Phone Control with Microcontroller (just dial & talk)

[Wings]

I have an application to marry a cellphone with an emergency callbox. I need to dial the number via the microcontroller, than allow a user to talk via the cellphone's external audio in/out connections (NOT thru the phone's mic & speaker). Questions I have are: What is the data format to use for dialing, is it the AT command set used in GSM phones?? (I would like to be able to use TDMA and CDMA phones, not only GSM) How do you instruct the phone to use the external audio in/outs and not its internal mic & speaker? Do most data cables bring out the external audio in/out pins to the DB-9 connector end? Where do I find a pinout for the cables I would need? (Help me Obi-Wan Kenobi, you're my only hope.)

[Marko_FN]

Hi,

You could do device like this if the phone supports such cable connection and your microcontroller is able to give commands correctly to the phone. The capability to use the external audio and give AT-commands can vary between different phone models and at the moment there is no pin interface specifications available by Nokia.

In most cases if you dial out a voice call and have headset connected the call should automaticly be available via headset.

Best regards,

Marko Tuukkanen
Forum Nokia

[williamwklee]

> What is the data format to use for dialing, is it the AT command set used in GSM phones?

(Most of the) Nokia mobile phones are actually using a software modem interface to interact with a PC (running Windows). You can set up such RS-232 to phone connection and use a com port monitor to see what signal did the PC sent to the phone for making outbound calls.


> How do you instruct the phone to use the external audio in/outs and not its internal mic & speaker?

This is simple, just connect your external mic to pin 3 and external speaker to pin 5 (if you use Nokia 51xx, 61xx, 62xx, 71xx etc). You can refer to some of the information on the Internet like:

http://www.atrox.at/datacable/connector/
http://www.nobbi.com/steck_nok.htm

These are not offical information, use at your own risk.


> Do most data cables bring out the external audio in/out pins to the DB-9 connector end?

No, usually not. Because this will let the phone "thinks" it is connected to a handfree kit rather than a data cable.


> Where do I find a pinout for the cables I would need?
Already answered.

Actually, you need to combine a handfree kit (of course, to convert the mouth piece and ear piece to your perfered device) and a data cable. A lot of (non-offical) information is on the Internet. Start your favor search engine and search for the stuff you want.

Hope this helps,

William WK Lee
Hong Kong.

[andy.student]

Hello

please help im doing a similar project where i use a pic 16f84 microcontroller to dial a number. im using at commands but im not sure if im using them properly. from the pic im sending ATD<then a number> are these in ascii?

please help any information on the FBUS, voltages that the characters should be at (TTL or RS232) ive set the pic up to send out information in rs232

Thanks

Andy

[egoycool]

Hi Andy,I'm from Chile, I'm in a similar proyect an here is a page where you can find some info:

http://www.nobbi.com/steck_nok.htm

How did you send the at commands trough the pic?
Why didn't you use the pic 16c6xx wich has a serial port?
Any information please send to egoycool@puc.cl, thanks!

[mamede]

SAME PROBLEM. (from brazil)

i´m trying to find out the format to dial a number using serial comunication.

No success.

[sureshee]

hi ia also doing similar project in CELLPHONE,canu plaese sa me where to take output from CELLPHONE,i know that we should connect it in SERIAL INTERFACE IN CELLPHONE,where to connect it because the serial port has 5 pins namely Tx,Rx,GND,VPP and one more...please say me thanku
mail me if u hav any details at : sureshee@gmai.com

[sureshee]

whether the CELLPHONE ACCEPTS TTL LOGIC OR RS232 form of input please say me at sureshee@gmail.com