Editing Guide to circuits (section)

== Fundamentals, Part III: Pulses ==

As mentioned earlier, '''pulses''' are what tells a machine to operate. They're the only way to make it ''do'' anything, because even with data values, it can't use them unless it hears something telling it to. There are two types of pulses, PULSE_IN and PULSE_OUT.

PULSE_IN pulses are "listeners." When they receive a command, they will run whatever function they're linked to. For instance, the "light" component has a PULSE_IN called "toggle light." When that toggle light receives a command, it will toggle the light component on or off. ''However,'' PULSE_IN components '''can''' link to other PULSE_IN components and work together with them. The "button" component uses a PULSE_IN called "on pressed" to communicate its pulses.

PULSE_OUT pulses are "speakers." They do not receive commands directly, but will ''output'' commands when certain actions transpire. For instance, the "reagent pump" component has a PULSE_OUT called "on transfer." Whenever the reagent pump successfully transfers reagents, it will send a command from "on transfer", and any PULSE_INs linked to that will receive a command. PULSE_OUT pins ''cannot'' be linked to other PULSE_OUT pins.

Understanding pulse links is essential to making circuits work. As an example, the button component's "on pressed" can be linked to the light component's "toggle light" using a circuit wirer. As long as the assembly has power, this will cause the light to toggle on and off when the button is pressed by using the assembly in your hand. You can also link multiple pulses together; even when it's linked to "toggle light", you can also put that "on pressed" onto a beeper circuit's "play sound" to make it play its sound with the value it's been assigned. This will make pressing the button toggle the light ''and'' play a sound.

=== A Note on "push ref" ===

Some circuits, especially those with an output pin that references itself, have a PULSE_IN pin called "push ref." When pulsed, this pin will cause any other components this part is linked to via that reference to actually obtain the reference for it. However, if you ''don't'' do this, then it will refer to the self-reference of the component as null, thus making it impossible to work. For this reason, "push ref" should be pulsed '''''exactly once''''' in order to synchronize it with other components.

The easiest way to do this is with a "starter" component, in the Power - Passive section. This component will pulse out a single time whenever the machine gains power. Linking the starter's "pulse out" to any "push ref" pins in your circuit is essential to getting them to work. You can also assign them in other ways, but note that pulsing "push ref" while the machine is running ''will'' cause it to malfunction and not work with no clear indicator.