Is this a gray code, except for the innermost?

Or, no... Gray codes normally have their last row go like that eh? Interesting.

@rainwarrior @foone I believe the innermost row - combined with the next one - is a direction encoder. So you can tell which direction the thing is spinning by comparing the phases of the two.

@TomF @foone What I realized is that a quadrature direction encoder is also the upper 2 bits of a Gray code, so it's actually the same thing.

I don't have a great intuitive reason for why it "looks" like the pattern breaks in the last row, but thinking about every column needing 1 bit to flip: the "extra" flip in the top row fills in the gap where everything else has gone to 0 to fill out the sequence of 2^6 values.

@rainwarrior @TomF @foone

@rainwarrior @foone No no you're right - both the last two levels have 6 set bits and 6 clear bits - the final inner ring is NOT part of the gray code - because if it was, you can't tell direction from it.