Several fixes to the PIC32 USB device OUT path logic

git-svn-id: https://nuttx.svn.sourceforge.net/svnroot/nuttx/trunk@4451 7fd9a85b-ad96-42d3-883c-3090e2eb8679

apps/examples/usbterm/usbterm.h

@@ -132,6 +132,8 @@ struct usbterm_globals_s
   FILE     *instream;  /* Stream for incoming USB data */
   FILE     *outstream; /* Stream for outgoing USB data */
   pthread_t listener;  /* USB terminal listener thread */
+  bool      peer;      /* True: A peer is connected to the serial port on
+                        * the remote host */
 
   /* Buffers for incoming and outgoing data */
 

apps/examples/usbterm/usbterm_main.c

@@ -127,15 +127,27 @@ FAR void *usbterm_listener(FAR void *parameter)
   message("usbterm_listener: Waiting for remote input\n");
   for (;;)
     {
-      /* Display the prompt string on the remote USB serial connection */
+      /* Display the prompt string on the remote USB serial connection -- only
+       * if we know that there is someone listening at the other end.  The
+       * remote side must initiate the the conversation.
+       */
 
-      fputs("\rusbterm> ", g_usbterm.outstream);
-      fflush(g_usbterm.outstream);
+      if (g_usbterm.peer)
+        {
+          fputs("\rusbterm> ", g_usbterm.outstream);
+          fflush(g_usbterm.outstream);
+        }
 
      /* Get the next line of input from the remote USB serial connection */
 
       if (fgets(g_usbterm.inbuffer, CONFIG_EXAMPLES_USBTERM_BUFLEN, g_usbterm.instream))
         {
+          /* If we receive anything, then we can be assured that there is someone
+           * with the serial driver open on the remote host.
+           */
+
+          g_usbterm.peer = true;
+
           /* Echo the line on the local stdout */
 
           fputs(g_usbterm.inbuffer, stdout);
@@ -181,6 +193,10 @@ int MAIN_NAME(int argc, char *argv[])
   pthread_attr_t attr;
   int ret;
 
+  /* Initialize global data */
+
+  memset(&g_usbterm, 0, sizeof(struct usbterm_globals_s));
+
   /* Initialization of the USB hardware may be performed by logic external to
    * this test.
    */
@@ -324,9 +340,11 @@ int MAIN_NAME(int argc, char *argv[])
           return 1;
         }
 #endif
-      else
+      /* Is there anyone listening on the other end? */
+
+      else if (g_usbterm.peer)
         {
-          /* Send the line of input via USB */
+          /* Yes.. Send the line of input via USB */
 
           fputs(g_usbterm.outbuffer, g_usbterm.outstream);
 
@@ -335,6 +353,10 @@ int MAIN_NAME(int argc, char *argv[])
           fputs("\rusbterm> ", g_usbterm.outstream);
           fflush(g_usbterm.outstream);
         }
+      else
+        {
+          printf("Still waiting for remote peer.  Please try again later.\n", ret);
+        }
 
       /* If USB tracing is enabled, then dump all collected trace data to stdout */
 

nuttx/Documentation/NuttX.html

@@ -152,10 +152,11 @@
       to support a rich, multi-threaded development environment for deeply embedded
       processors.
     </p>
-      NON-GOALS: (1) It is not a goal to provide the rich level of OS
-      features like those provided with Linux.
-      Small footprint is more important than features.
-      Standard compliance is more important than small footprint.
+      NON-GOALS: (1) It is not a goal to provide the level of OS features like those provided by Linux.
+      In order to work with smaller MCUs, small footprint must be more important than an extensive feature set.
+      But standard compliance is more important than small footprint.
+      Surely a smaller RTOS could be produced by ignoring standards.
+      Think of NuttX is a tiny Linux work-alike with a much reduced feature set.
       (2) There is no MMU-based support for processes.
       At present, NuttX assumes a flat address space.
     </p>