Post B5VerMjLFFyvJgP9LE by river@toot.cat
 (DIR) More posts by river@toot.cat
 (DIR) Post #B5VeE3thKdF7c5VVdw by niconiconi@mk.absturztau.be
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       1/2-layer PCB routing hack: a signal is stuck under a microcontroller? Fan it out via an unused GPIO pin set to high impedance. #electronics
       
 (DIR) Post #B5VerMjLFFyvJgP9LE by river@toot.cat
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       @niconiconi You can also insulate the pin with soldermask. Not sure how reliably though.
       
 (DIR) Post #B5VerN1QA2RYDkraWO by river@toot.cat
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       @niconiconi Mask and silkscreen.
       
 (DIR) Post #B5VerNC3WUwykjq568 by niconiconi@mk.absturztau.be
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       @river@toot.cat Yep, everyone thinks it's a "cheap trick". At least my solution is deterministic.
       
 (DIR) Post #B5VgKJPSlnfxMzTOkK by niconiconi@mk.absturztau.be
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       @bbeaker@toot.community If the GPIO goes into the MCU anyway (you need it at the opposite side), it would just be an additional regular CMOS fan-out for the source, like 5 pF to 10 pF.
       
 (DIR) Post #B5VgtHLWQyi96aIrb6 by niconiconi@mk.absturztau.be
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       @bbeaker@toot.community Yep, can be used for the source termination resistor as well, if it's going to be used as an output later.
       
 (DIR) Post #B5ZZA47CrDoNzZwMk4 by niconiconi@mk.absturztau.be
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       Just make sure it's documented when you use this hack... #electronics
       
 (DIR) Post #B5ZmtC01gp4wscQkrY by vogelchr@chaos.social
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       @niconiconi what does your “two arrows” symbol indicate? Do you have a nice list of other icons you use to indicate… things … on pins?
       
 (DIR) Post #B5ZmtCC4y0ihU04NeK by niconiconi@mk.absturztau.be
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       @vogelchr@chaos.social “two arrows” is a KiCad-specific feature, which means multiple candidate functions were entered for this pin (e.g. GPIO, UART, I2C, ...), and can be interchanged in a special menu in the schematic editor.
       
 (DIR) Post #B5ZnINogtI7mln8l3Q by vogelchr@chaos.social
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       @niconiconi oh my, … mind blown. Using Kicad for years but never stumbled upon that one 🤯 - Thanks!
       
 (DIR) Post #B5ZnIO8XhU0JlMQbzs by niconiconi@mk.absturztau.be
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       @vogelchr@chaos.social I think it's a new feature (added in KiCad 8 or 9? not sure).
       
 (DIR) Post #B5aDUNxcmKJnV3hcye by salkinium@chaos.social
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       @niconiconi why not remove those pads entirely? Then the pin won't be soldered.
       
 (DIR) Post #B5aDUOBRwvNSBwAfWi by niconiconi@mk.absturztau.be
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       @salkinium@chaos.social The trace of the unrelated signal still goes under the pin, and solder mask / silkscreen insulation is not 100% guaranteed, meanwhile a high-impedance input setting is 100% guaranteed.
       
 (DIR) Post #B5aDhgcugqx59jMEjY by funkylab@mastodon.social
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       @niconiconi @vogelchr oh that looks useful
       
 (DIR) Post #B5aDhgpfvP9znJKQcq by niconiconi@mk.absturztau.be
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       @funkylab@mastodon.social @vogelchr@chaos.social I found some definitions are not very useful, the alt function names are untested, and almost always use a full name, some are too long to fit inside the box, necessitating manual editing anyway. Still, a nice reference to check when you need to see which pin does what.
       
 (DIR) Post #B5aE5Ovs81Z7EDX8N6 by doragasu@mastodon.sdf.org
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       @niconiconi You could be naughty and instruct the firmware dev to set them as output '1'. Will not burn but can be dangerous 😅
       
 (DIR) Post #B5aE5PICmzQiLTyyBM by niconiconi@mk.absturztau.be
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       @doragasu@mastodon.sdf.org I think that would probably improve the power integrity of the IC. The external VDD is fed back into the silicon via the GPIO push-pull driver, reducing impedance. But the GPIO pins may not be rated to sink current even if it's transient only, so yeah, not recommended.