Introduction
From 2006.igem.org
Contents |
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
breakdown into modules
The counter can be partitiond into two (fairly) independent devices:
- Input Module
- NOR Module
Both are designed as PoPS input - PoPS output devices (as specified in the MIT nomenclature)
Input Module
In this device, we want to capsule the path from S to the R's:
If we leave away the parts that don't belong to the Input Module, we are left with
As an abstract model the Input device looks as follows:
One of the outputs (PoPS OUT1) should be high and the other (PoPS OUT2) low when the PoPS IN is high and vice versa when PoPS IN is low.