Making an Analog Output with Diecimilla Board?

Hello,

I am working on a project in which I need to output an Analog signal between 0-5V. I was able to develop a 3rd order low-pass filter to achieve this using a PWM output from the microcontroller, but it will not work with the 490hz PWM output frequency that the Diecimila board provides (the low-pass filter requires 10kHz or 20kHz). I have two questions:

  1. Is there a way to change the 490hz frequency using programming or additional hardware so that it could match the 10kHz or 20kHz I require, or

  2. Does anyone know how to make an analog output from 0-5V from the diecimila board using additional hardware?

I appreciate any help anyone could provide.

Thanks! :)

You could always use a DAC (Digital to Analog Converter).

There are a lot of them, with different resolution and voltage handeling capabilities. They are not very expensieve unles you need very high precision and high voltage handeling.

I think there is some way to change the PWM frequency, try to use Google to search the Arduino.cc site, it has been duiscussed in the forum.

Melis posted this a while back
http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1203052678/1#1

Does your analog voltage need to change quickly? If not, why not just scale your already designed circuit for 490 Hz? You could make your filter capacitors about 20 (10000/490=20) times bigger.

I suppose you could use the 490 Hz PWM output to gate a 10kHz oscillator (555 timer?). The output of the filter might have some ripple, depending on load.

Just ideas. Can't be too specific without more details.

Good luck.