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I have arduino uno and this SIM900 gprs/sim. I followed this tutorial and everything was fine. The code was properly updated and led lamps was properly shining, but it won't send sms or call someone. Then I trid code from this site, but my serial monitor won't recognize messages t or d. Nothing happens. What do I do? Thanks.

Ron Smith
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Đuro Pedala
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  • can you switch on /switch off your module from arduino? – dmSherazi Feb 10 '15 at 13:57
  • First off all thank you for answering, if you think on reset button from arduino nothing happens on gsm modul when i push it. – Đuro Pedala Feb 10 '15 at 16:20
  • I mean if the modem is on , can you make it off using AT+POWD ?? Just to be sure you can send correctly to modem – dmSherazi Feb 10 '15 at 17:30
  • I just try, and no i can't... I try powering leds with digital pins through modem and also does not work. I dont no,and all is well soldered... What do you think, what should i do? – Đuro Pedala Feb 11 '15 at 12:57
  • please check the updated ansswer – dmSherazi Feb 11 '15 at 13:12
  • No i can't, sry if i dont understand something i am just beginning learning. – Đuro Pedala Feb 11 '15 at 13:26
  • go through this http://www.elecfreaks.com/wiki/index.php?title=EFCom_GPRS/GSM_Shield – dmSherazi Feb 11 '15 at 13:28
  • turning on/off module from arduino – Đuro Pedala Feb 11 '15 at 13:28
  • connect you shield to pc and switch it on manually! see what you get on the serial console – dmSherazi Feb 11 '15 at 13:29
  • the shield has a `selectable serial port` did you checked if you are using the correct one ? – dmSherazi Feb 11 '15 at 13:32
  • problem is i dont get nothing to serial monitore, and yes i try to use other ports. My modem is little diferent then this one http://www.geeetech.com/wiki/index.php/Arduino_GPRS_Shield. i am waiting to seler send me exactly datasheet. this is modem what i got http://www.ebay.co.uk/itm/SIM900-GPRS-GSM-Shield-Development-Board-Module-For-Arduino-High-Quality-/271621338401?ssPageName=ADME:X:RTQ:GB:1123 – Đuro Pedala Feb 11 '15 at 14:42

1 Answers1

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I would suggest you to use this library as it works and is tested.

It’s a library developed for Arduino’s shields that support SIM900/SIM908.

You can find many shields on market supporting SIM900 and SIM908 modules. Most of them work in same way. You will be able to manage, using your SIM card: call, SMS, GPRS, HTTP, e-mail, UDP, POST-method, GET-method, GPS and other features.

UPDATE 1

First you have to debug your serial communication. Its Important to check if your commands are sent correctly from the controller .

I would suggest connecting your shield to your PC and send commands to it. This way you would know what replies you get from the module and you can debug it easily.

If you still get problems let us know and don't forget to share your serial logs

dmSherazi
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