Arduino is to commercial embedded development as what Javascript is to Java.

I had the first Arduino model with a COM port bought to me by my late mother to spike my interest into computer stuff when I was in high school.

I grew a bit over confident with what I can do, when on my first job I went on to fix an MP3 player firmware so it don't crash from Russian in ID3 tags.

I told the boss the fix is trivial, then it took me 3 month to find out that whatever you knew of garden variety C++ is not working in the world of hardcore C, and that hardware needs control down to clock cycles, registers, and assembly instructions. It was a sink, or swim experience.