Re: [avr-chat] ATmega88 + triple 7 Segment Display (CC)

[David Kelly]

On Tue, Mar 11, 2008 at 08:53:38PM +1030, Daniel O'Connor wrote:
> >
> > - Wire each 7 segment display to a digital 8 bit latch.
> > - Use one data port to send your seven bits of segment data to all
> > three seven segments via a bus

[...]
 
> I don't think that will work with this because it's 3 7 segment
> displays ganged in parallel.
> 
> The latch idea would work for 3 separate 7 seg displays, however it's 
> probably more sensible to refresh each one frequently (fewer parts 
> needed).
> 
> If the OP has something like this..
> http://pdf1.alldatasheet.com/datasheet-pdf/view/168057/ETC/LDT-M514RI.html
> (although common cathode instead)
> 
> Then they will need to update each separate display often enough so
> the user doesn't see any flicker (50Hz+).

Driving the LED with a latch doesn't flicker, even if its updated once
every 5 minutes. All segments which are illuminated are driven by an
output bit on the latch.

When one is operating with a limited power budget and for some reason
must drive LED display not LCD then one can save power by multiplexing
where only one segment of the display array is driven at a time, driven
hard and fast moving on to the next before the eye notices. This is
common with LED calculators and watches.

-- 
David Kelly N4HHE, address@hidden
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Whom computers would destroy, they must first drive mad.