Phone basic

[Charlie123]

Hello,

I need some assistance on basic stuff regarding a small phone project.
I would like my home phone to

1) memorized 2 phones numbers(that I need to programm into it; but NOT ERASABLE)... How can I programmed these into a phone circuit ??? or what IC or ship or tool should I use ???


What will be your best suggestion.

I have some basic knowledge on electronic

Best regards/Charlie de Bolton

 

[Marks256]

I am not quite sure what you mean? You want the two phone numbers to be the ONLY numbers it will recieve? Or the two numbers will be the numbers of the phone it's self?

 

[audioguru]

30 years ago, Motorola made many phone ICs. They sold ringers, dialers and speakerphones ICs.

Now that you can buy cheap phones made in China, then nobody buys the ICs except the Chinese phone manufacturers.

Look up the circuit of an old dialer IC and make one yourself with anout 100 Cmos logic ICs.

 

[3v0]

IIRC it is still possible to dial phones using pulses. A single transistor driving a reed relay and the most basic PIC will work. Add two puch buttons and you have everything but the (simple) code.

 

[gramo]

I thought that phone key presses were DTMF(dual tone modulated frequencies)?

 

[3v0]

I thought that phone key presses were DTMF(dual tone modulated frequencies)?

DTMF is a rather new invention. In the days of phones with dials, the dial was attached to a cam that open and closed a set of contacts.

The rotary dial is a device mounted on or in a telephone or switchboard that is designed to send interrupted electrical pulses, known as pulse dialing, corresponding to the number dialed. It was invented in 1888 by Almon Strowger. The device was phased out from the 1970s onwards with the onset of Touch Tone™ dialing, which uses a telephone keypad instead of a dial. Some telephone systems no longer recognize pulse dialing by default, so now it would have to be ordered from the telephone company as a special feature, to support older customer equipment.

 

[audioguru]

My phone line has always been for "rotary dial". DTMF doesn't work with it. I refuse to pay a "DTMF fee" each month, year after year when I can dial with the switch on my pushbutton phone set to "pulse" then when the call is connected I switch it to "tone" and do DTMF banking and other DTMF functions.

 

[Nigel Goodwin]

My phone line has always been for "rotary dial". DTMF doesn't work with it. I refuse to pay a "DTMF fee" each month, year after year when I can dial with the switch on my pushbutton phone set to "pulse" then when the call is connected I switch it to "tone" and do DTMF banking and other DTMF functions.

I'm just surprised they try and charge you extra for such a basic feature?.

 

[Charlie123]

Hello everybody,

to answer Mark256;
the two phone numbers will be the only numbers that my phone will receive, the answer is; yes. What kind of device(nvram, IC,PIC) should I use.

audioguru;
tks for your suggestion

3v0;
don't really need pulses, TONE ONLY /tks

Gramo;

Will take a look today on your ref URL. /tks


Brgds/Charlie de Bolton

 

[audioguru]

The phone company in Canada has always charged about $5.00 per month fee for DTMF. In 30 years I have saved $1800.00 in fees by using "rotary dial service".

A couple of years ago the phone company tried to force everybody to use DTMF and to pay the fee. It turned into a class-action lawsuit and the court said Dey Kant Do Dat!

 

[gramo]

Gramo;

Will take a look today on your ref URL. /tks

I havent started on DTMF yet, but when I do it will be with the MT8888 for an easy interface with a micro controller

 

[Charlie123]

hello,

audioguru; did not know that ?? that is a good think to know. but this will
just complicate my work for the moment.

I went into your tutorial and this is GREAT! I looked into, from main page to end and this give me precious information, specially how to connect the PC and programm the PCI. But I need to read it again. did not get all the stuff on programm but I have a good idea how programm a PCI. Is there a way(a reference) to know wich PCI will be the best for my project? eg: PCI page description.

 

[gramo]

By PCI, do you mean PIC?

 

[Charlie123]

Hello Gramo,

yes I mean PIC !

 

[gramo]

Perhaps this **broken link removed** will help. It’s based around Proton Lite, a very powerful compiler/PIC development suit that allows you to create PIC programs and simulate them as if in real life.

Of course with anything free there is limitations, and with Proton, its functionality is limited to a couple of PIC's/and not much code length, but enough for any beginner project.

One of the PIC's you are limited too is the 16F877. This is a 40 Pin micro, and jam packed with features.

Personally I think the 16F877 is a great place to start, not only because you are simulating with it in Proton, but its pin count caters for heaps of external components.

 

[gramo]

A smaller PIC might be desirable for a smaller application like this. But the option is yours

Both will do the same job. One will provide a lot more diversity in the future

 

[Charlie123]

Hello Gramo and everybody,

tks for the ref. your very kind but I need to have a big picture before starting to programm PIC. First I need to know what components and how the will interact btwn themselve. Your 16F...I'm not sure Let me show you what I want to do:

Let say, I have 10 employees calling ONE office phone line.
But I want two of them with the phone number 457 297-1344 and 450 297-1450 to activate automatiquely a device once calling (don't want PBX involved).

My concern is how can I make these two phone numbers to be authenticate.

So I tought, If I use a MT8841(caller id) and use a comparator to compare the coming call phone number to the number stored (in this case 4572971344 and 4502971450) this should work. Am'I right?

How do you see that setup. Is one PIC can do all the work ??? Should I use a PIC (in this case wish one)? What is your best guess. tks

 

[gramo]

Hehe, one step at a time!

First you should get a PIC programmer, a PIC or two, and some simple components to power your PIC, eg;

• 5V Voltage supply circuit
• External Oscillator Circuitry

And then make some simple programs (like blinking an LED/Learn how to interface with PIC's), and work up to the diversity you require. Starting with a project like this is by no means a friendly intro to :mu: programming!

 

[Charlie123]

Hello Gramo,

tks for your advise... rode the entire web site yesterday and I have a pretty good idea on what I need to start the project...but some questions are not answer at the moment, I'm trying to evaluate and have a litle idea on what component I will need to perform my project. I know that I will need a programmer kit...etc, etc. I have a pwr supply already, I have a breadboard and to interface with PIC via JDM this is not a pbm as tutorial was very good to describe the steps and I did some led project in the past and built ADC circuit. For programmation I looked how you programmed and have a good understanding on what to do as I understant PHP and did some programmation in the past...but the tutorial cannot answer some of my questions because it is too specific.

Let say I want to save phone number into a memory...what should I use as EEPROM? Should the phone numbers be loaded to memory via binary code,HEX or direct phone number into memory via the programmation? How can I only filtered phone nmber from FSK(not the name and the date) via my MT8841. to compare on what is in my memory. Can you give me a brief idea and overview or answer previous message this will be geatly appreciated.

Brgds/Charlie

 

[gramo]

PIC micro's have anon board EEPROM to store information while they are off, or for long term access, and reading through the MT8841 datasheet breifly would indicate a Simple serial 3-wire data interface would be used between the two.