Parallax GPS module help

DragonRiderLT

Hello,

So, I am currently trying to interface an arduino with a Parallax GPS module. This module only has one serial communication line, whereas the arduino needs two. The module also has a Smart Mode so that when a command signal is sent, a specific byte(s) is sent back. To overcome the one line problem, I am using an AND gate to enable reading and writing only when I want to read or write.

What I'm doing with this makes complete sense in my head, but for some reason the GPS module only responds with 0's. The AND gate is fast enough to be used in this scenario; I've tested it with only reading.

Here is the data sheet for the GPS module: http://www.parallax.com/dl/docs/prod/acc/gpsreceivermanual1.0.pdf

Here is my code:

#include <SoftwareSerial.h>


SoftwareSerial mySerial(10, 11); // RX, TX




// AND gates are fast enough for 4800 baud rate!


int readPin = 2;
int writePin = 3;


int incomingByte;
int message;


byte zero = 0x00;
byte one = 0x01;
byte two = 0x02;
byte nine = 0x09;


void setup()  {
  
  pinMode(readPin, OUTPUT);
  pinMode(writePin, OUTPUT);
  
  Serial.begin(9600);
  
  mySerial.begin(4800);  
}


void loop()  {  
    
    digitalWrite(writePin, HIGH);  //enable the write gate
    mySerial.write("!GPS");
    mySerial.write(two);
    digitalWrite(writePin, LOW);
    
  
    digitalWrite(readPin, HIGH);  //enable the read gate
    Serial.flush();
    if (mySerial.available())  {
      incomingByte = mySerial.read();
      Serial.println(incomingByte);
    }
    digitalWrite(readPin, LOW);


  
}

Below is a schematic:

kwinn

What unit are you using?

Franklin

http://playground.arduino.cc/Tutorials/GPS
http://dangerousprototypes.com/2011/05/07/parallax-gps-arduino/

DragonRiderLT

I am using the Arduino Duemnilanove with an ATMega 328.

Thank you for the rescources, but I have already seen these. I am in particular interested in the Smart Mode feature. Why won't it recognize the commands I'm giving it?

Franklin

Try just putting a 10K current limiting resistor between the tx and rx of the Arduino and see what you get. Somewhere I saw this done in a document but I can't find it now that I need it.

DragonRiderLT

The resistor did not seem to do anything.

It's strange because apparently the GPS module is sending data, but it is nothing but 0's, even when I request non-numeric data.