Added a nullHandler function to deal with blank line input.

SerialCommand.cpp

@@ -1,23 +1,24 @@
 /**
  * SerialCommand - A Wiring/Arduino library to tokenize and parse commands
  * received over a serial port.
- * 
+ *
  * Copyright (C) 2012 Stefan Rado
  * Copyright (C) 2011 Steven Cogswell <[email protected]>
  *                    http://husks.wordpress.com
- * 
- * Version 20120522
- * 
+ *
+ * Updated for blank line support, an alternate line terminator, and a
+ * non-printable character in the input buffer by DeKay, Feb 2014
+ *
  * This library is free software: you can redistribute it and/or modify
  * it under the terms of the GNU Lesser General Public License as published by
  * the Free Software Foundation, either version 3 of the License, or
  * (at your option) any later version.
- * 
+ *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU Lesser General Public License for more details.
- * 
+ *
  * You should have received a copy of the GNU General Public License
  * along with this library.  If not, see <http://www.gnu.org/licenses/>.
  */
@@ -30,7 +31,9 @@ SerialCommand::SerialCommand()
   : commandList(NULL),
     commandCount(0),
     defaultHandler(NULL),
+    nullHandler(NULL),
     term('\n'),           // default terminator for commands, newline character
+    term2('\r'),          // default alternate terminator for commands, carriage return character
     last(NULL)
 {
   strcpy(delim, " "); // strtok_r needs a null-terminated string
@@ -64,6 +67,13 @@ void SerialCommand::setDefaultHandler(void (*function)(const char *)) {
   defaultHandler = function;
 }
 
+/**
+ * This sets up a handler to be called in the event that the user hits enter on a
+ * blank line
+ */
+void SerialCommand::setNullHandler(void (*function)()) {
+  nullHandler = function;
+}
 
 /**
  * This checks the Serial stream for characters, and assembles them into a buffer.
@@ -77,7 +87,7 @@ void SerialCommand::readSerial() {
       Serial.print(inChar);   // Echo back to serial stream
     #endif
 
-    if (inChar == term) {     // Check for the terminator (default '\r') meaning end of command
+    if ((inChar == term) || (inChar == term2)) {  // Check for the terminators ('\n') or ('\r') meaning end of command
       #ifdef SERIALCOMMAND_DEBUG
         Serial.print("Received: ");
         Serial.println(buffer);
@@ -111,10 +121,16 @@ void SerialCommand::readSerial() {
         if (!matched && (defaultHandler != NULL)) {
           (*defaultHandler)(command);
         }
+      } else {
+        (*nullHandler)();
       }
       clearBuffer();
     }
-    else if (isprint(inChar)) {     // Only printable characters into the buffer
+    // Only printable characters into the buffer EXCEPT for 0x12.
+    // This is necessary to implement the WRD<0x12><0x4d> command used by
+    // WeeWx when talking to a Davis weather station. Note 0x4d is printable
+    // so it does not need an exception below.
+    else if (isprint(inChar) || (inChar == 0x12)) {
       if (bufPos < SERIALCOMMAND_BUFFER) {
         buffer[bufPos++] = inChar;  // Put character into buffer
         buffer[bufPos] = '\0';      // Null terminate

SerialCommand.h

@@ -6,7 +6,7 @@
  * Copyright (C) 2011 Steven Cogswell <[email protected]>
  *                    http://husks.wordpress.com
  * 
- * Version 20120522
+ * Updated for blank line support & an alternate line terminator by DeKay, Feb 2014
  * 
  * This library is free software: you can redistribute it and/or modify
  * it under the terms of the GNU Lesser General Public License as published by
@@ -47,6 +47,7 @@ class SerialCommand {
     SerialCommand();      // Constructor
     void addCommand(const char *command, void(*function)());  // Add a command to the processing dictionary.
     void setDefaultHandler(void (*function)(const char *));   // A handler to call when no valid command received.
+    void setNullHandler(void (*function)());      // A handler to call when empty command received.
 
     void readSerial();    // Main entry point.
     void clearBuffer();   // Clears the input buffer.
@@ -63,9 +64,12 @@ class SerialCommand {
 
     // Pointer to the default handler function
     void (*defaultHandler)(const char *);
+    // Pointer to the null handler function
+    void (*nullHandler)();
 
     char delim[2]; // null-terminated list of character to be used as delimeters for tokenizing (default " ")
     char term;     // Character that signals end of command (default '\n')
+    char term2;    // Alternate character that signals end of command (default '\r')
 
     char buffer[SERIALCOMMAND_BUFFER + 1]; // Buffer of stored characters while waiting for terminator character
     byte bufPos;                        // Current position in the buffer

examples/SerialCommandExample/SerialCommandExample.pde

@@ -1,6 +1,7 @@
 // Demo Code for SerialCommand Library
 // Steven Cogswell
 // May 2011
+// Updated for blank line support by DeKay, Feb 2014
 
 #include <SerialCommand.h>
 
@@ -20,6 +21,7 @@ void setup() {
   sCmd.addCommand("HELLO", sayHello);        // Echos the string argument back
   sCmd.addCommand("P",     processCommand);  // Converts two arguments to integers and echos them back
   sCmd.setDefaultHandler(unrecognized);      // Handler for command that isn't matched  (says "What?")
+  sCmd.setNullHandler(blankLine);            // Handler for a blank line  (says "No Input.")
   Serial.println("Ready");
 }
 
@@ -81,3 +83,8 @@ void processCommand() {
 void unrecognized(const char *command) {
   Serial.println("What?");
 }
+
+// This gets set as the null handler, and gets called a blank line is received.
+void blankLine() {
+  Serial.println("No input.");
+}

keywords.txt

@@ -10,6 +10,7 @@ SerialCommand KEYWORD1
 
 addCommand        KEYWORD2
 setDefaultHandler KEYWORD2
+setNullHandler    KEYWORD2
 readSerial        KEYWORD2
 clearBuffer       KEYWORD2
 next              KEYWORD2

readme.md

@@ -1,7 +1,7 @@
 SerialCommand
 =============
-A Wiring/Arduino library to tokenize and parse commands received over a serial port. 
+A Wiring/Arduino library to tokenize and parse commands received over a serial port.
 
 The original version of this library was written by [Steven Cogswell](http://husks.wordpress.com) (published May 23, 2011 in his blog post ["A Minimal Arduino Library for Processing Serial Commands"](http://husks.wordpress.com/2011/05/23/a-minimal-arduino-library-for-processing-serial-commands/)).
 
-This is a heavily modified version with smaller footprint and a cleaned up code by Stefan Rado.
+My changes are based on a heavily modified version with smaller footprint and cleaned up code by Stefan Rado.  They add support for a return entered on an empty line, a second line terminator, and the allowance of non-printable characters in the input buffer when necessary when talking to a Davis weather station.