Re: How to control SIEMENS C35 using microcontroller 8051

From: CBFalconer (cbfalconer_at_yahoo.com)
Date: 01/09/04 

Date: Fri, 09 Jan 2004 16:47:54 GMT

Lawrence wrote:
> "Mark A. Odell" <nospam@embeddedfw.com> wrote in message
> > llllgh@yahoo.com (Lawrence) wrote in
> >
> > > Hi, i'm doing a final year project with tittle remote process
> > > control control using a mobile phone. but i cant communicate
> > > the microcontroller 8051 with SIEMENC C35 using a data cable.
> > > How to using the AT Command? It's only for C language or can
> > > use in microcontroller assemble language?
> >
> > AT commands are from the old Hayes Modem company. The command
> > set is simple ASCII. Once you get the baud rate and physical
> > layer drivers correct for the C35 phone you will be able to
> > send it AT commands in C, Forth, Pascal, BASIC, or assembler.
>
> how do i to initial the modem in the data cable? does it require
> any delay when sending data?

An "AT" controlled modem is basically in one of two states: active
or quiescent. In the quiescent state it receives commands that
start with at and end with <cr>. The AT portion serves to set the
communication speed, and the modem adapts accordingly.

It usually gets out of the quiescent state to the active state via
the ATA or ATD commands. In the active state it first
synchronizes with the remote modem, and then becomes transparent
to data. ATA causes it to answer an incoming call, and
ATD<number> causes it to dial and originate a call.

In the process of switching states (or processing commands) it
normally sends back responses, such as OK, or possibly just a
number.

So you don't really have to time most things. Their is more than
this, of course, such as response to DTR line, and use of CD line,
etc. IIRC the modem will usually give help when sent AT?<cr>.
Simple, portable, and effective. That is why Hayes was king of
the modem market for a long time and the protocol became virtually
universal. 

-- 
Chuck F (cbfalconer@yahoo.com) (cbfalconer@worldnet.att.net)
   Available for consulting/temporary embedded and systems.
   <http://cbfalconer.home.att.net>  USE worldnet address!

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