Interfacing of GSM modem with 8051 microcontroller

" if you r connecting a modem with your 89s51 then u require is direct wire interface no max232 conversion"
No!!
This is completely false!

If you are using a (GSM) modem then it will use a true RS232 interface and will require an RS232 transceiver (MAX232, etc)

If, however, you are using some sort of embedded GSM module, then it may just use logic-level signals.
But you must check the datasheet to confirm this - some modules use non-standard logic voltage levels...!

but with a sense,
i have tried several modems the person is failing to get results just bcoz he is terribly confused with null modem usart architecture. moreover i can bid that more than 70% modems are ttl compactible with 8051..
like wavecomm
ok with you understandings i just want to help him out not you.
best way to get knowledge is to teach somebody nor to discourage like that you have done..

first you write i think there is a prob with your rs232 -to TTl gateway , if you r connecting a modem with your 89s51 then u require is direct wire interface nomax232 conversion takes place...bcoz with PC it does..

Of course the fact that you use Stupid Monkey S*** should automatically make anyone dismiss what you write, but when you state something as an "universal truth" you may mislead someone.

then when corrected, you continue, still using Stupid Monkey S***, i can bid that more than 70% modems are ttl compactible with 8051.. so what do you actually mean besides "I have no idea whatsoever what I am babbeling about"

Most (I know of no other, but as opposed to you I do not do generalizations when I do not know) modems are made for PC use and thus will have standard RS-232 interface

Erik

Note
This message was edited because of rude or abusive language.

hell!
too much talk now!
i illustrated the thing with my mind,if there is a prob
u r nobdy to talk rubbish like this , i think u r sick
i never think of a guy like you. i think the administrator is sleepy here! bad bad very bad manners

u r nobdy to talk rubbish like this , i think u r sick

Now, WHO is "talking rubbish" what else is 'u' 'r' etc English it is not

Erik

"null modem usart architecture"

Null-Modems and U(S)ARTs are completely differnt issues.

"moreover i can bid that more than 70% modems are ttl compactible"
No. Again that is not correct

Again, you need to distinguish a true Modem from an embedded module:
A Modem will use RS232 levels and, therefore will require and RS232 Transceiver;
An embedded Module most probably will not use RS232 levels - and it may not even use standard logic levels.

Consider Wavecom, for example:
Their Fastrack is a Modem and it most certainly does use RS232 levels;
Their Integra is an embedded Module and it does not use RS232 levels

Remember also that an RS232 transceiver inverts the signal...

"i just want to help him out"

Giving him stuff that is blatantly wrong does not help him!
In fact, connecting RS232 levels direct to an 8051's pins could well damage them!

Please can u send me the code what you have solved for the interface for 8051 with gsm modem because i am facing same problem what you has posted . please send tha code. this is for my college project purpose

"please send tha code. this is for my college project"

Surely the whole point of a college project is to demonstrate that you can solve the problem yourself?

After reading this thread, you should have sufficient information & resources to enable you to complete your project.

If you have specific questions, then ask them - but don't just cheat your course by copying someone else's work!

"gsm inter facing with 8051 microcontroller"

Yes, apart from the spurious space in "inter facing (sic)", that is the subject of this thread.

Was there a question you wished to ask, or a contribution you wished to make?

Wow,

It sounds like we might actually have someone here who actually KNOWS something.

One thinks, I might add, is that can we try to keep this down to a dull roar?

We should not be trying to attack each other, but HELP each other !

Yes, we are all at different steps on this learning curve, but should remember to think of when we were at the bottom, and looking up and hoping someone would give us a hand.

All the best from John, Newport, RI, USA

Hi,

I am sending ATD command to GSM module.
It gave me "NO CARRIER" and after this, when i tried it is giving "NO DIAL TONE"

what is meaning of this?
but my hardware is working fine because i am able to read hardware details of GSM module and also i can read SIM ID number...

so, if i want to try ATD command, how can i proceed?

Thanks,
Sandy

"I am sending ATD command to GSM module.
It gave me 'NO CARRIER'"

That means that it did not successfully connect to the called party.

Did you dial the correct number?
Did the called party answer?
Is that number data-enabled? (some operators require a separate number for data calls; some do not permit data calls on some tarrifs - particularly pre-pay)

"after this, when i tried it is giving 'NO DIAL TONE'"

Presumably, this means that you have no service - check the modem manual for more specific details.

Also check the modem manual to see if it can give any extended and/or more informative error information.

"my hardware is working fine because i am able to read hardware details of GSM module and also i can read SIM ID number"

That shows that you are communicating with the module; it does not show that you have GSM service, nor that the calls you are attempting are permitted for the SIM that you are using on the Network that you are using...

I agree with you Andy. How dare you to ask for the code?? Get up and do some work.

Andy was right. People/students or anyone who try to get a "degree" should not cheat. By the way, I was confused too when someone could write a sentence but made no sense.