Use this sketch:

#include “SIM900.h”
#include
#include “GSM.h”

//#define _GSM_TXPIN_ 4
//#define _GSM_RXPIN_ 5

//If not used, is better to exclude the HTTP library,
//for RAM saving.
//If your sketch reboots itself proprably you have finished,
//your memory available.
//#include “inetGSM.h”

//If you want to use the Arduino functions to manage SMS, uncomment the lines below.
#include “sms.h”
SMSGSM sms;

//GSM Shield for Arduino
//www.open-electronics.org
//this code is based on the example of Arduino Labs.

//Simple sketch to send and receive SMS.

char msg[200];
int numdata;

void setup()
{

//Serial connection.
Serial.begin(9600);
Serial.println(“GSM Shield testing.”);
//Start configuration of shield with baudrate.
//For http uses is raccomanded to use 4800 or slower.
if (gsm.begin(9600))
Serial.println(“\nstatus=READY”);
else Serial.println(“\nstatus=IDLE”);

//Enable this two lines if you want to send an SMS.
if (sms.SendSMS(“+552299664351″, “Arduino SMS”))
Serial.println(“\nSMS sent OK”);

};

void loop()
{
char smsbuffer[160];
char n[20];
//Read if there are messages on SIM card and print them.
if(gsm.readSMS(smsbuffer, 160, n, 20))
{
Serial.println(n);
Serial.println(smsbuffer);
}
delay(1000);
};

always return:
GSM Shield testing.
DB:NO RESP
DB:NO RESP
DB:NO RESP
ERROR: SIM900 doesn’t answer. Check power and serial pins in GSM.cpp

status=IDLE
DEBUG:SMS TEST

SMS sent OK

But don’t send.

and in GSM.cpp use:
#define _GSM_TXPIN_ 4
#define _GSM_RXPIN_ 5

library use:

SoftwareSerial and SIM900IDE100

Thanks.

Is it possible to make charges to this unit so we can test higher currents of aprox 10amps @ 24vdc

Thanks

It says in datasheet that the power supply should be 9~20V, so if i power up my arduino with a 6V battery it wont work ?

Because it also says it is compatible with arduino.

Or do i have to power up my arduino with a 9~20V battery instead? Because that wont be any good for me…

I just got myself a beautiful colorduino, but what if I want to drive high power (let’s say 10w) LEDs?

How exactly should I connect transistors between the 2X16pin socket and my 32 ‘big’ wires?

Thanks for helping me