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Wissam Ch.
11-28-2006, 02:09 PM
Hi ,
How can i control four "7 segment displays" in a digital clock project with a basic stamp 2 .

knowing that·it takes 8 I/O pins to control one segment . ??

Thanks in advance for any help or tip.



11-28-2006, 08:52 PM
Use the MAX7219 or MAX7221 -- the former is available at the Parallax site, DigiKey and elsewhere. The latter can be ordered directly from Dallas Semiconductor.

www.parallax.com/detail.asp?product_id=603-00001 (http://www.parallax.com/detail.asp?product_id=603-00001)

The chip drives up to 8 LED digits (64 LEDs) with just 3 pins and one resistor for limiting current to all segments. It's a way cool chip.

When the going gets weird, the weird turn pro. -- HST

Wissam Ch.
11-28-2006, 09:06 PM
Thanks a lot .

Chris Savage
11-28-2006, 10:06 PM
·· See the following link for code and a schematic that shows the MAX7219 being used in a clock with 6 digits.· The IC can handle up to 8 digits.· Take care.


Chris Savage
Parallax Tech Support