Typically on a new hardware design I'll write throwaway code that exercises all outputs. You use this to verify the schematic. Maybe half the time that code e

Typically on a new hardware design I'll write throwaway code that exercises all outputs. You use this to verify the schematic. Maybe half the time that code evolves into an API/HAL that the final application will use. Many times it also becomes code for manufacturing test (burn in with the test code, then reflash with final production firmware right before boxing) Starting out with application code on top of a brand new design will lead to madness. Take it in smaller steps.