Nv Networks

From BEAM Robotics Wiki

A single Nv neuron is basically of no use. They need to be connected to build networks:

Now, if you step the input from 0 to 5 Volts, the first neuron's output will drop to 0 Volts (this neuron is now "on"); this transition will rapidly drain the second neuron's capacitor, resulting (after a delay) in a 5 Volt output from it (the second neuron is now "off").

If the input voltage is now dropped back to 0 Volts, the first neuron's capacitor will drain, resulting (after a very short delay) in a 5 Volt output (the first neuron is now "off"). This will cause the second neuron's capacitor to charge, and (after a short delay) we will see a 0 Volt output from it (the second neuron is now "on").

You can keep at this, adding neuron to neuron, eventually tying the output of the last neuron to the input of the first. This ring of Nv neurons is just one type of Nv Net, although more complex networks have been built.

Nv Nets generate square waves with varying duty cycles from each Nv neuron, like this: square waves

Again, Nv neurons use negative logic, so in this graph, "on" is denoted by low (essentially zero) [[]voltage]], and "off" is denoted by high voltage (Vcc, usually 3 - 5 volts). Each Nv neuron is generating its own square wave; the duty cycles and phasing between the neurons' waves is determined by the details of how the circuitry is interconnected. This behavior can be used to drive a number of devices (but more on that later).

Meanwhile, as things are left running, the little "on" (low) wave moves around the Nv net. This wave (typically called a Process) essentially takes on a life of its own. Note that depending on your net's initialization circuitry, you can have one or more active processes running around in it. The native state for a "raw" Nv Net at powerup is saturation -- here, there are half as many active processes as there are Nvs (alternate [[Nv]s are active at any given time). Depending on your application, this may be what you want, or you may want to use a process neutralizing circuit that reduces this mele to a single active process.