On Wed, 12 Mar 2008, David Kelly wrote: > 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-M514 > >RI.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.
Yes I know, but it won't work with what the OP has because you can't access all of the LEDs individually. It would work if you had 3 7seg displays of course. > 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. It's not a power thing - it's the only way you can drive a triple-7 display.. -- Daniel O'Connor software and network engineer for Genesis Software - http://www.gsoft.com.au "The nice thing about standards is that there are so many of them to choose from." -- Andrew Tanenbaum GPG Fingerprint - 5596 B766 97C0 0E94 4347 295E E593 DC20 7B3F CE8C
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