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How to use GSM/GPRS module

Former Member

Hi,

 

I am a student and I am working on a data acquisition board that would implement a GPRS?GSM module. I will use it to send messages to a mobile phone.

Can anyone suggest me a schematic or at least a good supported module.

I've been searching, but none of the devices found have a good documentation.

I would like to use an ATMEGA uController.

 

I have found a nice schematic but I do not understand it entirely.

 

Thanks for the help

Attachments:
imageAVR-GSM.pdf
  • 0

    LS Research may help you.

    http://www.lsr.com/products/radio_modules/

     

    Also,

    Call the guys at NextGen RF in Weaseca MN, USA.  they can help too.

    http://www.nextgenrf.com/

     

    Good Luck ,

    bernard...

  • 0

    Hi, I saw your other post about this.

     

    The SIM300 is easy to use with the AVR devices. Pay careful attention to the datasheets for the SIM300 modules though as I see on the schematic for the link you posted that they connect +5V to the GSM module. This is likely to destroy it as the max voltage is 4.5V. Ideally you want to use 4.0V and this is what I use with the SIM300 modules and they work very well. They are remarkably cheap too.

     

    Be careful also on the TXD and any input lines etc as these are not rated for anything above 3.0V so use a resistor inline to limit the current with your micro running on 3.3V and you should eb OK. This has been working for me for a number of months wtih no issues.

     

    Driving them is easy and they have a very nice TCP/IP implementation so you can even use GPRS with the AVR with no need for a TCP stack on the AVR. Just use AT commands to setup the PPP dialup over GPRS and then the TCP connection to whatever you want to connect to.

     

    If simply want to send and receive SMS, then that is just as simple to do via the AT commands.

     

    Good luck with your project. If you get it all working you will learn valuable leasons on how to get a GSM module to work with microcontrollers. There is lots of potential for remote applications once you do.

     

    Regards,

    Dave...

  • 0 in reply to DaveMcLaughlin

    Hi Dave,

     

    I am pleased to finally find someone who has used the device on some projects.

    Now I will surely use the SIM300. Can you suggest me some places where I can buy it at a lower price?

     

    Thank you for your answer

  • 0 in reply to Former Member

    Hi Andexandru,

     

    Which country are you located in?

     

    I am located in Indonesia and use a supplier from Singapore. (I am an expat from Scotland living and working here)

     

    Simcom have a very large worldwide network of distributors who you should be able to purchase from, hopefully there is one local to you saving you from purchasing overseas.

     

     

    Dave...

  • 0 in reply to DaveMcLaughlin

    Hi Dave,

     

    I am from Romania. I have found some SImCOM distributors nearby but I am not really sure if the price is cheap or expensive. A sim300C is aproximately 25EUR net price.

    By the way is there a major difference between SIM300C or SIM300 or SIM300D? Which component is more easy to implement.

    I would also like to use a DIP socket because the soldering will be done manually.

     

    Thanks 

  • 0 in reply to Former Member

    Check with the distributor as I was told that some SIM300 models are on end of line.

     

    If you want a DIP type, the nearest you will get is the SIM300C or SIM340C (Quad band) which have 1.27mm pitch connectors. The SIM300D is not recommended for hand soldering as the antenna connections are under the unit and require reflow soldering. It is much smaller than the other modules.

     

    I have managed to solder the 0.5mm pitch connector for the SIM300 and SIM340. You just need a good soldering iron and some solder wick to clean them up.

     

    Your prices sound about right for the region. Is this from a Romanian distributor?

     

    Dave...

  • 0 in reply to DaveMcLaughlin

    Hi,

     

    Yes this supplier is from Romania. There are few that sell wireless modules here, or did not manage to find them till now.

    You did not answer my question...

    When I was asking if there is a major diffrence between the sim modules I was refering to the configuration part. I mean do I need some extra drivers or some control unit configuration... I don't know... Are them all the same concerning this aspect?

     

    Alex

  • 0
    i have a good ebook about GSM and the microcontroller ,but it's in french
  • 0 in reply to Former Member

    Hi Alexandru,

     

    They all seem to be very similar hardware wise but please check the datasheet for the one you want to use and make sure you follow the guidelines.

     

    For control, you need the following as a minimum:

     

    Power ON control (use the circuit they provide in the HW manual. Do not connect an IO pin direct the module as the input has to be open collector)

     

    LED status out. Design this in as it allows you to see what the module is doing. The LED is great for feedback as it pulses during data connections and during network registration.

     

    Use RTS and CTS if you can but I have it working without. Depends on your processor speed. I have TCP/IP working at 57600 bps without any issues.

     

    Watch your IO pins from the processor to the modem to make sure the limits are not exceeded. If you processor is running at 5V DO NOT connect direct to the GSM module. The Analog Devices ADMU bus isolators are ideal for this. I use them with a Telit modem and it works perfectly. You can power the ADMU from the VDD output from the modem as this will be at the same voltage as the IO pins.

     

    Good luck.

    Dave...

    PS.. When you do your software, write code to read the registration onto the network and read the signal strength. If the module is not registered, sending SMS or trying to connect over GPRS will not work. It takes a few seconds from power on before the module is registered on the network.

  • 0 in reply to Former Member

    Hi Maqil,

     

    Can you give me a link or can you attach it ?