7 Segment Display - Serial Multiplexing

Gorilla

I have a couple of common anode 7 segment displays, some 74HC595 registers, and a DS1302 clock chip & a Basic Stamp 40 pin module. I want to make a clock for fun and I have no idea how to begin. Programming shouldn't be an issue as I am okay with writing code, its the hardware design that I need help with. I want the displays to be bright and have a potentiometer to control the brightness. I guess what I am getting at is how do I control the displays serial with three pins and still maintain brightness?

RiJoRi

http://pdf1.alldatasheet.com/datasheet-pdf/view/12198/ONSEMI/74HC595.html

I believe you could daisy-chain the 595s (SQ(H) to A), and clock out the n*8 data bits. Once that is done, clock the Latch Clock pins, which will load the latch. Tie /OE low so the display does not tri-state.

--Rich

Gorilla

Got 8 7 segment displays multiplexed using one 74hc595 they all appear to be on however the brightness is dim if I slip a transistor in there will that help?

Tymkrs

We made a clock though we didn't put in a pot to change the LED brightness:

http://youtu.be/nNH_tUJUI7M?hd=1

With 7 segment LED displays and 595s - hope this helps? The code we used is also available here (though for the Propeller):

http://www.tymkrs.com/forum/viewtopic.php?id=128

Mike G

Gorilla wrote:

Got 8 7 segment displays multiplexed using one 74hc595 they all appear to be on however the brightness is dim if I slip a transistor in there will that help?

Gorilla, post a schematic of your setup with source code.