Arduino Forum

Using Arduino => Displays => Topic started by: cheyenneguy on Jan 18, 2013, 11:06 pm

Title: Touchtone - DTMF numbers to LCD Display
Post by: cheyenneguy on Jan 18, 2013, 11:06 pm
Hello all, I need to display digits from my touchtone telephone to a 16x2 LCD display.  What is the best way to do this?  I have looked at the Arduino Uno board with the CM8870 DTMF decoder chip, is this the best way to do it or does anyone have any other ideas?  Thank you and please respond.

Title: Re: Touchtone - DTMF numbers to LCD Display
Post by: Deltac0 on Jan 18, 2013, 11:17 pm
Probably easiest way would be an Uno and some 1602 lcd (keypad) shield. You can find these fairly cheap from eBay and China.
Title: Re: Touchtone - DTMF numbers to LCD Display
Post by: floresta on Jan 19, 2013, 12:21 am

Probably easiest way would be an Uno and some 1602 lcd (keypad) shield. You can find these fairly cheap from eBay and China.

That won't quite do the whole job since, as the original poster mentioned, a decoder chip is going to be needed as well.  The output of a DTMF decoder chip is typically four binary bits for the data and another bit to signal that valid data is available.  So your software will have to look for the data valid bit, read the binary data, convert that data to ASCII, and send it to the LCD.

I wouldn't recommend a combination LCD/Keypad shield since there is no need for the keypad.  Have you searched for a DTMF shield?

It's all quite straightforward and should be easy to implement once you get the hardware figured out.

Don