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Using the Indexer

The indexer is a floating X-Plane window that runs the OnSpeed M5 indexer firmware in-process and draws its framebuffer into a GL-textured quad. Same renderer as a real M5Stack — same chevrons, same donut, same percent-lift index bar, same fonts.

Show / hide

Two paths:

  • Plugins → Fly On Speed → Indexer: Show/Hide toggles the window.
  • The window honors X-Plane's standard floating-window chrome — drag by the titlebar to move, use the close button to dismiss.

The first time you show the indexer in a session, the plugin lazy-initializes SDL, the M5 firmware's setup(), the OpenGL texture, and the panel framebuffer. Expect a fraction of a second of latency on first show; subsequent shows are immediate.

Cycling modes

Two ways to change which of the five modes is on screen:

  • Click the MODE button at the bottom-center of the indexer window. Each click steps the mode forward; mode 4 wraps back to mode 0. The label updates to "MODE 0", "MODE 1", etc. Clicks on the indexer body itself, the titlebar, or anywhere outside the button are pass-through — they don't cycle the mode and don't steal focus from whatever you were doing.
  • Plugins → Fly On Speed → Indexer Mode N jumps directly to mode N. The window auto-shows if it isn't already visible.

The mode index is the same displayType the M5 firmware uses; the plugin's SetMode() writes the M5's global state directly so a plugin-side mode change behaves identically to a Button-B press on a physical M5.

Window appearance and behavior

Letterboxing

The indexer texture is 320×240 pixels (the M5Stack's native LCD resolution). When you drag the X-Plane window to a different shape, the texture stays at 4:3 aspect — it's centered with letterbox bars filling whatever extra space you've given it. Drag the window proportionally bigger and the texture scales together; drag wide or tall and the un-needed area shows the chrome bg.

This avoids the "stretched smooshed indexer" you'd otherwise get from non-4:3 windows.

Sticky position across launches

The indexer window remembers, per-aircraft, whether you had it visible, what mode it was on, where it was on the screen, what size, and whether it was in pop-out mode (own OS window, draggable to other monitors). All of that comes back the next time you load the same aircraft.

The restore happens during X-Plane's "Preparing world" phase — same timing as stock G1000 / X1000 windows snapping into their saved spots. Position-on-disk lives in Output/preferences/AOA-Tone-FlyOnSpeed-<aircraft>.prf alongside the audio settings. See Per-Aircraft Settings for the file's full schema.

Pop-out mode (multi-monitor)

The pop-out button on the X-Plane window's chrome (top-right) detaches the indexer into its own OS window — at which point you can drag it to a different monitor, snap it to a corner, etc., exactly like any other OS window.

The pop-out position persists separately from the floating position, so:

  • Drag the floating indexer to spot A, pop out, drag to monitor 2, un-pop → indexer returns to spot A.
  • Pop back out → returns to monitor 2 spot.
  • Quit X-Plane and relaunch in either mode → restores wherever you last had it.

The five modes

The same five modes the M5 firmware ships. For full descriptions of each mode (what every readout means, when to use it), see the external display modes section — the plugin runs the same C++ source.

Mode 0 — AOA + Numbers (Primary)

The default after first show. Vertical AOA indexer in the center, flanked by IAS, vertical-G, flap-position icon, percent-lift number, slip ball, and a G-onset rate tape on the right edge.

The indexer widget itself shows:

  • Top chevrons — getting-slow warning, yellow → red → flashing red as AOA crosses OnSpeedSlow, midpoint, and StallWarn.
  • Green donut (two horizontal arcs + center dot) — on-speed indicator, lit when AOA is in the OnSpeed band.
  • Bottom chevron — fast-but-safe (between LDmax and OnSpeedFast).
  • White index bar — current AOA on the percent-lift scale.

G-onset tape (right-edge yellow bar)

The yellow bar on the right edge is the rate of change of vertical G — how aggressively you're loading or unloading the airframe right now. Bar grows up from the center for positive onset (G load increasing — pulling into a turn or pull-up), grows down for negative onset (G unloading — pushing over, releasing back-pressure). Saturates at ±2 g/s. The center pip and ladder ticks give you a visual reference. The bar is computed by feeding the smoothed vertical-G signal through a 250 ms low-pass derivative — same filter the firmware feeds the wire from AHRS::Update.

Useful as an "am I loading the airframe smoothly?" cue: a steady long pull-up shows a small bar; a sudden yank shows a tall bar that dies back as the rate stabilizes.

Mode 1 — Attitude

Backup artificial horizon driven by X-Plane's pitch and roll. Pitch ladder, magenta flight-path marker (concentric rings + perpendicular wing bars), slip/skid ball at the bottom, white VSI tape on the right edge, IAS / pressure-altitude / vertical-G / percent-lift readouts in the corners.

VSI tape (right-edge white bar)

The white bar on the right edge is vertical speed — how fast you're climbing or descending. Bar grows up from the center for climbs, down for descents. Saturates at ±600 fpm: a steady 300 fpm descent fills half the bar; a 700 fpm climb pegs it to the top. The ±600 fpm range is tuned for the gentle-cruise band where small trends matter most — for larger excursions read the IAS / FPA numerics in the corners. The center pip and 20-pixel ladder ticks give a visual reference; the bar drops to the ladder color (zero) in level flight.

Mode 2 — Narrow AOA

Mode 0's indexer widget with all the numeric fields stripped away. Same chevrons, donut, and index bar; nothing else.

Mode 3 — Decel

Vertical "energy tape" gauge showing instantaneous airspeed deceleration in knots per second. Green band marks the stable-energy zone; red bands above and below flag rapid acceleration or deceleration. Useful for tuning approach energy.

Mode 4 — G History

Rolling 1-minute strip-chart of vertical G (the on-screen header reads G-LOAD [1 min]). Useful for spotting how hard you pulled in a maneuver after the fact.

What feeds the indexer

The plugin's IndexerWindow::Tick() callback runs every X-Plane flight loop. It reads X-Plane datarefs, builds a display-serial #1 frame in the same wire format the firmware emits, and feeds that frame into the M5's serial parser. The M5 renderer then runs its loop normally, drawing into the panel's framebuffer.

The percent-lift anchors (LDmax, OnSpeedFast, OnSpeedSlow, StallWarn) come from the four AOA setpoints in the audio control window — edit them there to recalibrate the indexer's chevron and donut gates. See Per-Aircraft Settings.