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I'm open sourcing Pickaxes, a C library for calibrating and shaping analog sticks and triggers on 32-bit microcontrollers, designed for people building portables and custom controllers. github.com/loopj/pickaxes

Calibration comes first. Pickaxes runs a calibration session on the firmware that captures rest position, min and max travel, and orientation. Release the stick, push it in each direction, rotate it around the rim. Drive it from a homebrew app or a button combo on the device.

Shaping comes second, and is where the feel comes from. Inner and outer deadzones in axial or radial shapes, gamma response curves, and circular, square, or octagonal virtual gates, all in one struct you can change at runtime without recalibrating.

Calibration and shaping get combined into a small precomputed transform at boot (or whenever they change). The poll loop just calls "apply", a handful of integer operations with no FPU required. Plain C99, no dependencies, no allocation.