boards/adafruit-itsybitsy-m4: turn off APA102 LED on startup #19357
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benpicco
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Does this still work with LTO? It looks like the overhead of a function call is enough to not have the SPI clock too high, but wit LTO enabled the SPI clock may be well out of spec. |
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Yes I tried with and the LED still gets turned off. |
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I'm still worried that optimization in the GPIO driver might result in timing issues. But if you add a comment to ease debugging in case this indeed happens, I'm fine with the ostrich algorithm on SPI clock generation here :) |
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maribu
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Mar 16, 2023
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bors merge |
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Contribution description
adafruit-itsybitsy-m4comes with a serial APA102 that is left on by the bootloader.It's really bright and the only way to turn it off is by communication with it through it's SPI interface.
We have a proper driver for it, but pulling that in unconditionally feels wrong.
Instead just bit-bang the simple protocol on startup set all colors + alpha to 0.
Testing procedure
adafruit-itsybitsy-m4no longer glows blindingly pink.tests/driver_apa102still does it's fadingIssues/PRs references