Quote:
Originally Posted by Browzilla
And if I did manage to get it into clothing, I was hoping to produce several more.
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Have you seen the shirts on
Thinkgeek? Possible inspiration there... there are a few other models besides the wi-fi detecting shirt.
You may also want to consider a surface mount package for a clothing application... all PICs are available in surface mount packaging. I will pass you on to others for tips on doing it as I've stuck to good old through-hole DIP stuff for everything I need to do, but I understand simple surface mount isn't that hard if you have a good soldering iron and a steady hand.
I'd say the best way to see what a PIC can handle in regards to current draw (they might actually mean it when they say there is a 200mA limit... I haven't driven more than about 10 LEDs at a time off a 627a so couldn't tell you for sure) is to try it. If you can't light up all the LEDs at once, you could always increase the value of your resistors to bring the current draw down a bit. The LEDs won't be at peak brightness then, but should still be pretty darn close to it.
As a point of general interest, while I am sure this fits in to the "not exactly great practice" category and several people will happily explain why this won't work, you can run several LEDs directly off a PIC running at 5v without any resistor between the LED and ground. It would be a conservative estimate to say that my students have done this on over 200 PIC 16f84, 16f84a, 16f627 and 16f627a chips without any problem. If you were to run your PIC on 3V (2xAAA batteries perhaps?), it may be possible for you to hook up all your LED leads directly to the PIC and back to ground without the need for any other components.
And if I'm wrong and you fry the PIC... you're out two bucks. Give it a try!
That's one thing I love about the PICs... not only are they tough little chips, but they are cheap, cheap, cheap!
Jason