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[Reply #15 on:]

Hi there

I do actually have a very similar problem, that I haven't found the solution yet.
I'm trying to control a SIM900 mounted on a Efcom Pro (http://www.elecfreaks.com/wiki/index.php?title=EFCom_Pro_GPRS/GSM_Module) with my UNO. I sticked to the tutorial on said wiki and ended up with the following code (arduino 1.0.3):

Code:

#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()); 
 
}

Than hooked up the serial connection from the Efcom Pro to pins 2 and 3 and started my serial monitor and turned on the Efcom Pro. As expected the chip sent out some data upon turning on, but it looked like this: Ý Ý Ý Ý Ý Ý  .

Trying to communicate with it through AT commands did nothing at all, no reply. I see from the blinking on the Efcom Pro, that it has registered with the network, but it's not reachable through the serial connection.

Any suggestions?

I would look at the speed serial monitor of arduino ide.
que tambien este en 19200.

[Reply #16 on:]

Thanks, I checked that. It is set to  19200. The thing is, when I change the setting the strange characters change to other strange characters or disappear at all, but are never any readable text.

[Reply #17 on:]

are never any readable text.

...usually implies either a speed mismatch, or a line inversion.

However

but it looked like this: Ý Ý Ý Ý Ý Ý  .

looks more like the -1 that a serial read rturns if there is no data to read.

[Reply #18 on:]

are never any readable text.

...usually implies either a speed mismatch, or a line inversion.

I checked these speeds and matched them to the speed of the Efcom Pro (what it says in the product description... is there any way to check it?):

- serial port (in Windows hardware manager)
- serial monitor

Do I need to check in other places as well?

looks more like the -1 that a serial read rturns if there is no data to read.

The thing is, it sends this only when the chip is powered on, then it stops. So I interpret it as the "hello, i'm ready signal" of the chip...

[Reply #19 on:]

The problem persists, anyone got an idea?

I read somewhere else, that a inversion of the high and low might be a problem --> a pullup resistor might do the trick. I haven't had time so far to check this out, does anyone think, that this might do the trick?

[Reply #20 on:]

I am using this shield with a Arduino UNO and I have managed to get it to work using the code see below: I am running Arduino 1.0.4

I have the jumpers set to the default position: D3 is set to S_RX and D2 is set to S_TX

Code:

#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()); 
 
}

I am applying 6 V DC to the UNO as well as USB from the PC sending the serial commands.

I am having problems working out how to send a SMS using the Hardware Serial settings. What I want to be able to do is send an SMS message directly from the UNO code.  I can't work out the jumper settings.  for the GSM sheild.