Polling uBlox MAX-6Q - c

Question

I'm currently working on a HAB (High Altitude Balloon) project, and so far, all has gone swimmingly.
I'm using an Arduino uno R3 as my main controller for this project, however, I'm struggling with the GPS side of things here.
Follwing the fantastic tutorial at UK-HAS (http://ukhas.org.uk/guides:ublox6) I'm currently working with the uBlox MAX-6Q GPS module.
I've played around with the code supplied on the tutorial, and am in the process of testing with the following sketch:
#include <SoftwareSerial.h>
SoftwareSerial GPS(3,2);
byte gps_set_success = 0;
void setup()
{
Serial.begin(9600);
GPS.begin(9600);
GPS.print("$PUBX,41,1,0007,0003,4800,0*13\r\n");
GPS.begin(4800);
GPS.flush();
uint8_t setNav[] = {
0xB5, 0x62, 0x06, 0x24, 0x24, 0x00, 0xFF, 0xFF, 0x06, 0x03, 0x00, 0x00, 0x00, 0x00, 0x10, 0x27, 0x00, 0x00,
0x05, 0x00, 0xFA, 0x00, 0xFA, 0x00, 0x64, 0x00, 0x2C, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x16, 0xDC };
/*while(!gps_set_success)
{
sendUBX(setNav, sizeof(setNav)/sizeof(uint8_t));
gps_set_success = getUBX_ACK(setNav);
}*/
gps_set_success = 0;
GPS.println("$PUBX,40,GGA,0,0,0,0*5A");
GPS.println("$PUBX,40,GSA,0,0,0,0*4E");
GPS.println("$PUBX,40,RMC,0,0,0,0*47");
GPS.println("$PUBX,40,GSV,0,0,0,0*59");
GPS.println("$PUBX,40,VTG,0,0,0,0*5E");
GPS.println("$PUBX,40,GLL,0,0,0,0*5C");
}
void loop()
{
printGPSData();
delay(3000);
}
void printGPSData()
{
Serial.println("Polling: $PUBX,00*33");
GPS.println("$PUBX,00*33");
while (GPS.available())
{
if (GPS.available() > 0)
{
char c = GPS.read();
Serial.write(c);
}
}
Serial.println();
}
void sendUBX(uint8_t *MSG, uint8_t len)
{
for (int i = 0; i<len; i++)
{
GPS.write(MSG[i]);
Serial.print(MSG[i], HEX);
}
GPS.println();
}
boolean getUBX_ACK(uint8_t *MSG)
{
uint8_t b;
uint8_t ackByteID = 0;
uint8_t ackPacket[10];
unsigned long startTime = millis();
Serial.print(" * Reading ACK response: ");
ackPacket[0] = 0xB5;
ackPacket[1] = 0x62;
ackPacket[2] = 0x05;
ackPacket[3] = 0x01;
ackPacket[4] = 0x02;
ackPacket[5] = 0x00;
ackPacket[6] = MSG[2];
ackPacket[7] = MSG[3];
ackPacket[8] = 0;
ackPacket[9] = 0;
for (uint8_t i=2; i<8; i++)
{
ackPacket[8] = ackPacket[8] + ackPacket[i];
ackPacket[9] = ackPacket[9] + ackPacket[8];
}
while(1)
{
if (ackByteID > 9)
{
Serial.println("(SUCCESS!)");
return true;
}
if (millis() - startTime > 3000)
{
Serial.println("(FAILED!)");
return false;
}
if (GPS.available())
{
b = GPS.read();
if (b == ackPacket[ackByteID])
{
ackByteID++;
Serial.print(b,HEX);
}
else
{
ackByteID = 0;
}
}
}
}
I've been struggling with 2 issues here. I'm hitting the timeout in the getUBX_ACK method, thus meaning, no response from the GPS module to confirm the setting change. This isn't currently crucial as if need be, I can configure this through uCenter, and add a battery to preserve the settings.
However, the main issue I am facing is when I run this sketch with the setNav block in the setup commented out, I am able to turn off all the automatic NMEA sentences, and poll the module, but upon polling, I am greeted with the following:
Polling: $PUBX,00*33
followed by a number of invalid characters. (Rectangles)
I've checked baud rates stop bits, parity etc. along with the actual data line connections, but cannot seem to find the source of this. It suggests bad data lines/encoding/ to me, but I was wondering if this was something anybody else had ever experienced?
EDIT:
So, after more testing, it would appear that the SoftwareSerial library is NOT at fault here. I tried first, writing to an OpenLog using the SoftwareSerial GPS ipput, and then by hooking the GPS Tx directly into the OpenLog Rx. Same story. Opening the resulting file in Notepad++ yeilds a lovely bunch of 'NULL' characters. I can only presume something in the way the GPS is configured at runtime is causing a problem.
Bypassing the Arduino, and turning off the sentences and polling the GPS directly through serial works with no problems, the data is returned perfectly.

Answer 1

So, I'm feeling a bit daft here, there is an issue, but not with the GPS, I'll ask as a seperate question. It would appear I'm having problems with the SoftwareSerial library.
The SoftwareSerial library cannot use multiple soft serial ports at the same time, it would appear that despite many suggestions otherwise, I cannot switch between sof serial ports, as I am unable to begin() the second port, it would appear that the port first declared is to be unusable.