LED display segment flashing sequence

[john1]

Hi,

I'm trying to find out a bit about those little led displays which
flash around the characters quite quickly, the type i'm thinking of
are usually clock or watch displays, they flash the segments in
rotation to form the number display.

I think they do it like that to get it brighter, cos if they just
light the segments to make the numbers its not so bright for some
reason.

I want to find out the order that they flash the segments.
Or anything about the way they flash the segments.

John

 

[RODALCO]

Multiplexing

Do you mean multiplexing the display ?

 

[john1]

Yes, i suppose it is multiplexing ....

Do they just light one segment of the display at a time ... ?

 

[Sceadwian]

Multiplexing isn't done to control brightness it's done to decrease the number of I/O pins required to control a large number of LED/LCD segments. Look up Multiplexing and CharliePlexing on Wikipedia.

 

[john1]

Ok, will do.

John

 

[john1]

I had a look through the Wikipedia articles on multiplexing and charlieplexing,
they are more of a sort of overview of the principles than anything specific.

I am inclined to think that the multiplexing set-up for the four characters of
a 24HR display would probably be across all the segments involved, rather
than for each character.

If i can get the MX frequency down nice and low, i may be able to see it
clock around all the segments one after the other.

I'll see how i get on,
Cheers, John

 

[Sceadwian]

You can use a digital camera at different shutter speeds, just take a LOT of pictures, you should be able to put together the sequence yourself, as long as the switching rate isn't too high.