All of the MCLR stuff? resistor and all?Originally Posted by dragons_fire
Chip destroyed - entirely possible it's shorted internally...
I wouldn't throw that board out just yet. There's plenty you can do with an exacto knife, fix-it-jumper-wires, and a soldering gun.when i etched this board, there is copper on the top too, and some of my pins dont match up perfectly, so there could be a short under the socket. i checked before i soldered, but i could have missed something..
Nothing wrong with ground planes, as long as they're connected to ground! It's the unconnected ones that may cause trouble. Also, a big slab of copper under a part also makes an effective heat sink, whether it's connected to ground or not. Good calls on the rest of the notes...so changes to the board now are:
vreg tab connected to output,
no more ground planes
MCLR stuff layed out better,
copper pads on top are gone, (except for the top traces)
.01 gap between pads and traces, .02 betweeen traces
more gap between Vdd and standoffs (Vss)
It's not the communications at 2400 baud that you'll have trouble with, it's those signals running at 10mhz+ hitting that 90 angle, causing a reflection, that reflection bouncing back on it's input and possibly pulling an input back low somewhere else, or something this or something that.it runs at 2400 baud, so i dont think it will have too many problems with 90 degree corners.
Don't forget, just because your PIC is only running 10mhz or whatever, each edge of each signal (square wave) is a small chunk of a wave of a much higher frequency (depending on how fast it rises and falls). The higher the frequency, the worse the problems. Suffice to say, 90 bad, 45 good enough, at least it's worked for me up to about 80mhz.
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