Impossible constraint in 'asm'

[azkara22]

I am trying to use the ws2812 code for AVR with a ATtiny3217 but I get "Impossible constraint in 'asm'" error along with "asm operand 2 probably doesn't match constraints" warnings. The error looks like it's coming from the following instruction, but I can't get it work.

"I" (_SFR_MEM_ADDR(ws2812_PORTREG)

[cpldcpu]

Did you define a port register that is part of the I/O region?

[azkara22]

I have just found that the PORTC register that I am using is out of the I/O region. The solution in my case has been to use the VPORTC_OUT register that it is on that region. Thank you for the response anyway.

[Sponge5]

Hi, is there a way to use a register outside the I/O region? In my case I need to use PH5 on ATMega2560. In iomxx0_1.h PORTH is defined as _SFR_MEM8(0x102).

[Sponge5]

The way I understand this is to replace out instructions with sts and fiddle with the amount of noop's. I'll probably resort to rewiring the board 😅

[cpldcpu]

Have a look at the Arduino version. It actually uses sts for port access.

https://github.com/cpldcpu/light_ws2812/blob/master/light_ws2812_Arduino/light_WS2812/light_ws2812.cpp

[cpldcpu]

Version 2.5 should fix this issue.