Not sure if you realize it yet, but the pic will not handle the current when used as a "digit enable" if all segments are on.. To get fancy there is a serial chip that handles the decoding, multiplexing and driving for eight seven segment (plus decimal point) or 64 indivudal led's. It is max7221 by Maxim. Be aware it only works for common cathode type displays. http://www.maxim-ic.com/quick_view2.cfm/qv_pk/1339 Bill ----- Original Message ----- From: "Shawn Yates" To: Sent: Wednesday, June 08, 2005 12:34 PM Subject: [PIC:] Flicker Free Hopefully this is a simple one... I am using one output port on a PIC to drive the segments several 7-segment LED's by switching their common pin through another port. How long do I need to leave any LED on in order for it to light up and be detected by the human eye? How quickly go I need to repeat that in order for the display to appear to be flicker-free (or very minimum flicker anyway)? Thanks. Shawn -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist