Show Posts
Pages: [1] 2
1  Products / Arduino GSM Shield / GSM Shield powering on: July 23, 2013, 07:11:25 am

I have the ITCOMSAT 1.1 GSM Shield, and I'm trying to use it with Arduino Pro Mini, so not as a shield.
I noticed that if I try to send some data by httpPost once every 20 seconds, with the arduino pro mini powered through USB, one requests makes it and the next one, not. I assume that the SIM900 simply doesn't have enough power.

Also, if disconnect the arduino from USB and connect 12.3V to RAW and GND (rated max. 2.5 A), (and connect RAW, GND, and VIN pins from Arduino to the corresponding pins on the shield (as if it was UNO), the SIM900 turns off. This is very weird to me.

Can you help me power the shield properly?

Thanks a lot!

EDIT: I changed the time interval to 40s and now it's all ok. But I still need to send some sample data every 10 seconds...
2  Products / Arduino GSM Shield / Problems with starting up the GSM Module on: July 11, 2013, 09:53:25 am

I try to make my ICOMSAT 1.1 gsm shield work. I can't get it on. Output from this code:

#include "SIM900.h"
#include <SoftwareSerial.h>
#include "sms.h"

char number[]="+40741405354";
void setup()
if (gsm.begin(2400))
sms.SendSMS(number,"Ce fai maci?");
void loop()


Trying to force the baud-rate to 9600

ERROR: SIM900 doesn't answer. Check power and serial pins in GSM.cpp


I use this library:

And the piece of this library that sends me that error is:

for (cont=0; cont<3; cont++){
if (AT_RESP_ERR_NO_RESP == SendATCmdWaitResp("AT", 500, 100, "OK", 5)&&!turnedON) { //check power
    // there is no response => turn on the module
#ifdef DEBUG_ON
Serial.println("DB:NO RESP");
// generate turn on pulse
digitalWrite(GSM_ON, HIGH);
digitalWrite(GSM_ON, LOW);
#ifdef DEBUG_ON

if (AT_RESP_OK == SendATCmdWaitResp("AT", 500, 100, "OK", 5)){
#ifdef DEBUG_ON
Serial.println("DB:CORRECT BR");
Serial.println("Trying to force the baud-rate to 9600\n");
for (int i=0;i<8;i++){
switch (i) {
case 0:
case 1:
case 2:
case 3:
case 4:
case 5:
case 6:
case 7:
Serial.println("ERROR: SIM900 doesn't answer. Check power and serial pins in GSM.cpp");
return 0;

I tried with Arduino Pro Mini and Arduino Uno and got the same result.

Thanks a lot!
3  Products / Arduino GSM Shield / How to wire GPRS Shield on: July 11, 2013, 04:34:18 am

I have the ICOMSAT v1.1 GSM shield made for Arduino Uno. I want to wire it to work with Arduino Pro Mini.
How do I power it? Because if i give it 12 V where Uno's Vin pin woould be, it doesn't start. Also, do I need to press the button every time in order to start up the SIM900?

4  Using Arduino / Networking, Protocols, and Devices / Re: Weird problem on: July 09, 2013, 05:42:08 am
Thank you for the answers!
I had a lot of strings printed through Serial for debug purposes, and I just put them into Flash memory with F()
It works perfect now.. (for the moment).

OFFTOPIC: It's a little frustrating with all these limitations... Is there a list with microcontrollers that are compatible with arduino bootloader?
5  Using Arduino / Networking, Protocols, and Devices / Re: Weird problem on: July 09, 2013, 05:06:06 am
I forgot to mention: the board resets ~10 times right after the first Serial.println() when i open the COM port in Visual Studio.
I'll try what you said and come back with an answer.
6  Using Arduino / Networking, Protocols, and Devices / Weird problem on: July 09, 2013, 04:44:22 am

I have a strange error with my problem. I wrote the code for an XBee and SD card, and now, when adding the one for Adafruit GPS, the board acts very strange. If i comment some function declarations, then it works. It seems that it's too much code in my project, but it is only 77%. Anyone had this problem before?

7  Using Arduino / Networking, Protocols, and Devices / Re: GPS - to move or not to move..? on: July 09, 2013, 12:26:46 am
So this error is the same at all GPS devices at the same time? I mean, can I just use this formula:
trueDeviceLocation = reportedDeviceLocation - (reportedGPSLocation - knownGPSLocation)
..and then check if the coordinates are the same:
if(previousTrueDeviceLocation == trueDeviceLocation) v = 0;

8  Using Arduino / Networking, Protocols, and Devices / GPS - to move or not to move..? on: July 08, 2013, 10:29:48 pm

I have the Adafruit Ultimate GPS, and I use their official library. I put the sensor somewhere outside, and I received speeds between 0.2-1.2 knots. I noticed that the coordinates where slightly changing (only the minutes) despite the fact that my module didn;t move at all.
How can I solve this problem from code? (i think that the change in coordinates depends on the gps precision, so i have to cancel it somehow)

Thanks a lot!
9  Using Arduino / General Electronics / Re: Low battery alert on: July 02, 2013, 12:21:09 am
Could you explain me why? I was thinking to use a NPN transistor to control if current flows from collector (Vcc) to emitter (GND)...
10  Using Arduino / General Electronics / Low battery alert on: July 01, 2013, 11:58:44 pm
So i need to know when my remote device ran out of battery. One solution I found here was the voltage divider: 2 series resistors from Vcc to GND and an analogRead() pin between them.

However, i also need long battery life, and this solution would drain it too quickly. If I connect a transistor in series with these two resistors, and the base to a digitalWrite() pin, would it do the trick? In that way I could activate the connection from the code, only when I need it - like an interrogation.

I've also read about another solution - to let the uprocessor to read the input voltage, but it was unclear somehow.
11  Using Arduino / Project Guidance / Re: Devices that can work with arduino on: June 27, 2013, 10:01:14 am
Thanks for the replies!

I am working on a data logger project: multiple (endpoint API) XBee's with ArduinoProMini's sending sensor data to the coordinator XBee in API mode.

Until here it's all simple. After that, i have two options: either i use an Android stick and attach to it a Sparkfun USB to Serial (to communicate with the coordinator API XBee) and a USB GPRS to act as a web server (don't know how I'll actually do it, because i'll need an usb hub for the two devices... but in theory it should work) smiley-grin

On the other hand I could send the data to an arduino (instead of Android Stick), and attach to it a GPRS or WiFi (their prices kill me) module and make it act as a web server.

Do you think it's possible (and realizable) to make a XBee API to talk via the usb hub + usb to serial with the Android stick?
What adventages would each option have?

Thanks again!
12  Using Arduino / Project Guidance / Devices that can work with arduino on: June 26, 2013, 08:45:56 am
I'm working on a project and in order to cut down costs i buy the pieces from china.
There are very cheap products, but the documentation is not in english. My question is: how can i know what type of modules can work with arduino? I mean.. everything that has pins is good?

For example, i need to make my Pro Mini board a web server. What wifi module from here could do the job?

Thanks a lot!
13  Using Arduino / Project Guidance / Re: A little help with my LF robot on: March 11, 2013, 11:54:01 pm
Thx, again!

So I wanted to fix the wheels directly to the motor axis.. but I realised that they would turn too fast and not have enough torque. I know that the voltage gives the speed of the motor, and the current passing throught it, the torque.

Is there a way to increase current, but, at the same time to decrease the voltage? Or do I have to use a gearing system (which I don't know to build and would increase the costs significantly)
14  Using Arduino / Project Guidance / Re: A little help with my LF robot on: March 10, 2013, 05:22:38 am
Hei! Thanks a lot for your answer. I still have a few questions, though.

1. What does this mean, in the datasheet of the sonar?

" The module is not suggested to connect directly to electric, if connected
electric, the GND terminal should be connected the module first, otherwise,
it will affect the normal work of the module. "

2. I only know the voltage rating of the motors (6V - they are from a cassette player). Is there a way I can measure the current they draw? If I measure their resistance with a multimeter, I=U/R will give me the drawn current?

3. When I connect the sonar directly to arduino, should I still use the capacitor in parallel with it? And are the other capacitors placed correctly?


15  Using Arduino / Project Guidance / A little help with my LF robot on: March 07, 2013, 09:11:45 pm
Ok, so this is my first project both with electronics and arduino. I'm working at a line follower robot. I use 5 IR sensors (phototransistor + led), 2 motors (differential drive), and 1 motor driver. It also needs to avoid obstacles, so I put a 4-pin proximity sensor, like .
For power supply, I think I'll use one 9V battery to power the Arduino (Uno), and a 4-pack of 1.5V (=6V) batteries to power the motors and the distance sensor. This is my schematic:

Uploaded with

What do you suggest:

1. What voltages do sonars like that usually work? Is it okay if I give it 6V, or do I need to add a 5V voltage regulator for it?
Could you help me powering all the components? I don't really know how much current can the arduino give :-?

2. Should I use the L293D integrated motor driver or use the H bridge from the right? (I just have no idea what transistors to buy for it..)

3. Someone told me that I should use Eagle instead of Fritzing - for PCB layout.. does it worth the switch..?

Pages: [1] 2