vinodquilon
Member
My project (DTMF Teleremote Control) spinning around a lot of strange problems. Every now and then it occurs and after some thought
if cannot figure out, I go for Forum Thread posting. I optimize no one get bitterer by checking indistinguishable subject.
But I anticipate this would be an open place to clear any doubts (basic to advanced) of a common man around the world.
If someone getting bored, please refuse it as an unrequited topic.But I think every new post would contain some challenging bottlenecks.
Entirely different issues on same project, so I use different threads.
Now come to the point,
Look up the attachment ( many members may easily recognized it as of previous threads ).
When power up the circuit all LED s 1 to 4 turned-on (I expect all turn-off).
The problem is that, When I calling from remote end all the LED s blinking randomly for 1 sec (undesired result) and then
comes to a stable state.
But this blinking effect doesn't exist when I manually turn-on the circuit after passing first ring.
Now all LED s directly comes to the stable state without blinking as narrated below in the table.
The surprise attack is that depending upon the service provider of telephoning remote person the
stable state varies as indicated below:
OPERATOR(India) LED4 LED3 LED2 LED1
BSNL OFF ON OFF OFF
VODAFONE OFF ON OFF ON
IDEA ON OFF ON OFF
RELIANCE ON OFF OFF ON
AIRTEL OFF OFF ON OFF
Local land-line end working on BSNL line.
I doesn't believe in the supernatural effects, but there should be an evil influence.
I also tried the TOE in of DTMF IC, but after enabling DTMF Outs (after passing first ring) the
first state would be the stable state described above without blinking problems. PWDN pin also not working.
At a time subsequent to this stable state, DTMF IC obeys the normal truth table specified in the MITEL data sheet
upon different key events on remote end after off-hooking local end.
This is the third IC I have replaced, first two ones- MT8870CE,35P050C9,9004 AE
didn't work at all. Third one- MT8870CE,12579.2,9125 AE- have the above issues. Next time I will choose KT3170 !!!
Without solving these issues I can implement my project by,
1. Designing a ring counter which turn on the circuit only after passing first ring, thus no blinking problems at all.
2. Designing a tri-state buffer with decoder at output of DTMF IC. Thus #<decimal> key combination can be designed.
Circuit designed to turn on trisate for 5 sec when # key presses. During this interval I can press a decimal key,
which is assigned to a particular house-hold device. Thus turn on-off corresponding devices. One of 16 outputs of
Decoder IC will turn on at a time depends on DTMF BCD outs.
First time I didn't notice this stable state changes (as indicated in previous threads) between different operators as
in my workbench I have been using my personnel mobile phone as remote end and land line in my home as local end.
When I switched to my friends' mobile having different connection I noticed this change.
if cannot figure out, I go for Forum Thread posting. I optimize no one get bitterer by checking indistinguishable subject.
But I anticipate this would be an open place to clear any doubts (basic to advanced) of a common man around the world.
If someone getting bored, please refuse it as an unrequited topic.But I think every new post would contain some challenging bottlenecks.
Entirely different issues on same project, so I use different threads.
Now come to the point,
Look up the attachment ( many members may easily recognized it as of previous threads ).
When power up the circuit all LED s 1 to 4 turned-on (I expect all turn-off).
The problem is that, When I calling from remote end all the LED s blinking randomly for 1 sec (undesired result) and then
comes to a stable state.
But this blinking effect doesn't exist when I manually turn-on the circuit after passing first ring.
Now all LED s directly comes to the stable state without blinking as narrated below in the table.
The surprise attack is that depending upon the service provider of telephoning remote person the
stable state varies as indicated below:
OPERATOR(India) LED4 LED3 LED2 LED1
BSNL OFF ON OFF OFF
VODAFONE OFF ON OFF ON
IDEA ON OFF ON OFF
RELIANCE ON OFF OFF ON
AIRTEL OFF OFF ON OFF
Local land-line end working on BSNL line.
I doesn't believe in the supernatural effects, but there should be an evil influence.
I also tried the TOE in of DTMF IC, but after enabling DTMF Outs (after passing first ring) the
first state would be the stable state described above without blinking problems. PWDN pin also not working.
At a time subsequent to this stable state, DTMF IC obeys the normal truth table specified in the MITEL data sheet
upon different key events on remote end after off-hooking local end.
This is the third IC I have replaced, first two ones- MT8870CE,35P050C9,9004 AE
didn't work at all. Third one- MT8870CE,12579.2,9125 AE- have the above issues. Next time I will choose KT3170 !!!
Without solving these issues I can implement my project by,
1. Designing a ring counter which turn on the circuit only after passing first ring, thus no blinking problems at all.
2. Designing a tri-state buffer with decoder at output of DTMF IC. Thus #<decimal> key combination can be designed.
Circuit designed to turn on trisate for 5 sec when # key presses. During this interval I can press a decimal key,
which is assigned to a particular house-hold device. Thus turn on-off corresponding devices. One of 16 outputs of
Decoder IC will turn on at a time depends on DTMF BCD outs.
First time I didn't notice this stable state changes (as indicated in previous threads) between different operators as
in my workbench I have been using my personnel mobile phone as remote end and land line in my home as local end.
When I switched to my friends' mobile having different connection I noticed this change.
