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dtmf project [help]

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Ajay

Thu Jan 31 2008, 10:48AM

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sorry rahul.. i missed your thread, its not DPOT relay.. its DPDT (dual pole double throw) Relay. Its a type of relay. yes you need to take speaker off by cutting wire.

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rahuljin

rahuljin

Sat Feb 02 2008, 01:03AM

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thanks for the reply !!!

i dont get the use of this DPDT reply !!!

so what is the need of ring detector, i mean nokia has a option to accept the call automatically !!

also i want to ask that the wires are attached to relay or can i attach them to dtmf decoder ???

Ajay

Sat Feb 02 2008, 01:28AM

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as perl the link you posted in your first post, that person uses telephone line not a mobile phone. so you can remove relay and directly connect the mobile to MT8870.

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rahuljin

Sat Feb 02 2008, 08:27AM

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can u tell me the use of this relay ???

Ajay

Sat Feb 02 2008, 10:12AM

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relay picks up the phone.. when ring is detected.. microcontroller switch on the relay and hence phone is answered.

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rahuljin

Sat Feb 02 2008, 08:45PM

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so even without relay i hav to use ring detector circuit or not ???

Ajay

Sun Feb 03 2008, 08:25PM

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Well usually there is facility in every mobile for auto answer, if you enable it.. then you need to decide how to detect if call is activated or not..

One thing you can do is.. use auto answer and ask user to press * to start with the further work.. you can also couple microphone with controller to feed voice response..

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rahuljin

rahuljin

Sat Mar 01 2008, 11:27AM

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i have done everything !!! but i am facing a problem.
i sent the dtmf tone to other mobile then it is taken by cm8870 and output of cm8870 is obtained. then this output is given to microcontroller, and an other output is obtained at other port of microcontroller.
now my problem is that the port does not refresh after the output is obtained. i get same output untill i press another key !!!
i tried to give setb to std (in cm8870) through microcontroller !!
i also tried to refresh the port but no use !!!

[ Edited Sat Mar 01 2008, 11:29AM ]

GioppY

Sun Mar 02 2008, 04:39AM

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You have to wait the end of the dtmf tone; check the stb pin.
Something like this pseudocode

CODE:

Sub St_dtmf

         if Stb = 1 then

            mov     a,P0               ;get data from MT8870

            anl     a,#15               ;4 bit  low nibble

            lcall   conv_tone         ;convert to ascii

            Txx  =  Acc

            DtmfString = DtmfString + chr(Txx)         ;save

            do

            loop until Stb = 0          ;wait end dtmf

         endif

End sub

;

Conv_tone:

        inc     a              

        movc    a,@a+pc        ;get from table

        ret

        db      H44,H31,H32,H33          ;D123

        db      H34,H35,H36,H37          ;4567

        db      H38,H39,H30,H2A          ;890*

        db      H23,H41,H42,H43          ;#ABC