T230 direct interfacing with microcontroller

hello freinds
i am trying to interface a microcontroller with T230 mobile.i am trying to connect directly the controller with mobile as they are TTL compatible.
i dropped the voltage by 3.3V by using zener diode.
the problem is T230 has auto baud rate detect.how to configure it.
can anyone help

its simple.. just set your controller to whatever baud you want. and at the startup of your circuit. send 'U' capital U, because the ascii code of U is 55H
so.. that becomes 01010101
that will send a square wave which help T230 to detect and configure the baud automatically.
you can send some 10 characters. of 'U' (capital U)

thanks my freind

you're welcome

hi ajay
thanx a lot for ur immediate reply.do u have any circuit diagram for this sort of interfacing(ie controller and a mobile)just to make sure!
and one more doubt
AT command for sending sms is AT+CMGF,after u give ur phone numberwe have to wait for > this symbol ,how to do this in the code.Can we wait for few seconds
and then send the message or we have to wait to get '>' equivalent hex code to
appear in SBUF and then send the message.

2. I actually started the communicaton without sending the U's as u told
will this affect the communication between controller and mobile

regarding your doubt:
1. waiting for '>'
how you want to do this? i mean in assembly or c?
in assembly... you can do something like this..
[hide]here: jnb ti,here
clr ti
mov a,sbuf
cjne a,#'>',here[/code]
So above will do something like.. it will check for > if not equal then it will again go back and wait for that character, you can put this in a routine like "check_prompt"
so after sending the AT command
"AT+CMGF"
you can call the routine "acall check_prompt"

2. well... i am not sure how the phone will behave without sending 'U'
actually U is a synchronizing character in most of the communications Like FBUS etc.

I don't have any circuit for interfacing T230. moreover, i never used that phone before. you can simply check the phone pinouts and voltage levels for interfacing considerations.
if anymore problems, please post...

hi
i am using C language.the character '>' appears after some time after the command AT+CMGF is given so can i put a delay in the program after sending
the command and then send the sms text.will this work?

Actually i tried to do the FBUS communication .it didnt even work with my PC(using nokia2100& max232 interface).i am sending a circuit diagram which i got
from the net.i used this interface for checking AT commands.

FBUS protocol is little difficult and tricky and you need good amount of coding i think i haven't tried, but i analyzed the protocol very closely. That is not the point right now.

Ok taking your project.... you need not to put delay.. actually.. just do this way.. keep waiting for the character.. that will automatically put the delay. use polling method no need to use interrupts... as in case of AT commands, lock step method is preferable.

C code..

back:
      while(!TI);
             TI = 0;
     if(SBUF!='>
')
             goto back;
//if received char is not '>
' then go back and wait.. 
//if the received char is '>
' execute the next code..  

hi ajay
i have a doubt and i would like to know whether it is better to use a serial and max232 interfacing of a controller and mobile or a direct interfacing is better.
have u tried to interface them friend
thank you

no i have not used T230. The thing is.. by using Max232 you can have a longer connection cable. The normal TTL signals cannot go to longer distances via wires. So thats the reason we had introduces these new types of communication techniques.

Just giving you an example, someone might have thought that the range for RS232 is less so they invented new RS485 just to communicate over longer distances and better features.