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I've gotten a lot of mileage out of manufacturers tech publications. TI, Atmel, Microchip, etc. have a lot of generic "how to design a device to do x" reference design papers that are really useful. Furthermore, if you don't know how to lay out a certain device, the manufacturer is usually more than eager to offer advice over email. Finally, your board shop probably has tons of experience testing all sorts of designs. When in doubt, ask! Many places are proud enough to just dump everything they know on ya! Otherwise I look at other boards and try to figure out why the designer choose to do what he or she did. I think in most cases up to 1mm of slew (difference in trace length) is allowed for USB data. For high frequency signals, you just need to make sure that the impedance of the traces are matched, that it is shielded somewhat, and that if it's a differential signal, that the signal arrives at the same time (i.e. the traces are nearly the same length). Trace width and spacing is generally determined by the current needed and the voltage applied, respectively. I don't really have any formal training either so any corrections are welcome. Here is some USB reference stuff: http://www.usb.org/developers/docs/hs_usb_pdg_r1_0.pdf dougdrums fucked around with this message at 19:38 on Oct 3, 2016 |
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Oct 3, 2016 19:20
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| # ¿ May 16, 2024 11:29 |
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