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Topic: Problem with passing AT commands to the 3G/GSM Module (SIM5218) (Read 4490 times) previous topic - next topic


Hi, i got a problem passing AT commands to the SIM Card of the 3G/GSM Module for Arduino.

Informations about the Module:
I bought it from Cooking Hacks:  http://www.cooking-hacks.com/3g-gprs-shield-for-arduino-3g-gps?___store=en&___from_store=es
Schematics : http://www.cooking-hacks.com/skin/frontend/default/cooking/pdf/3G_shield_schematic.pdf
And tutorial here:  http://www.cooking-hacks.com/documentation/tutorials/arduino-3g-gprs-gsm-gps

I received a SIM Card from Free Mobile (France), to test with the module, but when i set instructions via AT Commands (simple ones), nothing was answerred by the Module.
So, I checked the supply everywhere on the module, and I got:

Power Pins (Pinouts):

- 2.85V instead of 3.3V
- 4.65V instead of 5V
I want to let you know that Arduinos Mega i got are providing 4.85V, but i don't think it is a problem for the 3.3V regulators on the shield.

Then, i checked the supply provided to the camera connectors and i got 2.27V instead of 2.8V and 1.8V on the 1.8V so that is ok.

The last part which is a big issue here, is that i get a 0.5V supply input for the SIM_V pin instead of 1.8V or 3.3V. I'm kind of stuck here, i can't directly check on the SIM5218 Module, as pins are too tiny.

Do you have any idea where can be the problem knowing those informations?

Code Part:

I tried different set of commands as it is provided in the datasheet, with and without Carriage Return and Line Feed, but nothing happened.

Here is my starting code:

char income;

void setup ()


void loop () {

   // I tried to pass the command in different ways

    income= Serial3.read();

    income=Serial.read();  //Get the character coming from the terminal



I'm available for further informations if you need more details on tests I did.




I just retry this morning and I have 2.2V on VCC SIM supply, i'm now asking myself if it can comes from the SIM Card itself.

I'm not sure about Free Mobile SIM can answer AT Commands.. Do you have any suggestion on this?




Have you first attempted to send and receive an SMS message?  If so, was that successful?

I have both the Cooking Hacks gsm module and the Arduino gsm shield that comes with the Telefonica card.  I purchased two T-Mobile sim cards for my projects.

My Arduino gsm shield sends and receives sms perfectly with the TMobile card and I am fairly comfortable that voice calls will work as well.  The Cooking Hacks (CH) module I have came with a full kit (speaker, microphone, headset, power cord, etc).  The CH module had a much higher baud rate, so I was initially seeing noise in the serial screen until I realized I needed to go to the right baud rate.  The CH module is slower to connect to the network for sending and receiving sms, but it worked with the TMobile card.  After I was sure it could connect, I attempted a voice call.  That would not connect.  I suspect that I have the same issues you have, power limitations.  I am going to see if I can send more power to my CH Module.

I would love it if my Arduino GSM could do a video call like the CH module is supposed to do.

Sorry I couldn't answer your question...but know that you are not alone.


I worked all weekend on this and was able to get voice calls working using T-Mobile SIM card.  There are some things about the Cooking Hacks (CH) 3G/GSM/GPRS module that you have to know:  1) You can't just use the USB serial connection to power the Arduino and the CH GSM Module, you must additionally use a 5-9V power cord attached to the power adapter inlet on your Arduino Uno board; 2) The two jumper pins should be in USB mode before you send your sketch to the Arduino (otherwise you will have to disconnect the shield and transfer your sketch, then reattach it) once you are done transferring your sketch-put the jumpers in Arduino mode; 3) Before you start the serial port to initiate the sketch you must wait for the CH GSM board LED to be blinking.  If you try to send the AT commands while the LED is on stable (not blinking) or off completely, you will hang in AT send mode using the CH sketch or at AT+CREG? trying to authorized on the network.  WAIT for the blinking light.  I found that you can coax it on by starting and quickly closing the serial port...then wait and it will begin flashing, then fully start the sketch.

It appears that the T-Mobile SIM card does not support video calls.  I will get an AT&T card this week and try to get the video call feature working for the application I'm working on.


Hello 4Given,
Ditto on hanging at AT+CREG? with this CH 3G modem. Do you have a record of the on/off cycling that you used to "coax" on the modem serial port, before starting your sketch?

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