GPS_UBLOX: fixed auto-config of baudrate

this fixes the setting of the baudrate on a uBlox that is configured
for 9600. It fixes the NMEA message to have a \r\n, plus sends the
NAV_SOL rate config before the NMEA baudrate config message.

This fixes issue #159

libraries/AP_GPS/AP_GPS_Auto.cpp

@@ -49,7 +49,9 @@ AP_GPS_Auto::read(void)
 	if (now - last_baud_change_ms > 1200) {
 		// its been more than 1.2 seconds without detection on this
 		// GPS - switch to another baud rate
-		_port->begin(pgm_read_dword(&baudrates[last_baud]), 256, 16);		
+		_baudrate = pgm_read_dword(&baudrates[last_baud]);
+		//hal.console->printf_P(PSTR("Setting GPS baudrate %u\n"), (unsigned)_baudrate);
+		_port->begin(_baudrate, 256, 16);		
 		last_baud++;
 		last_baud_change_ms = now;
 		if (last_baud == sizeof(baudrates) / sizeof(baudrates[0])) {
@@ -88,7 +90,14 @@ AP_GPS_Auto::_detect(void)
 
 	while (_port->available() > 0 && new_gps == NULL) {
 		uint8_t data = _port->read();
-		if (AP_GPS_UBLOX::_detect(data)) {
+		/*
+		  running a uBlox at less than 38400 will lead to packet
+		  corruption, as we can't receive the packets in the 200ms
+		  window for 5Hz fixes. The NMEA startup message should force
+		  the uBlox into 38400 no matter what rate it is configured
+		  for.
+		 */
+		if (_baudrate >= 38400 && AP_GPS_UBLOX::_detect(data)) {
 			hal.console->print_P(PSTR(" ublox "));
 			new_gps = new AP_GPS_UBLOX();
 		} 

libraries/AP_GPS/AP_GPS_UBLOX.h

@@ -15,14 +15,18 @@
 #include "GPS.h"
 
 /*
- *  try to put a UBlox into binary mode. This is in two parts. First we
- *  send a PUBX asking the UBlox to receive NMEA and UBX, and send UBX,
- *  with a baudrate of 38400. Then we send a UBX message setting rate 1
- *  for the NAV_SOL message. The setup of NAV_SOL is to cope with
- *  configurations where all UBX binary message types are disabled.
+ *  try to put a UBlox into binary mode. This is in two parts. 
+ *
+ * First we send a ubx binary message that enables the NAV_SOL message
+ * at rate 1. Then we send a NMEA message to set the baud rate to our
+ * desired rate. The reason for doing the NMEA message second is if we
+ * send it first the second message will be ignored for a baud rate
+ * change.
+ * The reason we need the NAV_SOL rate message at all is some uBlox
+ * modules are configured with all ubx binary messages off, which
+ * would mean we would never detect it.
  */
-
-#define UBLOX_SET_BINARY "$PUBX,41,1,0003,0001,38400,0*26\n\265\142\006\001\003\000\001\006\001\022\117"
+#define UBLOX_SET_BINARY "\265\142\006\001\003\000\001\006\001\022\117$PUBX,41,1,0003,0001,38400,0*26\r\n"
 
 class AP_GPS_UBLOX : public GPS
 {

libraries/AP_GPS/GPS.cpp

@@ -160,6 +160,7 @@ void GPS::_update_progstr(void)
 	if (nbytes > 16) {
 		nbytes = 16;
 	}
+	//hal.console->printf_P(PSTR("writing %u bytes\n"), (unsigned)nbytes);
 	_write_progstr_block(progstr_state.fs, q->pstr+q->ofs, nbytes);
 	q->ofs += nbytes;
 	if (q->ofs == q->size) {

libraries/AP_GPS/GPS.h

@@ -206,6 +206,9 @@ protected:
     // does this GPS support raw velocity numbers?
     bool _have_raw_velocity;
 
+	// detected baudrate
+	uint16_t _baudrate;
+
 private: