Nathan House wrote: > Schematic: > http://www.roboticsguy.com/images/misc/pic18f4550_tqfn_schematic.png You've got to be kidding! You are always judged by the examples of your work you let others see. The fact that you're not sufficiently embarassed by this says a lot about what kind of engineer you are (or aren't in this case), even more than the mess itself. Schematics are not only to define what's connected to what inside the ECAD software, but also to explain the circuit to humans. 1 - The pins of IC1 are in pin number order! That may save you a few minutes making the symbol once, but wastes many times that over the life of the schematic as people have to figure out what's where. 2 - Do you really need all those big fat circles with Xs thru them to show no connections (if that's what they indeed are)? Just don't connect anything to a pin and it will be obvious nothing is connected to it. 3 - It's nice to have logical flow of signals from left to right. That's not always possible, especially with complicated ICs, but at least you can put power on top and ground on bottom. You've got Vdd going every which wa= y except the one logical direction, which is up. If you'd bothered arranging power going from top to bottom, you might have noticed that D1 is backwards= .. See how taking a little care actually makes a concrete difference? 4 - Neatness counts, since it effects readability. It's even more importan= t when you expect others to see your work. Since this is of course obvious, it logically follows that not taking some care is either stupid or deliberately rude. So which is it? The vertical text and even text overlapping other parts is really sloppy an= d annoying to read. What's with the long label for J1? I don't wee what it'= s trying to tell us beyond that it's a RJ11 connector. Meanwhile the label collides with R1. Now how come you couldn't see this for yourself!? 5 - What's with all the polarized capacitors? Clearly C4 and C5 at 22pF ar= e going to be ceramic, which is not polarized. None of the other values are large enough at high enough voltage to require polarized capacitor technologies. These should all be the much cheaper and more effective ceramics. 6 - If I remember right, 20MHz crystal doesn't work with USB. Did you read the datasheet before designing the circuit? I didn't think so. Go read it= .. 7 - 330nF may be in spec for the Vusb cap, but it's definitely on the low end. Here's a case where the datasheet is misleading and actually contradicts itself. I've had private communication with Microchip about this, and you can use considerably more, like 1uF or even higher. 8 - Where is the power coming from? It says "Power Jack" in the bottom right corner, but there is no jack there nor anywhere else on the schematic I can find. 9 - What's the point of this PIC if it's not connected to anything other than the USB? As far as I can see, the only connections to other pins are to the infrastructure around the PIC. Shouldn't there be sensors, transducers, a serial port, analog inputs, digital outputs, *something*? > Layout: http://www.roboticsguy.com/images/misc/pic18f4550_tqfn_pcb.png 10 - Do I see this right? You are using a QFN package for the PIC but the other parts around it are all thru hole!!? If that's true, it's really funny! 11 - It makes sense for external connectors to be thru hole for mechanical strength, but it looks like the pads on the USB connector short to each other. This looks to be done with Eagle. Didn't you run a DRC check? 12 - It looks like there is silkscreen writing over pads in a number of places. Board houses will generally clip silkscreen to the solder mask layer, but its very sloppy to rely on this. It might hold up the board too= .. 13 - Daisy chained ground is a really bad idea. At least the local ground around the PIC should be locally connected. The PIC ground over by the crystal loops halfway around the board before connecting to the other side of the PIC. Making a single ground plane and blindly connecting all ground= s to it isn't the best, but it would be better than what you did. It appears everything is on one layer. Why not use the bottom at least for ground? ******************************************************************** Embed Inc, Littleton Massachusetts, http://www.embedinc.com/products (978) 742-9014. Gold level PIC consultants since 2000. --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .