I am trying to make some 2x2 elevator doors for my piston elevator in minecraft and while I have all the mechanics in place I'm struggling to make the timing circuit right.
Initial setup: doors closed. B denotes a block, P denotes a piston
[B1][B2] [P2][P3] [P1]
Piston 2 pulls block 2
[B1] [B2][P2][P3] [P1]
Piston 1 pulls block 2
[B1] [P2][P3] [B2] [P1]
Piston 3 pushes piston 2
[B1] [P2] [P3] [B2] [P1]
Finally, piston 2 pulls block 1
[B1][P2] [P3] [B2] [P1]
This process is then reversed for door closing.
This method for pulling 2 blocks back each by one block works just fine when all four actions are triggered manually, but I want to now create a timing circuit that will run all four actions sequentially when turned on, then run them all in reverse when turned off. Essentially what I need is a last-in, first out order like a "stack" in computer science. Any suggestions for a timing circuit that would accomplish this?