From 2006.igem.org

The step-by-step procedure

Here you can find a detailed description of the state transitions that occur in the counter. The counter has four states, R1 to R4.

• start state

S is active, R1 is active

• transition to state R2

S is deactivated, R1 is still present (but fading) and represses R4. R2 gets produced

• state R2

S is inactive, R2 is active

• transition to state R3

S is activated, R2 is still present (but fading) and represses R1. R3 gets produced

• state R3

S is active, R3 is active

• transition to state R4

S is deactivated, R3 is still present (but fading) and represses R2. R4 gets produced

• state R4

S is inactive, R4 is active

• transition to state R1 (start state)

S is activated, R4 is still present (but fading) and represses R3. R1 gets produced

• ...and we return to the start state

S is active, R1 is active