Making an Analog Output with Diecimilla Board?


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 site, it has been duiscussed in the forum.

Melis posted this a while back

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.