DTMF decoder IC in smaller than SOIC-8 package?

CuriousOne

Hello.

Is there a smaller solution than SOIC-8 LM567, say in SOT-23 package for DTMF decoding?

Leon

There are some very small MCUs that could decode DTMF.

PJAllen

Of course several 567s (7) would be required for DTMF (one for each column and one for each row)

http://www.ebay.com/itm/DTMF-Tone-Receiver-Decoder-DTMF-SM2-slim-Assembled-and-tested/291204881194?_trksid=p2050601.c100272.m3467&_trkparms=aid%3D111001%26algo%3DREC.SEED%26ao%3D1%26asc%3D20140813112422%26meid%3D832a58e1f6904a9697002aa82e86f661%26pid%3D100272%26prg%3D20140813112422%26rk%3D1%26rkt%3D4%26sd%3D291204881194%26clkid%3D43051858766694834&_qi=RTM1562569

Phil Pilgrim (PhiPi)

What micro are you using it with? The reason I ask is that the Prop can decode DTMF without an external IC.

-Phil

CuriousOne

Actually I need to detect only "busy" tone, so 2 LM567 should be enough.

I want to build a device for my elder parents. Being incorporated into cordless handset, it will hang up the phone, after receiving busy signal for about 20 seconds. Since space is limited, this is why I need smaller chips. I know that prop can do DTMF natively, and there are some PICs with that function. But they need advanced programming, and I'm only BASIC enabled (Z80 ASM too), so....

LoopyByteloose

Not sure about package availability, but here is a PIC coded solution.
This doesn't take a large microcontroller to deploy.

The PICAXE has DTMF ablities.

http://www.picaxeforum.co.uk/showthread.php?12417-Picaxe-Dtmf

http://pe1grl.khds.nl/dtmf/dtmf.htm

LoopyByteloose

The MT8870 DTMF receiver chip might be what you desire.

http://www.futurlec.com/Mini_MT8870.shtml

PJAllen

I need to detect only "busy" tone..."

That's a different matter.
The 8870 only does The DTMF ("touch-tone") signals.
Two tones do not DTMF make.
The busy tone (or busy signal) isn't part of that scheme.

http://en.wikipedia.org/wiki/DTMF
http://en.wikipedia.org/wiki/Precise_Tone_Plan

You might just look for the 620 Hz component if the dial tone in your area conforms to PTP.
The old, familiar busy signal is just the dial tone. The two could be differentiated by detecting several reps.

kwinn

PJ Allen wrote: »

That's a different matter.
The 8870 only does The DTMF ("touch-tone") signals.
Two tones do not DTMF make.
The busy tone (or busy signal) isn't part of that scheme.

http://en.wikipedia.org/wiki/DTMF
http://en.wikipedia.org/wiki/Precise_Tone_Plan

You might just look for the 620 Hz component if the dial tone in your area conforms to PTP.
The old, familiar busy signal is just the dial tone. The two could be differentiated by detecting several reps.

I beg to differ on one point. Two tones do DTMF make, however I do agree there is more to phone signalling than that. Dial tone, busy signal, coin signals for payphones, and diagnostic signals were around before the advent of DTMF.

CuriousOne

I have used 8870 and 8880 with basic stamps, none of them are available say in SOIC, WL-CSP or any other space saving packaging. Remember, I have to fit all that junk into HANDSET of cordless phone.

"my" busy tone is definetly DTMF, since consists of two tones, it is output by VOIP adapter, Cisco-Linksys PAP-20.

PICaxe might be good, but requires some investment, which is not good

LoopyByteloose

Well ... wanting the smallest and the cheapest in a simple programing language is asking for quite a lot.

There are extremely tiny microcontrollers by TI that would work well, but you need to program in assembly language to use them. Some 'sweat equity' is required in learning to code the cheapest and tiniest of devices.

PJAllen

CuriousOne wrote: »

"my" busy tone is definetly DTMF, since consists of two tones,...

It's not, but feel free to get your back up all you like. Neither of those ICs will find a busy signal.
Two tones, as such, simply do not mean that's part of DTMF signaling.
They have to be the specific tones for dialing, not simply two arbitrary simultaneous tones.
I wonder why the F so many people here are so GD sensitive.
Things here get real stupid, real fast.

Have fun!

Warmest Regards,

The Antichrist

Publison

I guess you are both correct. Well..not really. I think PJ is right. I don't believe the busy signal is part of the DTMF protocol.

In North America, the Precise Tone Plan used today employs two tones of 480 and 620 Hz at 60 i.p.m. (i.e. on for 0.5 sec., off for 0.5 sec.). In the past, before the adoption of the PreciseTone system, busy signal was generally composed of the same tone as dial tone in the central office in question, interrupted at the same rate.

http://en.wikipedia.org/wiki/Busy_signal

EDIT: Or maybe it is?:

[h=2]Special tone frequencies/COLOR][URL="http://en.wikipedia.org/w/index.php?title=Dual-tone_multi-frequency_signaling&action=edit&section=4"]edit[/URL][COLOR=#555555[/h]National telephone systems define additional tones to indicate the status of lines, equipment, or the result of calls with special tones. Such tones are standardized in each country and may consist of single or multiple frequencies. Most European countries use a single precise frequency of 425 Hz, where the United States uses a dual frequency system.


EventLow frequencyHigh frequency

Busy signal (US)
480 Hz
620 Hz


Ringback tone (US)
440 Hz
480 Hz


Dial tone (US)
350 Hz
440 Hz

http://en.wikipedia.org/wiki/Dual-tone_multi-frequency_signaling

LoopyByteloose

PJ is right, even if he is so darned annoying.
In the back of my mind I have been pondering when the busy signal was added to DTMF. I guess it technically never was, but a somewhat similar process for creation and decoding is in play.

@PJ
Calling yourself "The Antichrist" isn't going make conversation any more intelligent. But thanks for catching the oversight.

@all
What I love is that problems like this just teach me more useful details. Live and learn.

PJAllen

Loopy Byteloose wrote: »

PJ is right, even if he is so darned annoying.
@PJ
Calling yourself "The Antichrist" isn't going make conversation any more intelligent.

Your BS ("participation") always precludes any such possibility.
Talk about "annoying".

Have fun!

Warmest Regards,

The Antichrist