DTMF decoder MT8870

GIO · Guest

Hello guys!

Anyone had worked with DTMF decoder MT8870 and has an example routine ?

Thanks in advance, Giorgio

Humberto · Posted: Thu Sep 07, 2006 9:00 am

The decoder MT8870 doesn�t need any code to run. It work by itself, read carefully the datasheet and connect it as described. It decode a DTMF signal in a 4 bit HEX number as output, if you want to interpret those 4 bit you can do it with the help of a microcontroller, or not.

http://products.zarlink.com/product_profiles/MT8870D.htm

Humberto

Mark Weir · Joined: 11 Sep 2003 Posts: 51 Location: New Zealand

Hi,

The 7780 is a great chip for decoding DTMF incoming signals. It is very simple to use. I use the circuit from the application in the datasheet. The chip has a pin labelled Std at 15, this pin goes high when you have a valid DTMF signal so it can be polled or used to trigger an interrupt.The data, in BCD will appear at pins 11,12,13,14 weighted 1,2,4 and 8.

I have used this very sucessfully in several products.
You dont need any fancy code to work with this chip just monitor the Std pind and read the BCD as inputs from another port.

Cheers

Mark