EFCom GPRS/GSM Shield

Question

I have an EFCom GPRS/GSM Shield http://www.elecfreaks.com/wiki/index.php?title=EFCom_GPRS/GSM_Shield and I am using it with a mega 2560. The problem is that the code in the wiki page

//Serial Relay - Arduino will patch a 
//serial link between the computer and the GPRS Shield 
//at 19200 bps 8-N-1 
//Computer is connected to Hardware UART 
//GPRS Shield is connected to the Software UART 
#include <SoftwareSerial.h> 
SoftwareSerial mySerial(2, 3); 
void setup() { 
 mySerial.begin(19200); // the GPRS baud rate
 Serial.begin(19200); // the GPRS baud rate 
} 
void loop() { 
 if (mySerial.available())
 Serial.write(mySerial.read()); 
 if (Serial.available())
 mySerial.write(Serial.read()); 
}

makes use of software serial but mega 2560 cannot use software serial on pin 2, as in the arduino reference, thus I changed the pins to 50 and 51 and used external female-male headers to connect s_tx to pin 50 "rx" , and s_rx to pin 51 "tx", still no response with the AT command...

code after update is :

#include <SoftwareSerial.h> 
SoftwareSerial mySerial(50, 51); 
void setup() { 
 mySerial.begin(19200); // the GPRS baud rate 
 Serial.begin(19200); // the GPRS baud rate 
}
void loop() { 
 if (mySerial.available())
 Serial.write(mySerial.read()); 
 if (Serial.available())
 mySerial.write(Serial.read()); 
}

Note that I am using the Arduino IDE serial monitor.

Answer 1

Try to connect "Pin RX on Mega to Pin RX on Shield" an "Pin TX on Mega to Pin TX on Shield":

• Pin 50 (Rx) on Mega <==> Pin 2 GSM Rx on Shield
• Pin 51 (Tx) on Mega <==> Pin 3 GSM Tx on Shield

I use an Geeetech Shield with a Mega 2560 and connect RX to Rx and TX to TX. Works fine.

Another solution is to use Serial1 instead of using SoftwareSerial ...

First connect:

• Pin 19 (Rx1) on Mega <==> Pin 2 GSM Rx on Shield
• Pin 18 (Tx1) on Mega <==> Pin 3 GSM Tx on Shield

 //Serial Relay
 unsigned char buffer[64]; // buffer array for data receive over serial port
 int count=0; // counter for buffer array

void setup()
{
 Serial1.begin(19200);
 Serial.begin(19200);
}
void loop()
{
 if (Serial1.available())
 {
 while(Serial1.available())
 {
 buffer[count++]=Serial1.read();
 if(count == 64)break;
 }
 Serial.write(buffer,count);
 clearBufferArray();
 count = 0;
 }
 if (Serial.available())
 Serial1.write(Serial.read());
}
void clearBufferArray()
{
 for (int i=0; i<count;i++)
 {
 buffer[i]=NULL;
 }
}

You can use a Arduino IDE's Serial Monitor, Serial Terminals(sscom32) or Bray++ Terminal to send AT commands to the Shield, communicate with it.

I hope this information is helpful.