sending data from a GPRS modem with (AT??) commands

Hi,
I have the same problem. It's been a while since you post your question, so maybe you already have an answer for that. I realy appreciate a lot if you give me some reply.
Help needed urgently.

Thanks.

Liliana

hi..
i am currently working on implementing some basic minimal network protocols for that purpose.

I think i would be more helpful if you could provide me more detail.

Hi,
Thanks for your reply.

My question is the same that you have posted: "How can i simply request web content with sending commands from serial port??"

I'm developing an API to connect to the GPRS network, so i write some initialize AT commandas, such as AT+CGDCONT=1,"IP","internet", directly to the modem. When i write ATD*99***1# (to dial the access number for GPRS) i receive CONNECT and then i see strange characters that i supose that's the PPP negotiation. My problem, for such a long time, is how to negotiate the PPP!  For now i'm using the rasdial.exe command for Windows, and the "pppd call" for Linux, to establish my connection to GPRS network, and then i use sockets communication to transmite and receive data. Well, it´s working but i realy want to do all that process diractly to the RS232 port (my modem).

Hope that this detail is enough.

Waiting for your response, best regards,
Liliana

hi Liliana ,
i have the same problem.did u get a solution??

regards,
Srinivas.

Hi njabin,

Thanks for your reply.

This is my problem: how to implemente the PPP protocol. I don't have the PPP protocol stack. I already known the theory of the implementation of PPP protocol, but i can't do it. I have tried to send some LCP packets (for the lcp negotiation - the begining) in response of some received but it didn't worked. Do you have some code on that, or the PPP packets for all the PPP protocol implementation?
Please give some reply on that, i'm searching for such solution for a long time.

Best regards,

Liliana

Hi liliGPRS ,
   Have you the ppp soucre code?
   It could be found in linux. Before you start the ppp, you should create the phsical data link.If you give me the email,I would send the ppp soucre code to you.
   BR/njabin

Hi njabin,

I would be perpetual grateful if you sent me the ppp source code. My email is est-l-amorim@ptinovacao.pt
Thanks for everything!

Liliana

Hi njabin...

Could You please send me a PPP source code?...
I'm facing the challenge to make my mcu & wismoquik "upgradable thru gprs connection" and I need an info "how to start"...

Hi guys,

I'm not sure you've got the answers you were looking for, but the following link have some info. for PPP connectivity. It is for microcontrollers but maybe helps.


http://www.microchip.com/1000/suppdoc/appnote/all/an724/index.htm
http://www.microchip.com/download/appnote/internet/00724c.pdf

Ric

Hi All,
          For an project we are using Siemens TC35 Module which is integrated with an device(built specifically for our project by our clients). The TC35 Module is connected with the device through the serial port.
            Now when i load the SIM Tray with the SIM card & switch on the device(integrated & interfaced internally with TC35), & send an command "AT", It gives the response "OK", But now I make an call to an the SIM card number from my personal mobile. My Mobile says that the "Number you are Trying is Switched OFF". Iam very much Confused wether the device is witched on or off. Can you help me what I have to do. Also when I tried with "COPN", "CGMR",  "CREG", "COPS"commands, I get the "ERROR" messages. So Kindly help me.

           Also if any one can send me an sample source code to GSM communication for Dialing up an ISP connection & connecting to an Server, It would be greatly helpful to me.

       Iam in very urgent position.

Waiting for your reply.

Regards,
Somasundaram.J
somu@softcrylic.com

You should enter the PIN first.

AT+CPIN = "XXXX" <CR>

Ric

Hi,
 I want to access GPRS network using AT commands. have an ericsson T68i phone connected to the RS232 port of my PC and I am sending AT commands from hyperterminal to the GPRS modem.
I have created the GPRS account on the cell phone using AT+CGDCONT = 3,"IP","proxy"
It returns OK.
Then when I send ATDT*99***3# command I see "CONNECT" on the hyperterminal and "connecting"on the cell phone for a long time. At the end the modem never connects to GPRS network at all. The problem is PPP stack has to be implemented, and LCP and NCP negotiation has to take place. I found RFC about PPP and some linux code about PPP but nothing is very clear how to implement that.
I want to implement basic minimum to establish the connection.
Thanks for you respose.

Hi,
     Really i need am imediate help from you experties in my problem please. am trying to send files from a gprs modem to another gprs modem where are both connected to PCs. i want to know all the possible ways to do that ? can i use AT commands to send files through GPRS if can how? i want to know this in a very short time please. other think how to recieve the file in the other modem and retrive it? please help me am stuck in my project and the professors waiting to give me the pelliant 0? please help??

mary

Hi Narash,

As you said, you need to have PPP ,CHAP, IPCP and TCP protocol implemented.
You can visit following link, where you can get an optimised TCP/IP stack along with its documentation,

http://www.embin.com/products/ETS100.asp?id=4

But for CHAP, you may need to implement MD5 (Message Digest Algorithm), which is not there in this stack. For that, you can refer to RFC1321, which provides you MD5 description along with the C code.

For best possible results, try to understand and decode the data packets you are receiving on the serial link.

SHRIDHAR