diff --git a/arch/arm/src/stm32/stm32_pwm.c b/arch/arm/src/stm32/stm32_pwm.c
index 1e3f4f07d6..420537ebb6 100644
--- a/arch/arm/src/stm32/stm32_pwm.c
+++ b/arch/arm/src/stm32/stm32_pwm.c
@@ -70,6 +70,7 @@
  * Pre-processor Definitions
  ****************************************************************************/
 /* Debug ********************************************************************/
+/* Non-standard debug that may be enabled just for testing PWM */
 
 #ifdef CONFIG_DEBUG_PWM
 #  define pwmdbg    dbg
@@ -434,10 +435,13 @@ static int pwm_start(FAR struct pwm_lowerhalf_s *dev, FAR const struct pwm_info_
   uint16_t ocmode1;
   uint16_t ocmode2;
 
+  DEBUGASSERT(priv != NULL && info != NULL);
+
   pwmvdbg("TIM%d channel: %d frequency: %d duty: %08x\n",
           priv->timid, priv->channel, info->frequency, info->duty);
+  DEBUGASSERT(info->frequency > 0 && info->duty > 0 && info->duty < uitoub16(100));
 
-  /* Caculate optimal values for the timer prescaler and for the timer reload
+  /* Calculate optimal values for the timer prescaler and for the timer reload
    * register.  If' frequency' is the desired frequency, then
    *
    *   reload = timclk / frequency
diff --git a/configs/stm3240g-eval/README.txt b/configs/stm3240g-eval/README.txt
index 4fcc63938e..ac3ebb1033 100755
--- a/configs/stm3240g-eval/README.txt
+++ b/configs/stm3240g-eval/README.txt
@@ -521,3 +521,9 @@ Where <subdir> is one of the following:
     CONFIG_NSH_IPADDR=(10<<24|0<<16|0<<8|2)   : Target IP address 10.0.0.2
     CONFIG_NSH_DRIPADDR=(10<<24|0<<16|0<<8|1) : Host IP address 10.0.0.1
 
+    NOTE:  This example assumes that a network is connected.  During its
+    initialization, it will try to negotiate the link speed.  If you have
+    no network connected when you reset the board, there will be a long
+    delay (maybe 30 seconds?) before anything happens.  That is the timeout
+    before the networking finally gives up and decides that no network is
+    available.
diff --git a/configs/stm3240g-eval/include/board.h b/configs/stm3240g-eval/include/board.h
index ba1016910a..9ae54a4d02 100755
--- a/configs/stm3240g-eval/include/board.h
+++ b/configs/stm3240g-eval/include/board.h
@@ -274,7 +274,7 @@
  * FSMC must be disabled in this case!
  */
 
-#define GPIO_TIM4_CH2 GPIO_TIM4_CH2_1
+#define GPIO_TIM4_CH2 GPIO_TIM4_CH2_2
 
 /************************************************************************************
  * Public Data
diff --git a/drivers/pwm.c b/drivers/pwm.c
index 15447e9bec..455e727061 100644
--- a/drivers/pwm.c
+++ b/drivers/pwm.c
@@ -66,6 +66,20 @@
 /****************************************************************************
  * Pre-processor Definitions
  ****************************************************************************/
+/* Debug ********************************************************************/
+/* Non-standard debug that may be enabled just for testing PWM */
+
+#ifdef CONFIG_DEBUG_PWM
+#  define pwmdbg    dbg
+#  define pwmvdbg   vdbg
+#  define pwmlldbg  lldbg
+#  define pwmllvdbg llvdbg
+#else
+#  define pwmdbg(x...)
+#  define pwmvdbg(x...)
+#  define pwmlldbg(x...)
+#  define pwmllvdbg(x...)
+#endif
 
 /****************************************************************************
  * Private Type Definitions
@@ -128,6 +142,8 @@ static int pwm_open(FAR struct file *filep)
   uint8_t                     tmp;
   int                         ret;
 
+  pwmvdbg("crefs: %d\n", upper->crefs);
+
   /* Get exclusive access to the device structures */
 
   ret = sem_wait(&upper->sem);
@@ -159,6 +175,9 @@ static int pwm_open(FAR struct file *filep)
 
       /* Yes.. perform one time hardware initialization. */
 
+      DEBUGASSERT(lower->ops->setup != NULL);
+      pwmvdbg("calling setup\n");
+
       ret = lower->ops->setup(lower);
       if (ret < 0)
         {
@@ -192,6 +211,8 @@ static int pwm_close(FAR struct file *filep)
   FAR struct pwm_upperhalf_s *upper = inode->i_private;
   int                         ret;
 
+  pwmvdbg("crefs: %d\n", upper->crefs);
+
   /* Get exclusive access to the device structures */
 
   ret = sem_wait(&upper->sem);
@@ -219,6 +240,9 @@ static int pwm_close(FAR struct file *filep)
 
       /* Disable the PWM device */
 
+      DEBUGASSERT(lower->ops->shutdown != NULL);
+      pwmvdbg("calling shutdown: %d\n");
+
       lower->ops->shutdown(lower);
     }
   ret = OK;
@@ -275,6 +299,8 @@ static int pwm_ioctl(FAR struct file *filep, int cmd, unsigned long arg)
 
   /* Handle built-in ioctl commands */
 
+  pwmvdbg("cmd: %d arg: %ld\n", cmd, arg);
+
   switch (cmd)
     {
       /* PWMIOC_SETCHARACTERISTICS - Set the characteristics of the next pulsed
@@ -290,6 +316,11 @@ static int pwm_ioctl(FAR struct file *filep, int cmd, unsigned long arg)
       case PWMIOC_SETCHARACTERISTICS:
         {
           FAR const struct pwm_info_s *info = (FAR const struct pwm_info_s*)((uintptr_t)arg);
+          DEBUGASSERT(info != NULL && lower->ops->start != NULL);
+
+          pwmvdbg("PWMIOC_SETCHARACTERISTICS frequency: %d duty: %08x started: %d\n",
+                  info->frequency, info->duty, upper->started);
+
           memcpy(&upper->info, info, sizeof(struct pwm_info_s));
           if (upper->started)
             {
@@ -308,7 +339,11 @@ static int pwm_ioctl(FAR struct file *filep, int cmd, unsigned long arg)
       case PWMIOC_GETCHARACTERISTICS:
         {
           FAR struct pwm_info_s *info = (FAR struct pwm_info_s*)((uintptr_t)arg);
+          DEBUGASSERT(info != NULL);
+
           memcpy(info, &upper->info, sizeof(struct pwm_info_s));
+          pwmvdbg("PWMIOC_GETCHARACTERISTICS frequency: %d duty: %08x\n",
+                  info->frequency, info->duty);
         }
         break;
 
@@ -320,6 +355,11 @@ static int pwm_ioctl(FAR struct file *filep, int cmd, unsigned long arg)
 
       case PWMIOC_START:
         {
+          pwmvdbg("PWMIOC_START frequency: %d duty: %08x started: %d\n",
+                  upper->info.frequency, upper->info.duty, upper->started);
+
+          DEBUGASSERT(lower->ops->start != NULL);
+
           if (!upper->started)
             {
               ret = lower->ops->start(lower, &upper->info);
@@ -335,6 +375,9 @@ static int pwm_ioctl(FAR struct file *filep, int cmd, unsigned long arg)
 
       case PWMIOC_STOP:
         {
+          pwmvdbg("PWMIOC_STOP: started: %d\n", upper->started);
+          DEBUGASSERT(lower->ops->stop != NULL);
+
           if (upper->started)
             {
               ret = lower->ops->stop(lower);
@@ -347,6 +390,8 @@ static int pwm_ioctl(FAR struct file *filep, int cmd, unsigned long arg)
 
       default:
         {
+          pwmvdbg("Forwarding unrecognized cmd: %d arg: %ld\n", cmd, arg);
+          DEBUGASSERT(lower->ops->ioctl != NULL);
           ret = lower->ops->ioctl(lower, cmd, arg);
         }
         break;
@@ -392,6 +437,7 @@ int pwm_register(FAR const char *path, FAR struct pwm_lowerhalf_s *dev)
   upper = (FAR struct pwm_upperhalf_s *)zalloc(sizeof(struct pwm_upperhalf_s));
   if (!upper)
     {
+      pwmdbg("Allocation failed\n");
       return -ENOMEM;
     }
 
@@ -402,8 +448,8 @@ int pwm_register(FAR const char *path, FAR struct pwm_lowerhalf_s *dev)
 
   /* Register the PWM device */
 
-  vdbg("Registering %s\n", path);
-  return register_driver(path, &g_pwmops, 0666, dev);
+  pwmvdbg("Registering %s\n", path);
+  return register_driver(path, &g_pwmops, 0666, upper);
 }
 
 #endif /* CONFIG_PWM */