>Hi all, > >I want to make myself a UV exposure box for making PCB's. >I need to design a PIC timer board that is capable of >counting down any where from 9mins & 59secs, I want to drive >3 7-Segment displays and be able to set the timer by >turning a pot which is processed by an ADC on the pic. Do you want to do it the easy way or the easier way? I do a lot of projects that require both / either lots of ins or outs. I use shift registers - it takes a few more parts but the board layout tends to be easier, as is the software. If you are driving LED displays, choose common anode types. Connect the segments and dp to the 8 outputs of a 74hc595 SR thru 100R resistors. Connect the anodes of the displays to a 4V supply - I use lm2575 simple switchers but you can use anything you want. Or - you could use 150R resistors and run the displays from your 5V supply (resistors run hotter). You cascade the shift registers and need only 3 lines to talk to them. You can also use 2 of those lines for other purposes, such as reading switches or reading from a parallel / serial SR. dwayne Dwayne Reid Trinity Electronics Systems Ltd Edmonton, AB, CANADA (780) 489-3199 voice (780) 487-6397 fax Celebrating 16 years of Engineering Innovation (1984 - 2000) * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * Do NOT send unsolicited commercial email to this email address. My posting messages to Usenet neither grants consent to receive unsolicited commercial email nor is intended to solicit commercial email.