GPRS+GPS communication - gps

Question

My project is using GPRS and GPS shield. My board has 2 UART ports so there will be no problem when I use the 2 shields. My codes for both shields works fine alone, but when I already integrated the two in one board, the code for the GPS doesnt continue (GPRS works), its like stuck in this command
ptr = strstr(GPS_data, "$GPGGA"); //search GPGGA String
but this command runs perfectly if I only use the GPS shield alone with the board. Im using 2 baud rates, 57600 for GPRS and 9600 for the GPS. What could possibly be the problem for this? Thank you!
This is a part of my GPS code.
void SEND_data()
{
digitalWrite(gpsPin, HIGH);
Serial1.begin(9600); //GPS shield communication
pinMode(TX1, OUTPUT);
digitalWrite(TX1, HIGH);
Serial1.write(Serial1.read());
while(!ptr)
{
while(Serial1.available())
delay(10);
{
GPS_data[i]=Serial1.read(); //output of the GPS
i++;
j=0;
delay(10);
}
ptr = strstr(GPS_data,"$GPGGA"); //search GPGGA String
digitalWrite(gogoPin, HIGH);
}
digitalWrite(sendPin, HIGH);
My problem is that digitalWrite(sendPin, HIGH) above doesnt light anymore, so basically the running code stops in the part of the digitalWrite(gogoPin, HIGH); just above the bracket ({).

Answer 1

Your problem seems to be in fact a shield stacking problem. If you have bought your shields from same place as your Arduino board this is the case.
Seesntially, you have connected 2 devices to TX/RX pins which is not supported. Following post should explain it better Arduino Uno RX TX Pins.
Generally, in order to make it work, you have to rewire one of the shelds to use different pins and use SoftwareSerial library to communicate with them. This also means you cannot use stacking capability unless physically modifying one of your shields.
On a side note, you might want to use Electronics StackExchange site for futher questions regarding Arduino.