In my efforts to interface with a quadrature encoder using SPI, I discovered:
If I use Atmel ICE debugger + Atmel Studio and program UNO using either ISP, debugWIRE, or avrDude, the execution is not as expected.
It however works correctly if I use Arduino IDE to upload the code.
Same exact code!
Have you folks seen this before? I discovered after I spent a week debugging the code and then decided to suspect the unthinkable... the debugger.