Dave Tweed schrieb: > Spehro Pefhany wrote: > >> Quoting lk : >> >>> i am wondering if my selfmade TQFP 80 adapter is working well. >>> Maybe You can just look at the picture and tell me if it is basically >>> possible to get it to work with such an adapter. >>> Of course there are no hazards! >>> I ve red that the oscillator should be as near to the OSC pins as >>> possible. Using that adapter it cant be close at all... >>> I already have run a simple LED blinking program on that chip, but am >>> not sure if everything worked well. >>> Is there generally the possibility of crosstalk et cetera? >>> There are not much information i am giving You, but maybe You can give >>> me some advise by just looking at the picture. >>> >>> http://home.arcor.de/luka5/DSC06977.JPG >>> >> Traces are pretty narrow-- it might be a good idea to widen the Vdd/Vss >> traces and maybe add a bypass cap or two near the TQFP, even if you need >> to add wire jumpers. >> > > Take it a step further than that, even. Instead of a "totally generic" > QFP80 adapter, make one that's specific to the chip (or family of similar > chips) insofar as providing the power and ground connections, bypassing, > crystal/oscillator, reset and a programming connector. This (once debugged) > will make all of these non-issues in any particular application. > > You might check out Stuart Ball's article, "Prototyping with QFP Parts", > in Circuit Cellar #218 for further thoughts about this approach: > > http://www.dtweed.com/circuitcellar/caj00218.htm#3698 > > If you want to plug it into a white breadboarding socket, consider having > the adapter span four rows rather than just two. This would make it about > 2" square rather than 4" long. Obviously, this means that half of the > connections would need to be made before you plug the adapter into the > socket, but if the pins are long enough, this shouldn't be too much of a > problem. > > x x x x x x x x x x x x x x x x x x x x x x x x x x x x > > x x x x x x x x x x x x x x x x x x x x x x x x x x x x > > x x x x x x x x x x x x x x x x x x x x x x x x x x x x > > x x x x x x x x x x x x x x x x x x x x x x x x x x x x > +---------------------------------------+ > x x x x|o o o o o o o o o o o o o o o o o o o o|x x x x > | | > | | > | | > | | > | | > x x x x|o o o o o o o o o o o o o o o o o o o o|x x x x --- > | | ^ > x x x x| |x x x x | > | | | > x x x x| |x x x x | > | | | > x x x x| |x x x x | > | | | > x x x x| |x x x x | > | | | > | | | > | | | > | | Make > Power x x x x| |x x x x this > Rails | | length > (opt.) x x x x| |x x x x match > | | your > | | setup. > | | | > | | | > x x x x| |x x x x | > | | | > x x x x| |x x x x | > | | | > x x x x| |x x x x | > | | | > x x x x| |x x x x | > | | v > x x x x|o o o o o o o o o o o o o o o o o o o o|x x x x --- > | | > | | > | | > | | > | | > x x x x|o o o o o o o o o o o o o o o o o o o o|x x x x > +---------------------------------------+ > x x x x x x x x x x x x x x x x x x x x x x x x x x x x > > x x x x x x x x x x x x x x x x x x x x x x x x x x x x > > x x x x x x x x x x x x x x x x x x x x x x x x x x x x > > x x x x x x x x x x x x x x x x x x x x x x x x x x x x > > With regard to your existing adapter -- How well does the chip run when > configured with its on-chip oscillator? Try writing some small test > programs in that mode to exercise the I/O and pin down what is or is not > working. > > -- Dave Tweed > I can not access the article. There is no link at the site.. -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist