Waveform Input

Overview

A Waveform Input generates a timed value — a waveform — in response to the edges of another input. When the observed input switches on or off, it plays back a sequence of (time, value) points you define. Typical uses are clutch-by-wire engage on button press and release on button release, blinker / hazard lights, and simple test signals. It watches an input you already configured and produces a value from it.

Prerequisites & hardware

  • A source input to observe — usually a button or switch (for example a Digital Input). Create it first and note its identifier.
  • The observed input is treated as digital: a value < 512 is LOW, a value ≥ 512 is HIGH.
  • A LOW → HIGH transition fires the RISE trigger.
  • A HIGH → LOW transition fires the FALL trigger.
  • At startup no transition is detected, so the first trigger can occur no earlier than the second cycle.

Add it in the app

  1. Add a new input and choose Waveform Input as the type.
  2. Set the Observed input to the source you want to watch.
  3. Give it a clear alias (e.g. Clutch Command).
  4. Define the Rise waveform and Fall waveform as lists of (time, value) points.
  5. Set the idle values and the repeat / minimum repeats behaviour.

Settings reference

Setting Meaning Unit Range / values Notes
Observed input The input whose edges trigger the waveforms — int32 (input id) Read as digital: < 512 LOW, ≥ 512 HIGH.
Rise waveform Points played on a LOW → HIGH edge (ms, value) pairs list of sint32 times + sint32 values Time stamps in ms; output value at each point. An empty list outputs the idle value.
Fall waveform Points played on a HIGH → LOW edge (ms, value) pairs list of sint32 times + sint32 values As above, for the falling edge.
Rise repeat Loop the rise waveform — on / off Off: play once, then hold the idle value (or stop early if a new trigger arrives and minimum repeats > 0). On: when the timer passes the last point, reset and replay from the start.
Fall repeat Loop the fall waveform — on / off As above, for the fall waveform.
Rise minimum repeats Full plays before a new trigger can interrupt the rise waveform plays int (0, 1, n) 0 = interruptible as soon as the next trigger is seen; 1 = play at least once fully; n = at least n times. Ignored when Rise repeat is off.
Fall minimum repeats Full plays before a new trigger can interrupt the fall waveform plays int (0, 1, n) As above, for the fall waveform.
Idle value (LOW) Output when no waveform is playing and the observed input is LOW value sint32 Held between waveforms.
Idle value (HIGH) Output when no waveform is playing and the observed input is HIGH value sint32 The input picks LOW or HIGH idle from the observed input's current state.

How a waveform is described

Each waveform is a list of (time, value) points. After a trigger, a timer starts at 0 ms and the input outputs the value scheduled for the elapsed time, linearly interpolating between points to give a smooth ramp:

value
 1000 |          ______
      |         /
    0 |________/
      +--------+----+----> time (ms)
      0       200  300
   points: (0,0) (200,1000) (300,1000)   -> interpolated between points

When the timer passes the last point, the input either holds the idle value (repeat off) or resets to 0 ms and plays again (repeat on).

Common settings

Waveform Input also uses the shared setting — alias. See Common IO Settings.

Example — clutch engage on press, ramped release on release

Watch a clutch button (a Digital Input) and drive a clutch command from 0 (open) to 1000 (closed).

  1. Type Waveform Input, alias Clutch Command, Observed input = the clutch button.
  2. Rise waveform (button pressed → engage quickly): (0 ms, 0) → (200 ms, 1000) — ramps up over 200 ms.
  3. Fall waveform (button released → ramp out gently): (0 ms, 1000) → (600 ms, 0) — ramps down over 600 ms.
  4. Rise repeat off, Fall repeat off — each plays once, then holds idle.
  5. Idle value (LOW) 0, Idle value (HIGH) 1000 — so once engaged it stays closed and once released it stays open.

For a hazard light instead: put a square pulse in the Rise waveform and turn Rise repeat on so it blinks continuously until the next trigger.

Troubleshooting

  • Nothing happens on the first press: at startup no edge exists; the first trigger comes no earlier than the second cycle. Toggle the input once.
  • Waveform never stops / keeps looping: repeat is on. Turn it off for a one-shot, or set minimum repeats so the next trigger can interrupt it.
  • A new press is ignored mid-play: minimum repeats is too high — lower it (or use 0) so the next trigger can interrupt.
  • Output sits at the wrong level between presses: check Idle value (LOW/HIGH).
  • Ramp too fast or too slow: adjust the point timestamps — the output interpolates linearly between consecutive points.
  • Triggers fire on the wrong edge: LOW/HIGH is split at 512 — make sure the observed input crosses that threshold.