>>>READER-TO-READER QUESTIONS AND ANSWERS
been written. The same books on C and BASIC for
computers will apply to microcontrollers with some
exceptions. If you want to dive into assembly programming
for microcontrollers, there are few places to learn it other
than online tutorials and the assembler reference from the
manufacturer. Nearly every microcontroller has its own
assembly language, each with its own syntax (what you
type to tell the device what to do). For PIC microcontrollers,
there is an excellent beginner’s guide to PIC programming
2004.pdf. Similar guides for other microcontrollers can be
found by searching the Internet.
Los Gatos, CA
[#1072 - January 2007]
I'm looking for a phone call screener that would allow
me to enter phone numbers of acceptable callers that would
ring the phone, but give all other calls a greeting and an
option to leave voice mail.
Does anyone know of a commercial product, kit, or
#1 A product that can do exactly that is the "Person-to-Person" from www.interceptorid.com. It has a few other
features, too. The user manual is available online so you can
check it out in more depth.
#2 There are several commercial products: www.digi
tone.com/Call%20Screener.htm and www.buyreliant.com
Here is a link to a project that could be easily adapted
to your needs: www.jandspromotions.com/philips2005
There is a link to download the entire project including
#3 I put together two versions of a PIC and a Caller ID
receiver chip to make almost what you are looking for.
My first circuit has your line and answering machine on
the input and the 'protected' phones on the output. Over
200 numbers can be programmed in the "allowed" list.
When the line rings, the phones are disconnected and
CID data is collected at the end of the ring. Date, time,
name, and number data is collected. The name and number
data is printed on a 2x16 display and the number is
compared to the stored data. If a match is found, the relay
connects the phones and the line 'rings' the phones. If there
was no match, the relay keeps the phones disconnected
and lets your answering machine take the call.
My second version has four relays. The first, "relay 0,"
handles unknown and unprogrammed calls. The other three
are activated by the 11th digit entered while programing the
"allowed" numbers. You could connect one machine for the
teens, one for your spouse, and one for you. Each could
retrieve their own messages without hearing messages
directed to others.
More machines could be added by changing the
PIC16F876 to a PIC16F877 — 28 pins vs. 40 pins — and
adding the needed code in the program.
If you are interested, I can be reached at dhewett
#4 You should look at the Globalinx personal communicator manager. If you go to www.digitone.com/ you will
see some options. I bought one and I am demanding more
of it than you. For you, it should do the trick nicely. You can
program in individual numbers, or partial numbers, to allow
or hang up on. You can tell it to store the last number that
called in as an accepted number. You can record a greeting
on the device that only those not accepted will hear, and
then they can be sent to the phone machine (that you must
provide). The ones that are accepted are allowed to ring on
the house phones without the message.
Depending on how you set it up, you may need a
second answering machine for those people (although I use
a two-line adapter so both types of calls go to a single
machine). If you want Caller ID, you have to put up with the
phones ringing two times, to allow the CID data to reach all
your phones. This is also programmable. To do more
research, try an Internet search on call managers.