Re: DTMF with AT2051
From: dont know (mojo_at_nospam_netscape.com)
Date: 01/18/04
- Next message: Henrik Nielsen: "Re: Flash equivalent for 12C509A"
- Previous message: Marcel-G: "AT91RM9200 SSC and I2S audio DAC"
- In reply to: Allen: "Re: DTMF with AT2051"
- Next in thread: Allen: "Re: DTMF with AT2051"
- Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]
Date: Sun, 18 Jan 2004 15:39:30 GMT
Allen wrote:
> "dont know" <mojo@nospam_netscape.com> wrote in message
> news:<2qiOb.89277$%wh.66518@news04.bloor.is.net.cable.rogers.com>...
> > Ppelectron wrote:
> >
> > > > Hi,
> > > >
> > > > Is the 2051 capable of generating DTMF like what is described in
> > > > AN655 of the microchip Apnotes? If not, can someone recommend a
> > > > cheap and easily available chip that would be interfaced to the
> > > > 2051?
> > > >
> > > > I know I can get the DTMF dialer chip from a used telephone set
> > > > but it is normally for connecting to a numeric keypad instead
> > > > of the data lines of the cpu.
> > > >
> > >
> > > DTMF generation generally requires a lot of microcontroller
> > > resources, so it really depends what else you require the micro
> > > to do whilst DTMF is being generated. I usually prefer to use a
> > > seperate DTMF chip such as the Holtek HT9201A. Yes, you need to
> > > simulate keypresses, but it really isn't that difficult.
> >
> > I have modified PCB's from a phone to do the dialing with a 8051
> > micro. Wire an opto accross a keypad, resistance is low enough
> > when the opto is on. Drive the opto's with the micro.
> > normally the keypad is arranged in a 4x4 matrix. A AT89C4051 has
> > more flash memory.
>
>
> I don't quite get it here. Are you wiring 'one' opto-coupler to the
> keypad and send out decadic pulses OR are you wiring "seven" optos on
> the column and row lines and on each digit, triggering two optos to
> send out the dtmf tones.
yes, 1 opto on each keypad. If you get a phone with a keypad to
grab the line (VISTA 350) wire an opto across that as well and you
have a remote off-hock function.
>
> I was thinking of using the line interfacing part of a modem for
> experimenting with my DTMF sending.
>
> Allen
- Next message: Henrik Nielsen: "Re: Flash equivalent for 12C509A"
- Previous message: Marcel-G: "AT91RM9200 SSC and I2S audio DAC"
- In reply to: Allen: "Re: DTMF with AT2051"
- Next in thread: Allen: "Re: DTMF with AT2051"
- Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]
Relevant Pages
|
