simcom sim900

Go To Last Post
10 posts / 0 new
Author
Message
#1
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Hi,

i'm working with ATmega 32u4 ,and connect to it the sim 900 modul,

i'm trying to send or recieve phone call using AT command , but i think that the modul

not connecting to the cellolar network,

how can i be sure what the problem is ?

 

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

I guess you could start by examining some of the other sim900 related threads on this website. Use the search facility in the top right hand corner.

 

Confirm that you are using the correct AT commands and that you are checking the sim900's responses after each command.

 

Cheers,

 

Ross

 

Ross McKenzie ValuSoft Melbourne Australia

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

i'm using in the SIM900-AtCommands.PDF to the AT command,

part of the problem that i dont know how to get the respons from the sim 900,

do you have a simple program that i can us?

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Well since you don't appear willing to use google or any search engine yourself...

 

http://www.seeedstudio.com/wiki/...

 

or this more complete hand holder...

 

http://linksprite.com/wiki/index...

 

and there is also this one

 

http://tronixstuff.com/2014/01/0...

 

"Beggars cannot be choosers"

Ross McKenzie ValuSoft Melbourne Australia

Last Edited: Sun. Mar 15, 2015 - 01:11 PM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

I'd tryed this codes but ' i'm  getting  noting back from the modul,

i'm writing AT command and getting any answer.

 

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Well my mind reading crystal ball is faulty at the moment, so unless you can provide any evidence of what you have actually done... I am afraid no one will help you further.

 

Ross McKenzie ValuSoft Melbourne Australia

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

http://tronixstuff.com/2014/01/0...

*Last link in post #4*

 

If you have a USB to TTL converter, and a terminal program you could send the commands manually and see what comes back.  THen once you have determined that the SIM900 is functional then add your AVR.

 

JIm

I would rather attempt something great and fail, than attempt nothing and succeed - Fortune Cookie

 

"The critical shortage here is not stuff, but time." - Johan Ekdahl

 

"Step N is required before you can do step N+1!" - ka7ehk

 

"If you want a career with a known path - become an undertaker. Dead people don't sue!" - Kartman

"Why is there a "Highway to Hell" and only a "Stairway to Heaven"? A prediction of the expected traffic load?"  - Lee "theusch"

 

Speak sweetly. It makes your words easier to digest when at a later date you have to eat them ;-)  - Source Unknown

Please Read: Code-of-Conduct

Atmel Studio6.2/AS7, DipTrace, Quartus, MPLAB, RSLogix user

Last Edited: Sun. Mar 15, 2015 - 11:00 PM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 1

The first thing you want to do is park the AVR. Just wire a SIM900 up to a PC and use a terminal to type ATxxxx commands at it. Explore what the commands do and just see if you can dial (ATD) or answer (perhaps ATS0=1 perhaps?). Only when you are completely familiar with the sequences required to achieve various functions can you think about then moving what you have been typing manually to be issued by the AVR. Of course when you do it manually and get responses like "OK" or "CONNECT 2400" or whatever you can instantly recognize hat's going on. The "clever bit" of doing this with a micro is to have it able to detect and handle every possible response it may give for every AT command you may send it.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

clawson has nailed it:

First, make sure you can do it manually on a terminal. Spend time getting a good understanding of the module's AT Command set, and the procedures to do various tasks.

 

Only then should you move on to trying to implement that on a microcontroller.

 

Quote:
The "clever bit" of doing this with a micro is to have it able to detect and handle every possible response it may give for every AT command you may send it.

Absolutely!

 

Do not copy the all-too-frequent error of just sending commands, ignoring responses, and relying on delays.

 

That's like driving a car with your eyes shut, and just hoping that you turn the wheel at the correct time - and that there's no other cars in the way!!

 

https://www.avrfreaks.net/comment...

 

Top Tips:

  1. How to properly post source code - see: https://www.avrfreaks.net/comment... - also how to properly include images/pictures
  2. "Garbage" characters on a serial terminal are (almost?) invariably due to wrong baud rate - see: https://learn.sparkfun.com/tutorials/serial-communication
  3. Wrong baud rate is usually due to not running at the speed you thought; check by blinking a LED to see if you get the speed you expected
  4. Difference between a crystal, and a crystal oscillatorhttps://www.avrfreaks.net/comment...
  5. When your question is resolved, mark the solution: https://www.avrfreaks.net/comment...
  6. Beginner's "Getting Started" tips: https://www.avrfreaks.net/comment...
Last Edited: Mon. Mar 16, 2015 - 10:35 AM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

There's a whole bunch of documents for the SIM900 on the SIMCom website:

 

http://wm.sim.com/producten.aspx...

Top Tips:

  1. How to properly post source code - see: https://www.avrfreaks.net/comment... - also how to properly include images/pictures
  2. "Garbage" characters on a serial terminal are (almost?) invariably due to wrong baud rate - see: https://learn.sparkfun.com/tutorials/serial-communication
  3. Wrong baud rate is usually due to not running at the speed you thought; check by blinking a LED to see if you get the speed you expected
  4. Difference between a crystal, and a crystal oscillatorhttps://www.avrfreaks.net/comment...
  5. When your question is resolved, mark the solution: https://www.avrfreaks.net/comment...
  6. Beginner's "Getting Started" tips: https://www.avrfreaks.net/comment...