gprs modem interface proceduer

[pisoiu]

gsm module benq

Techie, can you give me some info about M22 (price, supplier)? I am also interested in a cheap module at 1k units, with TCP/IP stack. I know that there are some previous comments about this issue, but they may be outdated.

/pisoiu

 

[techie]

simcom modems functional overview

M22 is about $50 in single quantity from China. I dont know about qty pricing. I think it should be arount $30-35.

 

[moo82]

cellon gsm module

i also had a question
is there a flash/ram memory on M22 (i think yes) ?so if yes can,wath 'is its volume and can i use it to stock some information or a programme?.
Thank you

 

[techie]

datasheet for gsm-sim300

I doubt it. I have not used the M22 yet. I have read it though. How much flash do you need. You can use a cheap EEPROM like 24C16 if you want to store some data.

 

[moo82]

software simcom server

30-35 is too cheap. but 40-45$ is the cheapest price you could have for 1K unites

Added after 8 minutes:

the fact is that i use an SDC before the GSM module and i want to diminuate the RAM and FLAsh memory.in fact I need 1Mo flash and 16Mo RAM

Added after 12 minutes:

SDC=SBC (sorry)

 

[techie]

datasheet modulo enfora gsm

That is quite a lot of memory for an embedded application. No I dont think M22 will provide you with this.

 

[techie]

gsm chipset 2009

Question:

In M22 GPRS, When you connect to a webserver by ATD*97#, you get a socket connection, right. Can you then simple send / receive packets over the socket connection. For example I want to download a webpage and I am connected to TCP port 80 of a web server. Can I send a GET ... command and receive the webpage in response.

 

[artem]

data sheets simcom300

I did not use the M22 for GPRS , i am planning to do so, but will try my best .

look at the atd command details :
D*<GPRS_SC>[*[<called_address>][*[<L2P>][*[<cid>]]]]

L2P possible values state that :

0 NULL
1 PPP
2 PAD
3 X25

That means you cant use direct get http command as
after the ATD is executed you should work with ppp protocol . So your ppp ip tcp protocols must be in place . You http protocol must be encapsulated into tcp/ip then into ppp then you can send these encoded data to the modem. Of course there will be connection establishment sequence on tcp level for remote socket .


I did not use the TCP builtin stack but at the page

279 of M22 AT commands document :

"2.8 M2M: Machine to Machine
The M2M AT command provides TCP/IP socket over GPRS connection.
These AT commands are only available in the M2M firmware."

that means you should use proprietary commands stated there to use internal builtin tcp stack of m22 . But document states that commands are applicable to M2M firmware . i do not know the version of software supporting M2m , it has to be asked from BenQ . If your modem firmware does support you can start with commands on mentioned page .


Good learning apprach - is to try to use modem directly from your PC by initiating internet dialup network - connect your modem to PC serial port and define new connection with dial number equal to *97# . At dialing you should be able to establish gprs connection and ppp network connection . BTW you can plug the serial link monitor to see what is going on on serial line . Or better try to capture data by etherial and decode them on ppp level . That will help you much to . So you can access the page using windows browser and compare that what is your software are doing with phone .

The issue with protocols is described here


Someone posted here code for PPP GPRS call .

i dont trust to this source , but you can give a try .

 

[techie]

using simcom300 module datasheet

The windows dialup networking works fine with M22. THe command is *99***1#. I can then download the web-page also. But THe problem is when I use the built-in TCP/IP stack. Then while I can connect with the server, I cannot get a response of my GET commands.

 

[clivechen]

sim300 avrfreak schematics

I give you the cheapest module: SIMCOM 100 or SIMCOM 300 they are only less than $20

 

[techie]

wavecom q2501 gsm modem

1. Have you used them for reliability.

2. Do they have GPRS and TCP/IP stack.

3. Any links to their website, distributors, sales etc

 

[moo82]

gsm module wavecom

Thank u clivenchen,
Could u please give me a supplier who could give me a quick quotation

thank u

 

[gorkin]

simcom 300 buy

SIM web site: http://www.simcommunication.com
Here You find more about sales agents.

Gorkin.

 

[techie]

simcom 300 transparent ip

The question remains. Has anyone used these for reliability.

 

[moo82]

buy g18 gsm/gprs module

Dear gorkin,
did they give you a quotation for the sim300 for 20$.In fact the Sim 100 they don't make it anymore
thank you

 

[moo82]

distibuter simcom300

Dear all,
Did somebody know if SIM300 is ROHS compliant???
Thank you

 

[tramp]

differrence between 900 gsm and 1800 gsm

Hi,
I am beginer for using module.I have a problem about sim100 modem.It get power on properly but not get register to network.what could be probable cause.Does it require to follow an initilisation sequence to follow?

Thanks in advance.
tramp

 

[techie]

gsm module distributor sim300d

The GPRS module have modem control pins like RTS CTS etc. I dont want to use them. Can I just leave these alone or loop them in a null modem style.

Any suggestions welcome.

 

[ashish.agarwal]

how to disable hardware flow control in sim300

I have used Wavecom and SIMCOM modem. There is some problem of delay messaging in SIMCOM.

--Ashish

 

[pisoiu]

gsm modules cheap

The GPRS module have modem control pins like RTS CTS etc. I dont want to use them. Can I just leave these alone or loop them in a null modem style.

Any suggestions welcome.

These pins are used only if you choose to do so, using hardware flow control. Take a look at AT commands concerning hardware flow control (AT&K, AT+IFC), set all to disable, and all you have to do is to play with RX and TX, leaving everything else. However, if you do GPRS communication, I highly reccomend you to use flow control (either hardware RTS/CTS or software XON/XOFF). Depending on the network conditions, if you send large ammounts of data, the modem may not be able to keep up with your mcu, and without flow control, you may loose data.

/pisoiu