====== OVER/under ======

===== Introduction =====
In keeping with our interest in generative modular compositions, We would like a way to programmatically introduce a sense of progression. We believe we can accomplish this with a counter module. Such a module would increment or decrement an internal counter on receipt of a related trigger. When the counter rises beyond a specified limit (or drops below zero), the module outputs triggers to indicate the associated condition. 

The working name of this project is OVER/under.

===== Design =====
==== Interface ====

  * inputs
    * steps (knob)
    * steps (CV, -5 -- +5V)
    * increment (trigger)
    * increment (button)
    * decrement (trigger)
    * decrement (button)
    * enable (gate)
  * outputs
    * overflow (trigger)
    * underflow (trigger)
    * wrap (trigger)
    * percent/progress (CV, 0 -- +5 or +10V)

The module will also have some kind of display to indicate the counter's internal state, either an LCD with boxes (think Pam's Euclidean rhythm display) or a series of multicolor LEDs. 

The percent or progress CV out sends a stepped voltage based on the counter's progress to the selected step count. 

==== Software ====
A proposed pseudocode outline appears below. 

<code text>
init:
  length = 1
  counter = 0
  
  n = max length
  k = knob CV scale
  r = output range for percent out (+5V or +10V) 

loop:
  clear expired triggers
  read steps knob
  read stops CV (norm = 0V)
  length = k * [steps CV] + [steps knob], clamped to [1, n]
  counter = counter % length, do not emit wrap triggers
  read enable (norm = +5V)
  if enable > +2V and increment triggered:
    if ++counter >= length:
      counter = counter % length
      emit overflow trigger
      emit wrap trigger
  else if enable > +2V and decrement triggered:
    if --counter <= 0:
      counter = counter % length
      emit underflow trigger
      emit wrap trigger
  update interface
  set percent out to (counter / n) * r
</code>

===== Prototyping =====
==== VCV Rack ====
This project is ideal for testing within the virtualized environment offered by VCV Rack.