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Jim The Cactus

Member Since: March 25, 2009

Country: United States

  • I’ve done some digging here and on Adafruit’s website with no luck. Is there a mechanical drawing of this board available? If not, what is the inner diameter of the mounting holes and accounting for mechanical tolerances, what is the largest diameter fastener head that will fit on the topside of the board?

  • Normally the assumption that they’re the same resistance would be a bad idea as this is almost never the case. However, this system is likely self stabilizing, since a mismatch in the current is likely to bring rise to a mismatch in heating, and subsequently keep the two approximately in balance. Nevertheless, I don’t think it’d be safe to say that two in parallel will work without doing a sensitivity analysis on both variations in the resistance and variations in the thermal coefficient; there may be unstable combinations, or combinations that are stable with a cutoff point significantly less than 500mA.

  • Magic indeed! I’m using a different approach for the RST (pull low as soon as possible, hold low for 100ms, then set high and continue) just as a matter of making sure I get a clean boot, but otherwise I end up using your init sequence verbatim. Saved me a ton of work since I’d been fighting with it for two hours.

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