diff --git a/ChangeLog b/ChangeLog
index 2e1c0b83034..1aeb41e3f07 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -5879,4 +5879,7 @@
 	  (2013-10-24).
 	* configs/sama5d3x-ek/src/sam_adc.c:  Integrate support for the
 	  apps/examples/adc into the SAMA5D3x-EK configuration (2013-10-24).
+	* include/nuttx/fs/ioctl.h and arch/arm/src/sama5/sam_adc.c:  Add
+	  and ioctl command that can be used to trigger ADC/DAC conversion
+	  (2015-10-25).
 
diff --git a/TODO b/TODO
index 4736b88b3b4..c941308755e 100644
--- a/TODO
+++ b/TODO
@@ -18,7 +18,7 @@ nuttx/
  (16)  Network (net/, drivers/net)
   (4)  USB (drivers/usbdev, drivers/usbhost)
  (11)  Libraries (libc/, )
- (10)  File system/Generic drivers (fs/, drivers/)
+ (11)  File system/Generic drivers (fs/, drivers/)
   (5)  Graphics subystem (graphics/)
   (1)  Pascal add-on (pcode/)
   (1)  Documentation (Documentation/)
@@ -1163,6 +1163,21 @@ o File system / Generic drivers (fs/, drivers/)
   Priority:    Low.  Nothing is broken.  This is an enhancement that would
                improve the OS design and possible reduce some FLASH usage
 
+  Title:       UNIFIED DESCRIPTOR REPRESENTATION
+  Descripton:  There are two separate ranges of descriptors for file and
+               socket descriptors: if a descriptor is in one range then it is
+               recognized as a file descriptor; if it is in another range
+               then it is recognized as a socket descriptor.  These separate
+               descriptor ranges can cause problems, for example, they makes
+               dup'ing descriptors with dup2() problematic.  The two groups
+               of descriptors are really indices into two separate tables:
+               On an array of file structures and the other an array of
+               socket structures.  There really should be one array that
+               is a union of file and socket descriptors.  Then socket and
+               file decriptors could lie in the same range.
+  Status:      Open
+  Priority:    Low
+
 o Graphics subystem (graphics/)
   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
diff --git a/arch/arm/src/sama5/sam_adc.c b/arch/arm/src/sama5/sam_adc.c
index cd7ca45fecc..5af5f0d4e0f 100644
--- a/arch/arm/src/sama5/sam_adc.c
+++ b/arch/arm/src/sama5/sam_adc.c
@@ -50,6 +50,8 @@
 #include <nuttx/config.h>
 
 #include <sys/types.h>
+#include <sys/ioctl.h>
+
 #include <stdio.h>
 #include <stdint.h>
 #include <stdbool.h>
@@ -1081,18 +1083,29 @@ static void sam_adc_rxint(struct adc_dev_s *dev, bool enable)
 
 static int sam_adc_ioctl(struct adc_dev_s *dev, int cmd, unsigned long arg)
 {
+  struct sam_adc_s *priv = (struct sam_adc_s *)dev->ad_priv;
+  int ret = OK;
+
   avdbg("cmd=%d arg=%ld\n", cmd, arg);
 
-  /* No ioctl commands supported:
-   *
-   * REVISIT:  Need to implement a ioctl to support software triggering
-   */
-
+  switch (cmd)
+    {
 #ifdef CONFIG_SAMA5_ADC_SWTRIG
-#  error Need an ioctl to perform software triggering
+      case ANIOC_TRIGGER: /* Software trigger */
+        {
+          sam_adc_putreg(priv, SAM_ADC_CR, ADC_CR_START); /* Start conversion */
+        }
+        break;
 #endif
 
-  return -ENOTTY;
+      /* Unsupported or invalid command */
+
+      default:
+        ret = -ENOTTY;
+        break;
+    }
+
+  return ret;
 }
 
 /****************************************************************************
diff --git a/include/nuttx/fs/ioctl.h b/include/nuttx/fs/ioctl.h
index 852113a4c0b..5c2fbb67b6b 100644
--- a/include/nuttx/fs/ioctl.h
+++ b/include/nuttx/fs/ioctl.h
@@ -219,7 +219,16 @@
 #define _SNIOCVALID(c)    (_IOC_TYPE(c)==_SNIOCBASE)
 #define _SNIOC(nr)        _IOC(_SNIOCBASE,nr)
 
-/* NuttX PWM ioctl definitions (see nuttx/pwm.h) ***************************/
+/* Nuttx Analog (DAC/ADC_ ioctl commands ************************************/
+
+#define _ANIOCVALID(c)    (_IOC_TYPE(c)==_ANIOCBASE)
+#define _ANIOC(nr)        _IOC(_ANIOCBASE,nr)
+
+#define ANIOC_TRIGGER     _ANIOC(0x0001)  /* Trigger one conversion
+                                           * IN: None
+                                           * OUT: None */
+
+/* NuttX PWM ioctl definitions (see nuttx/pwm.h) ****************************/
 
 #define _PWMIOCVALID(c)   (_IOC_TYPE(c)==_PWMIOCBASE)
 #define _PWMIOC(nr)       _IOC(_PWMIOCBASE,nr)