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bigjosh / SimpleNeoPixelDemo

A demonstration showing how easy it can be to drive WS2812 NeoPixels
MIT License
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Demo sketch (SimpleNeopixelDemo.ino) does not compile for some pins with "impossible constraint in 'asm'" error. #19

Closed Araris closed 3 years ago

Araris commented 3 years ago

Hi Josh,

Thank you for the opportunity to work with WS2812 without libraries. But, when I try to change the control pin, for example,

// Mega D14:

define WS2812_PORT PORTJ

define WS2812_DDR DDRJ

define WS2812_BIT 1

or // Mega A10 (D64):

define WS2812_PORT PORTK

define WS2812_DDR DDRK

define WS2812_BIT 2

, in some cases I get a compilation error "impossible constraint in 'asm'".

A similar problem is described in https://forum.arduino.cc/t/passing-port-and-bit-as-parameters-to-asm-block/584236/8 , but, unfortunately, I did not find a solution that I understood there. I hope for your help, thank you.

bigjosh commented 3 years ago

This code is specifically for an UNO. It would take significant work to make this code work on boards significantly different than the UNO. See...

q: this code does not compile for my not-arduino-uno board

Araris commented 3 years ago

Thank you for the quick and comprehensive answer.