The previous initialisation strategy for auto-detection doesn't play well with the way APM uses the GPS.

Switch to subclassing GPS and manipulating a global pointer.  Update the test program so that it works again.

git-svn-id: https://arducopter.googlecode.com/svn/trunk@673 f9c3cf11-9bcb-44bc-f272-b75c42450872

libraries/AP_GPS/AP_GPS_Auto.cpp

@@ -10,8 +10,18 @@
 
 static unsigned int	baudrates[] = {38400U, 57600U, 9600U, 4800U};
 
-GPS *
+void
-AP_GPS_Auto::detect(void)
+AP_GPS_Auto::init(void)
+{
+}
+
+//
+// Called the first time that a client tries to kick the GPS to update.
+//
+// We detect the real GPS, then update the pointer we have been called through
+// and return.
+void
+AP_GPS_Auto::update(void)
 {
 	GPS		*gps;
 	int		i;
@@ -20,10 +30,21 @@ AP_GPS_Auto::detect(void)
 	for (;;) {
 		// loop through possible baudrates
 		for (i = 0; i < (sizeof(baudrates) / sizeof(baudrates[0])); i++) {
-			printf("autodetect at %d:%u\n", i, baudrates[i]);
+			printf("GPS autodetect at %d:%u\n", i, baudrates[i]);
 			_port->begin(baudrates[i]);
-			if (NULL != (gps = _detect()))
+			if (NULL != (gps = _detect())) {
-				return(gps);
+				// make the detected GPS the default
+				*_gps = gps;
+				
+				// configure the detected GPS and run one update
+				gps->print_errors = true;	// XXX
+				gps->init();
+				gps->update();
+
+				// drop back to our caller - subsequent calls through
+				// the global will not come here
+				return;
+			}
 		}
 	}
 }
@@ -129,12 +150,6 @@ AP_GPS_Auto::_detect(void)
 			break;
 		}
 	}
-
-	// If we detected a GPS, call its init routine
-	if (NULL != gps) {
-		gps->print_errors = true;	// XXX
-		gps->init();
-	}
 	return(gps);
 }
 

libraries/AP_GPS/AP_GPS_Auto.h

@@ -9,7 +9,7 @@
 #include <GPS.h>
 #include <FastSerial.h>
 
-class AP_GPS_Auto
+class AP_GPS_Auto : public GPS
 {
 public:
 	/// Constructor
@@ -21,17 +21,26 @@ public:
 	/// @param	ptr		Pointer to a GPS * that will be fixed up by ::init
 	///					when the GPS type has been detected.
 	///
-	AP_GPS_Auto(FastSerial *port = NULL) : _port(port)	{};
+	AP_GPS_Auto(FastSerial *port, GPS **gps) : 
+		_port(port),
+		_gps(gps)
+	{};
+
+	void		init(void);
 
 	/// Detect and initialise the attached GPS unit.  Returns a
 	/// pointer to the allocated & initialised GPS driver.
 	///
-	GPS		*detect(void);
+	void		update(void);
 
 private:
 	/// Serial port connected to the GPS.
 	FastSerial	*_port;
 
+	/// global GPS driver pointer, updated by auto-detection
+	///
+	GPS			**_gps;
+
 	/// low-level auto-detect routine
 	///
 	GPS			*_detect(void);

libraries/AP_GPS/examples/GPS_AUTO_test/GPS_AUTO_test.pde

@@ -4,23 +4,30 @@
 
 #include <FastSerial.h>
 #include <AP_GPS.h>
+#include <stdlib.h>
 
 FastSerialPort0(Serial);
 FastSerialPort1(Serial1);
 
 GPS	    *gps;
-AP_GPS_Auto GPS(&Serial1);
+AP_GPS_Auto GPS(&Serial1, &gps);
 
 #define T6 1000000
 #define T7 10000000
 
+void * operator new(size_t size) 
+{
+	return(calloc(size, 1));
+}
+
 void setup()
 {
 	Serial.begin(38400);
 	Serial1.begin(38400);
 
 	Serial.println("GPS AUTO library test");
-	gps = GPS.detect();		 // GPS Initialization
+	gps = &GPS;
+	gps->init();
 	delay(1000);
 }
 void loop()