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View Full Version : dtmf based control help its really urgent



sudarshan
06-16-2010, 01:37 PM
hi
i have dtmf decoder circuit bought from kitsnspares
http://www.kitsnspares.com/user1/productdescription.asp?id=417

it has four bit output
i have connected it to atmega32 PORTA 0-3

iam using switch case for every key

switch(a)
{
case ---: //for key 1
case ---: //for key 2
.
.
.
)
what should be the hexadecimal case values for the each key from 0-9 and * #
is it 0x01,0x02,......
please help me it is really urgent

i have attached the dtmf output table to

rao
06-16-2010, 02:13 PM
Yes sudarshan, H is 1 L is 0 convert binary to hex, quite easy.

sudarshan
06-16-2010, 02:46 PM
ok just tell me wheather the following are correct

for key 1
L L L H binary 0001 hex 0x01 so
switch(PINA)
{
case 0x01:
lcd("key 1 is pressed");
}

for key 8
H L L L binary 1000 hex 0x08 so
switch(PINA)
{
case 0x08:
lcd("key 8 is pressed");
}

rao
06-16-2010, 05:58 PM
Looks right.

Ulhas
06-17-2010, 08:07 AM
ok just tell me wheather the following are correct

for key 1
L L L H binary 0001 hex 0x01 so
switch(PINA)
{
case 0x01:
lcd("key 1 is pressed");
}

for key 8
H L L L binary 1000 hex 0x08 so
switch(PINA)
{
case 0x08:
lcd("key 8 is pressed");
}

True only if you don't have any other inputs or pull up connected to PORT A ie your upper Nibble must be at logic 0
other wise AND it with nibble then only you can switch PINA data

shyam.sunder91
06-17-2010, 01:26 PM
hey i have a doubt with this
not regarding the code
how do u manage to connect the mobile jack to the kit
i too looking to purchace a kit like this
how should i connect the tip and ring to the input of 8870
plz give a detailed description plzz
how to identify the tip and ring plzz

allbits
06-17-2010, 04:39 PM
@shyam.

Please, for your own sake, USE punctuations. People wont even bother to read your post fully if it is not clear or confusing. I checked out your older posts, and even after asking you, you refuse to put even a fullstop in your posts. No wonder why you got little help.

shyam.sunder91
06-17-2010, 04:47 PM
@shyam.

Please, for your own sake, USE punctuations. People wont even bother to read your post fully if it is not clear or confusing. I checked out your older posts, and even after asking you, you refuse to put even a fullstop in your posts. No wonder why you got little help.


is this fine now
hey i have a doubt with this
not regarding the code
how do u manage to connect the mobile jack to the kit
i too looking to purchace a kit like this
how should i connect the tip and ring to the input of 8870
plz give a detailed description plzz
how to identify the tip and ring plzz

sudarshan
06-17-2010, 05:39 PM
Hi ,
the kit mentioned above can with the 3.5mm audio jack connected in it so i had no problem with it.

shyam.sunder91
06-17-2010, 06:39 PM
Hi ,
the kit mentioned above can with the 3.5mm audio jack connected in it so i had no problem with it.

thanks sudarshan can u plz help me here
http://www.roboticsindia.com/showthread.php/3521-problem-with-dtmf-wiring-the-jack

sudarshan
06-18-2010, 01:03 PM
True only if you don't have any other inputs or pull up connected to PORT A ie your upper Nibble must be at logic 0
other wise AND it with nibble then only you can switch PINA data

i really could not uderstand the above.
i use PORTA0-3 for input and
PORTA6-7 as output .

so can i use switch PINA

asimov_18
06-18-2010, 01:18 PM
HI , I think convertingt the binary value to hex is very straigt forward. The circuit should be using CMM8870 or an equivalent IC with 3.578 MHz crystal (thats the standard) now the hex values are as follwows
1) 0x01
2) 0x02
3) 0x03
4) 0x04
5) 0x05
6) 0x06
7) 0x07
8) 0x08
9) 0x09
0) 0x0A
.) 0x0B
#) 0x0C
A) 0x0D
B) 0x0E
C) 0x0F
D) 0x00


This is as simple as a,b,c dear.......


Asimov

sudarshan
06-18-2010, 01:24 PM
my problem with values are cleared .
but the new problem is with reading the value
for switch case
switch(PINA)
{
case ...:
}
can i use the above or not
i use PORTA0-3 for input and
PORTA6-7 as output ...

shobhitkukreti
06-19-2010, 11:39 AM
Sudarshan, i know you are trying really hard to make this circuit, but i would advise you to study a little bit of theory first.What does a nibble mean ? What is a pull up ?. Ulhas could have been a little lucid in the presentation , but he told you the way. Only if you could understand the relevant terms in the above lines, you could decipher it.