+#endif
+
   up_rtcinitialize();
+#endif
+
+#ifndef CONFIG_SYSTEM_UTC
 
   /* Get the EPOCH-relative julian date from the calendar year,
    * month, and date
    */
 
-  if (g_rtc_enabled==false)
-#endif
-    {
-      jdn = clock_calendar2utc(CONFIG_START_YEAR, CONFIG_START_MONTH,
-                               CONFIG_START_DAY);
-    }
+  jdn = clock_calendar2utc(CONFIG_START_YEAR, CONFIG_START_MONTH,
+                           CONFIG_START_DAY);
 
   /* Set the base time as seconds into this julian day. */
 
@@ -188,6 +198,7 @@ void clock_initialize(void)
   /* These is no time bias from this time. */
 
   g_tickbias = 0;
+#endif
 }
 
 /****************************************************************************
diff --git a/sched/clock_settime.c b/sched/clock_settime.c
index 2af27acf1c0..72fb8276e6e 100644
--- a/sched/clock_settime.c
+++ b/sched/clock_settime.c
@@ -38,6 +38,7 @@
  ************************************************************************/
 
 #include <nuttx/config.h>
+#include <nuttx/rtc.h>
 
 #include <time.h>
 #include <errno.h>
@@ -90,16 +91,13 @@ int clock_settime(clockid_t clock_id, const struct timespec *tp)
 
   sdbg("clock_id=%d\n", clock_id);
 
-  /* Only CLOCK_REALTIME is supported */
+  /* CLOCK_REALTIME - POSIX demands this to be present. This is the wall
+   * time clock.
+   */
 
-  if (clock_id != CLOCK_REALTIME || !tp) 
-    {
-      sdbg("Returning ERROR\n");
-      *get_errno_ptr() = EINVAL;
-      ret = ERROR;
-    }
-  else
+  if (clock_id == CLOCK_REALTIME && tp) 
     {
+#ifndef CONFIG_SYSTEM_UTC
       /* Save the new base time. */
 
       g_basetime.tv_sec  = tp->tv_sec;
@@ -110,11 +108,44 @@ int clock_settime(clockid_t clock_id, const struct timespec *tp)
        */
 
       g_tickbias = clock_systimer();
+      
+#else   /* if CONFIG_SYSTEM_UTC=y */
+
+      /* We ignore everything below one second in time configuration */
+
+#ifdef CONFIG_RTC
+      if (g_rtc_enabled)
+        {
+          up_rtc_settime( tp->tv_sec );
+        } 
+      else
+#endif
+       g_system_utc = tp->tv_sec;
+
+#endif
 
       sdbg("basetime=(%d,%d) tickbias=%d\n",
           (int)g_basetime.tv_sec, (int)g_basetime.tv_nsec,
           (int)g_tickbias);
-  }
+    }
+
+ /* CLOCK_ACTIVETIME is non-standard. Returns active UTC time, which is
+  * disabled during power down modes. Unit is 1 second.
+  */
+
+#ifdef CONFIG_RTC
+  else if (clock_id == CLOCK_ACTIVETIME && g_rtc_enabled && tp) 
+    {
+      g_system_utc = tp->tv_sec;
+    }
+#endif
+
+  else 
+    {
+      sdbg("Returning ERROR\n");
+      *get_errno_ptr() = EINVAL;
+      ret = ERROR;
+    }
 
   return ret;
 }
diff --git a/sched/clock_systimer.c b/sched/clock_systimer.c
index c4560a8a184..a1219a681a5 100644
--- a/sched/clock_systimer.c
+++ b/sched/clock_systimer.c
@@ -83,17 +83,21 @@ uint32_t clock_systimer(void)
 
   /* Check if the periodic timer is initialized
    *
-   * Note that the unit of the g_system_timer and and up_rtc_getclock() must
-   * be the same in order (must have same [unit]) to allow smooth transitions.
+   * Note that the unit of the g_system_timer and and up_rtc_getclock() do
+   * not have the same unit.
    */
 
   if (g_rtc_enabled)
     {
-//	  return up_rtc_getclock();
+	  return up_rtc_getclock();
 	}
 #endif
 
+#ifndef CONFIG_SYSTEM_UTC
   return g_system_timer;
+#else
+  return g_system_utc * TICK_PER_SEC + g_tickcount;
+#endif
 }
 
 #endif /* !clock_systtimer */