Out of PINS with SIM900 GPRS shield

Hello everyone,

I'm new with arduino, and I have bought a GPRS shield SIM900 from elecfreaks.

My problem is that the GPRS shield uses all arduino pins, and it doesn't have extra pins. I want to add a few sensors to the arduino but I don't know where.

Thank you in advance!

have the same one, though i have Mega so plenty of pins there, are you using nokia lcd? that socket can be used, though 3 pins you have to count out, there is gnd, aref and 3,3v on it.so you can use those, depending of what type of sensors, and how many you have them, you may want to use shift registers. (Btw, I was hoping that you can verify my issue I'm having in this thread: http://forum.arduino.cc/index.php?topic=167284.0 but ou can use just example SMS_RECEIVE from GSM library)

Thank you for answering.

┬┐And those pins are digital? Is there a way to connect only the TX RX pins, so I have the rest of the pins free?

One more question, when I press the power on button, the net led blinks for a while (3 seconds) and then it turns off and nothing, what can it be?

thank you in advance

on my mega those are pins 9-13 PWM Digital (do not now what arduino you have),no way to have only TX/RX, there is also control pin for auto on/off if i remember correctly,

and one very important thing, you have to have another power source for this shield,

outmost swich is reset, middle switch is power for the board (press it for about 2 seconds to power it on), last switch is shield reset.

he3r0: on my mega those are pins 9-13 PWM Digital (do not now what arduino you have),no way to have only TX/RX, there is also control pin for auto on/off if i remember correctly,

and one very important thing, you have to have another power source for this shield,

outmost swich is reset, middle switch is power for the board (press it for about 2 seconds to power it on), last switch is shield reset.

thank you, I've realize about the power supply :)

he3r0: on my mega those are pins 9-13 PWM Digital (do not now what arduino you have),no way to have only TX/RX, there is also control pin for auto on/off if i remember correctly,

and one very important thing, you have to have another power source for this shield,

outmost swich is reset, middle switch is power for the board (press it for about 2 seconds to power it on), last switch is shield reset.

Do you know how can I attach an analog sensor (ie: a temperature LM35 sensor)?

i've used DHT11 for both, temperature and humidity, http://muziol.com/dht11-and-bluetooth/

basically for LM35: outside pins 5V and gnd, middle pin on LM35 gives you temp.

http://pscmpf.blogspot.com/2008/12/arduino-lm35-sensor.html

he3r0: i've used DHT11 for both, temperature and humidity, http://muziol.com/dht11-and-bluetooth/

basically for LM35: outside pins 5V and gnd, middle pin on LM35 gives you temp.

http://pscmpf.blogspot.com/2008/12/arduino-lm35-sensor.html

I mean, attach this to the SIM900

thank you

in my case it could be 5v and gnd on outside pins of LM35, middle pin of LM35 would go to any of the free pins, 14 to 51 (52 i have already taken)

juanmas07: Hello everyone,

I'm new with arduino, and I have bought a GPRS shield SIM900 from elecfreaks.

My problem is that the GPRS shield uses all arduino pins, and it doesn't have extra pins. I want to add a few sensors to the arduino but I don't know where.

Thank you in advance!

Hi, sorry I just see your post now, and I hope it's too late and you already have got your answers, but just in case.... did you read the doc. for this shield ? It actually uses only a few I/O from arduino, most of them are still available :

Pins usage on Arduino

D0 - Unused if you select software serial port to communicate with GPRS Shield D1 - Unused if you select software serial port to communicate with GPRS Shield D2 - Unused D3 - Unused D4 - Unused D5 - Unused D6 - Unused D7 - Used if you select software serial port to communicate with GPRS Shield D8 - Used if you select software serial port to communicate with GPRS Shield D9 - Used for software control the power up or down of the SIM900 D10 - Unused D11 - Unused D12 - Unused D13 - Unused D14(A0) - Unused D15(A1) - Unused D16(A2) - Unused D17(A3) - Unused D18(A4) - Unused D19(A5) - Unused Note: A4 and A5 are connected to the I2C pins on the SIM900. The SIM900 however cannot be accessed via the I2C .

Hope this helps, (better if it doesn't, in fact, meaning you don't need help anymore ;) ) jf