Thanks to everybody.
I get very usefully ideas here.
I think I am going to try to add a transistor to the common cathode, driven
by a PWM.

Cristiano


2009/12/7 Jinx <joecolquitt@clear.net.nz>

> > I was wondering if someone has an advice for a driver for a 7
> > segments display. I need to be able to adjust the brightness of the
> > display "in software", with a command. The display drivers I have
> > found so far expect an external resistor to set the brightness level
>
> Cristiano, I occassionally use the CMOS 4543
>
> http://www.futurlec.com/4000Series/CD4543.shtml
>
> http://home.clear.net.nz/pages/joecolquitt/counter.gif
>
> (sorry about the inverted colours, I'd change it but my ftp is playing up)
>
> In that circuit there would be a couple of options. Strobe the Blank
> pin (which enables the output drivers) or strobe the common cathode
> (the ground connection to the right of the LSD) via a FET. Either could
> be done with a PWM output
>
> For ICs that expect a resistor to set the current, that resistor could be
> selected from a group with a transistor or 4066
> --
> http://www.piclist.com PIC/SX FAQ & list archive
> View/change your membership options at
> http://mailman.mit.edu/mailman/listinfo/piclist
>
-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist