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Electronics => Electronics => Topic started by: Razor Concepts on November 27, 2009, 04:32:29 PM

Title: Cell-phone control with DTMF
Post by: Razor Concepts on November 27, 2009, 04:32:29 PM: Starting a little side project, cell-phone control board that decodes the DTMF signal into binary.
It was surprisingly easy to do and worked the first time. Right now the MP3 player (samsung p3 is so cool) is playing some DTMF tones. In the future there will be a cell phone instead.

RazorConcepts DTMF Decoder using MT8870 (http://www.youtube.com/watch?v=jxZb4zWXU58#)
Title: Re: Cell-phone control with DTMF
Post by: Razor Concepts on November 28, 2009, 09:03:32 PM: (http://i45.tinypic.com/dnetld.jpg)
Title: Re: Cell-phone control with DTMF
Post by: Spoil9 on November 29, 2009, 03:30:33 PM: Awesome build. But how do you plan to do remote answering and disconnecting of the cell phone? I'm assuming that you would plug this circuit into the ear piece jack on the cell phone?
Title: Re: Cell-phone control with DTMF
Post by: Razor Concepts on November 29, 2009, 03:45:23 PM: Most cell phones can be set to auto-answer which immediately picks up the incoming call, and will disconnect once the other guy disconnects.
Title: Re: Cell-phone control with DTMF
Post by: gaurav.p on November 30, 2009, 02:46:17 AM: how did u upload the eagle file like that .........pls tell

-gaurav
Title: Re: Cell-phone control with DTMF
Post by: Razor Concepts on November 30, 2009, 05:16:22 AM: I used print-screen and arranged it together in Microsoft Paint.
Title: Re: Cell-phone control with DTMF
Post by: TrickyNekro on November 30, 2009, 07:36:32 AM: Why to control a cell phone with DTMF where you can control it by a simple serial protocol...
I know that new phones have USB and not serial, but still I heard it's easy enough to do it..
you can create calls, sent SMS and so on??? I really think it would be more practical...

Still, every try is for good, and I wish you best of luck!!!
Hope I'm able to help you with anything that comes up!!!

Best Regards, Lefteris
Greece
Title: Re: Cell-phone control with DTMF
Post by: Razor Concepts on November 30, 2009, 05:29:00 PM: I was aiming this to be a simple thing, plug and play, so forth. So one could hook up a $10 prepaid phone or something and it works right off the bat, no setting up, etc. But that serial thing sounds interesting... but maybe only on more modern phones? I have a Chololate 2 and there is no standard USB connector or anything, either.
Title: Re: Cell-phone control with DTMF
Post by: Spoil9 on December 02, 2009, 09:16:26 PM: my recent couple phones have had the mini USB port for charging and data transfer but I have yet to find anything relating to how I can tap/ hack into that.
One thing I would like to do is add a second line to my service and keep that phone in my car connected to my security system so that when my alarm goes off I get a SMS txt. But that is way over my head at this point in the game. Maybe one day in the future.
Title: Re: Cell-phone control with DTMF
Post by: Razor Concepts on December 02, 2009, 09:27:17 PM: And hopefully a future without proprietary connectors!!

Anyways here is the breadboarded circuit, will have to make one minor revision to the schematic and off to BatchPCB it goes...

DTMF V2 RazorConcepts (http://www.youtube.com/watch?v=1AKvrurGaeA#)
Title: Re: Cell-phone control with DTMF
Post by: Razor Concepts on December 06, 2009, 12:38:15 AM: Final version. Placed an order for 2 pcbs from Batchpcb

(http://i45.tinypic.com/o8t7cl.jpg)
Title: Re: Cell-phone control with DTMF
Post by: Afroman on December 09, 2009, 12:16:22 AM: Where are you buying your DTMF decoder ICs from? They are pretty hard to find these days.
Title: Re: Cell-phone control with DTMF
Post by: Soeren on December 09, 2009, 05:06:39 AM: Hi,

Quote from: Afroman on December 09, 2009, 12:16:22 AM
Where are you buying your DTMF decoder ICs from? They are pretty hard to find these days.
Yes, sadly a lot of the "Oldies But Goodies" is vanishing, but you may be able to pick it up in a shop - go where the ham radio operators go, they use these chips a lot.

Or, accept the situation and start making the equivalent with a DSP chip.
A cheap way of DTMF decoding is using a dsPIC and the programming is nearly all done for you: Microchip Libraries for DTMF on dsPIC (http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=2680&dDocName=en536955)
Title: Re: Cell-phone control with DTMF
Post by: billhowl on December 09, 2009, 06:36:39 AM: Quote from: Afroman on December 09, 2009, 12:16:22 AM
Where are you buying your DTMF decoder ICs from? They are pretty hard to find these days.

Get it from ebay, lots of it.

http://shop.ebay.com/i.html?LH_AvailTo=180&_nkw=DTMF+decoder&_arm=1&_armm=63&_ruu=http://shop.ebay.com.sg/i.html%3F_nkw%3DDTMF%2Bdecoder%26_arr%3D1&_rdc=1 (http://shop.ebay.com/i.html?LH_AvailTo=180&_nkw=DTMF+decoder&_arm=1&_armm=63&_ruu=http://shop.ebay.com.sg/i.html%3F_nkw%3DDTMF%2Bdecoder%26_arr%3D1&_rdc=1)