Gprs/gsm

Hey Guys,

Im intersted in getting a picaxe to retrieve information from a website, i.e a http post or get.

is this possible simply with a GPRS/GSM module ?

have tried googling with limited success.

Regards
Lachlan
 

Fletch

Member
Hey Guys,

Im intersted in getting a picaxe to retrieve information from a website, i.e a http post or get.

is this possible simply with a GPRS/GSM module ?

have tried googling with limited success.

Regards
Lachlan
Depending on the module it should work very much like a serial modem (ie uses the Hayes standard AT command set.) You use a special command sequance to connect to GPRS followed by the usual handshaking nescessary to set up a PPP connection, once that is done you have an IP address and a connection to the internet.


I have a number of Motorola G18 modules that I got cheaply on Ebay that I have plans to use with a microcontroller one day. The Motorola notes for these devices may be useful.
 

hippy

Technical Support
Staff member
It might be possible if you have the right GPRS/GSM module but there's a lot more to it than just connecting to a base station and getting a web page. You'll need a whole stack of software to drive the module which is probably beyond the abilities of a PICAXE.
 

krypton_john

Senior Member
Hey Guys,

Im intersted in getting a picaxe to retrieve information from a website, i.e a http post or get.

is this possible simply with a GPRS/GSM module ?

have tried googling with limited success.

Regards
Lachlan
Basically no. To do the post or get would require a TCP/IP connection but GPRS/GSM only gives you a serial connection.

However you could run a simple server appilcation on a computer that answers a dial modem, recieves messages and then does the post of get using it's internet connection. Then your PIXAXE/GSM module could dial into that server.

This device:
http://www.sparkfun.com/commerce/product_info.php?products_id=279
has a python interpreter and memory onboard so it could be programmed up to do the messaging on behalf of the PICAXE.
 

Fletch

Member
Basically no. To do the post or get would require a TCP/IP connection but GPRS/GSM only gives you a serial connection.

However you could run a simple server appilcation on a computer that answers a dial modem, recieves messages and then does the post of get using it's internet connection. Then your PIXAXE/GSM module could dial into that server.

This device:
http://www.sparkfun.com/commerce/product_info.php?products_id=279
has a python interpreter and memory onboard so it could be programmed up to do the messaging on behalf of the PICAXE.
GPRS is a packet protocol all you need to do to get an IP address from the network is to request one via PPP in exactly the same way that you would request one from a dial up ISP. In fact with some adaptations of dialing strings you can connect via GPRS using a DUN style of application.

Using the GSM module as a cellular modem is called CSD (Circuit Switched Data) mode and not all rate plans support it. Tmobile provides it as a backup when they configure GPRS, AT&T generally dont.
 

krypton_john

Senior Member
GPRS is a packet protocol all you need to do to get an IP address from the network is to request one via PPP in exactly the same way that you would request one from a dial up ISP. In fact with some adaptations of dialing strings you can connect via GPRS using a DUN style of application.

Using the GSM module as a cellular modem is called CSD (Circuit Switched Data) mode and not all rate plans support it. Tmobile provides it as a backup when they configure GPRS, AT&T generally dont.
But you need a ppp stack. Where is that going to reside?
 

andrew_qld

Senior Member
But you need a ppp stack. Where is that going to reside?
Thats right, once you connect to the internet you still need the IP address, DNS etc etc which is all in the TCPIP stack,

I think it would be possible to connect up to a PC using dial up serial protocall (slip) and feed it simple command line stuff to download a very small file (that it had downloaded from the internet?) and feed it to a picaxe via serial. The data wouldn't want to be very big though.

The alternative is a picaxe net server. Or a SimpleLan (or simmilar) TCPIP module that talks to the pcaxe using serial. But then you have to be able to get the "blue cable" into the phone module some how. A bluetooth to ethernet bridge perhaps?

Either way its not a simple project.

Andrew
 

Fletch

Member
There are microcontrollers that can do this kind of thing and have enough space to hold the stack it's just a little bit beyond a PICAXE. On the other hand I doubt those microcontrollers cost just a few pounds and are as easy to develop code for. Like a lot of things it's a horses for courses question.
 
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MPep

Senior Member
This maybe a bit late but the Lantronix XPort might be useful here. I have only read about them though.
 
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