1 files changed, 22 insertions, 13 deletions

diff --git a/nuttx/configs/README.txt b/nuttx/configs/README.txt
index 46b41d1ab..3ed5d2563 100644
--- a/nuttx/configs/README.txt
+++ b/nuttx/configs/README.txt
@@ -609,20 +609,29 @@ defconfig -- This is a configuration file similar to the Linux
 
 	RTC
 
-		CONFIG_RTC - Enables general support for a hardware RTC. Specific
+		CONFIG_RTC - Enables general support for a hardware RTC.  Specific
 		  architectures may require other specific settings.
-		CONFIG_RTC_HIRES - The typical RTC keeps time to resolution of 1
-		  second, usually supporting a 32-bit time_t value.  In this case,
-		  the RTC is used to "seed" the normal NuttX timer and the
-		  NuttX timer provides for higher resoution time. If CONFIG_RTC_HIRES
-		  is enabled in the NuttX configuration, then the RTC provides higher
-		  resolution time and completely replaces the system timer for purpose of
-		  date and time.
-		  CONFIG_RTC_FREQUENCY - If CONFIG_RTC_HIRES is defined, then the
-		  frequency of the high resolution RTC must be provided.  If CONFIG_RTC_HIRES
-		  is not defined, CONFIG_RTC_FREQUENCY is assumed to be one.
-		CONFIG_RTC_ALARM - Enable if the RTC hardware supports setting of an alarm. 
-		  A callback function will be executed when the alarm goes off
+		CONFIG_RTC_DATETIME - There are two general types of RTC:  (1) A simple
+		  battery backed counter that keeps the time when power is down, and (2)
+		   A full date / time RTC the provides the date and time information, often
+		  in BCD format.  If CONFIG_RTC_DATETIME is selected, it specifies this
+		  second kind of RTC. In this case, the RTC is used to "seed" the normal
+		  NuttX timer and the NuttX system timer provides for higher resoution
+		  time.
+		CONFIG_RTC_HIRES - If CONFIG_RTC_DATETIME not selected, then the simple,
+		  battery backed counter is used.  There are two different implementations
+		  of such simple counters based on the time resolution of the counter:
+		  The typical RTC keeps time to resolution of 1 second, usually
+		  supporting a 32-bit time_t value.  In this case, the RTC is used to
+		  "seed" the normal NuttX timer and the NuttX timer provides for higher
+		  resoution time. If CONFIG_RTC_HIRES is enabled in the NuttX configuration,
+		  then the RTC provides higher resolution time and completely replaces the
+		  system timer for purpose of date and time.
+		CONFIG_RTC_FREQUENCY - If CONFIG_RTC_HIRES is defined, then the frequency
+		  of the high resolution RTC must be provided.  If CONFIG_RTC_HIRES is
+		  not defined, CONFIG_RTC_FREQUENCY is assumed to be one.
+		CONFIG_RTC_ALARM - Enable if the RTC hardware supports setting of an
+		  alarm.  A callback function will be executed when the alarm goes off
 
 	SPI driver