samd: neopixel: Fix neopixels after #2297 #2363
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@theacodes can you let me know if this works for you? |
This adapts the "inline assembler" code from the UF2 bootloader, which in turn is said to be adapted from the arduino neopixel library. This requires the cache remain ON when using M0, and be turned OFF on M4 (determined by trial and error) Testing performed on a Metro M4: * measured timings using o'scope and found all values within datasheet tolerance. * Drove a string of 96 neopixels without visible glitches * on-board neopixel worked Testing performed on a Circuit Playground Express (M0): * Color wheel code works on built-in neopixels * Color wheel code works on 96 neopixel strip As a bonus, this may have freed up a bit of flash on M0 targets. (2988 -> 3068 bytes free on Trinket M0) Closes: adafruit#2297
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Yep, works for Sol boards. :) |
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FWIW - fixes my grandcentral_m4 and metro_m4_airlift -- Thanks! |
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How does this work on a 48mhz core and a 120mhz core with the same delay values? What would happen if we changed the SAMD51 clock up to 180mhz? |
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We chatted on Discord and assume that the delays work on both due to the disabled cache on the SAMD51. |
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This adapts the "inline assembler" code from the UF2 bootloader, which in turn is said to be adapted from the arduino neopixel library.
It also ensures that the timing-critical code is also aligned with a cache line, so it should not be sensitive to changes in unrelated code like the old version was.
This requires the cache remain ON when using M0, and be turned OFF on M4 (determined by trial and error)
Testing performed on a Metro M4:
Testing performed on a Circuit Playground Express (M0):
As a bonus, this may have freed up a bit of flash on M0 targets. (2988 -> 3068 bytes free on Trinket M0 when I built locally)