SSI Hall of Coaster-makers
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Category
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Error
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Description
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Solution
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Notable Entrant
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Schematic Errors
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Inconsistent Net Naming
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When two nodes must be electrically connected but aren't visually connected in the schematic by a single wire, naming their nets two different things and causing there to be no connection, leading to a trace not being placed.
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Check ICs to make sure all pins are routed or appropriately not connected.
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Sasha Maldonado, on ValBal Generation IV, where the chip select for an SD card was labeled "SDCS" at one point and "CS" at another.
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Wires and Pins Not Aligned On Grid
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Improperly setting the snap grid in the schematic editor, such that wires and pins can appear connected at a quick glance but not actually be connected, leading to a trace not being placed.
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Check ICs to make sure all pins are routed or appropriately not connected. Avoid setting the schematic editor snap grid to anything other than 10 [units].
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Kirill Safin, on HAB Main Avionics PoS1, where a number of pins appeared connected but were very much not.
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Routing Errors
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Sensitive Analog Traces Near Noise Sources
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When a trace carrying an analog voltage - i.e. a voltage or current sense - is routed in a way that makes it likely to pick up noise, affecting the analog value.
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Route sensitive analog lines first, shielded by ground planes when appropriate, and then be mindful of the placement of noise-inducing devices (i.e. inductors). On two-layer boards, cross traces on opposite layers at right angles to each other to minimize noise coupling.
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Sasha Maldonado, on ValBal Generation V.I, where a voltage sense line was run under and parallel to an inductor in a switching power converter, creating a small transformer and rendering the voltage sense useless.
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Silkscreen Errors
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Silkscreen Over Pads/Vias
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When silkscreen - a line, part label, etc - is place over an etched pad or a via and therefore doesn't fully print.
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Visualize the board in 3D 3 , where intersections between silkscreen and board features are more obvious.
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Sasha Maldonado, on ValBal Generation V, where multiple part labels were printed over exposed copper and so were awkwardly clipped - some to the point of being nonfunctional.
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Failure to Place Information on Board
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Not placing the standard set of silkscreen features on a board - board name, designer name(s), date, revision, sponsor logos, SSI logo. "Made with <3 in Stanford, CA" is hardly required but encouraged.
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Just do it. Seriously. Your work takes a bunch of your time. It should look good.
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Cameron Ramos, who did none of this on the Can Transceiver Board v2.
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