Made keep-alive token a configuration option. Default (newline) tested with both repsnapper and pronterface.

Author: modmaker

bebopr.h

@@ -15,6 +15,7 @@ extern int bebopr_pre_init( void);
 // Configuration
 
 extern int config_e_axis_is_always_relative( void);
+extern char config_keep_alive_char( void);
 
 // determines stepper driver control
 extern int config_use_pololu_drivers( void);

bebopr_r2.c

@@ -324,3 +324,16 @@ int config_e_axis_is_always_relative( void)
 {
   return 0;
 }
+
+/*
+ *  Specify the character code that should be used for keep-alive messages.
+ *  This character should not disturb the communication.
+ *  Pronterface seems to accept most characters, but only a newline
+ *  does not disturb the program.
+ *  Repsnapper also accepts the newline without causing problems.
+ */
+char config_keep_alive_char( void)
+{
+  return '\n';
+}
+

comm.c

@@ -63,6 +63,7 @@ static void* comm_thread( void* arg)
   char pending_input;
   char pending_output;
   int prescaler = 0;
+  char keep_alive_char = config_keep_alive_char();
   /*
    * The data from the stdout pipe does not become available until
    * stdout is flushed. So the timer is set to a short cycle that
@@ -83,7 +84,7 @@ static void* comm_thread( void* arg)
     } else if (rc == 0 || (rc < 0 && errno == EINTR)) {
       // timeout, send dummy character to keep connection alive
       if (++prescaler > keep_alive_timeout / timeout) {
-        printf( "%c", 10);	// only safe code for pronterface !
+        printf( "%c", keep_alive_char);
         fprintf( stderr, "<KEEP ALIVE SENT>");
         prescaler = 0;
       }