SmoothAxis

Stabilize noisy potentiometers, faders, and joysticks.

Stop your analog readings from flickering. SmoothAxis filters noise while keeping your controls responsive—no more fighting with magic numbers or watching your servo twitch.

Specify smoothing as a settle time in seconds. The filter adapts to your noise level automatically.

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Installation

Arduino Library Manager: Search for 'SmoothAxis' → Install

Or download manually and place in your Arduino libraries folder.

Quick Start

#include <SmoothAxis.h>

const int SENSOR_PIN = A0;
const int SENSOR_MAX = 1023;    // 10-bit ADC (use 4095 for ESP32)
const float SETTLE_TIME = 0.25; // Seconds to stabilize

SmoothAxis axis(SENSOR_MAX, SETTLE_TIME);

void setup() {
    Serial.begin(9600);
}

void loop() {
    axis.update(analogRead(SENSOR_PIN));

    if (axis.hasChanged()) {
        Serial.println(axis.read());  // Only prints on real movement
    }
}

That's it. No tuning required unless you want to.

Choosing Your Settle Time

Settle Time	Feel	Good For
0.05–0.15s	Snappy	Gaming, fast UI response
0.20–0.35s	Balanced	Most projects
0.50–1.0s	Smooth	Cinematic movement, lighting

Accuracy

Tested across clean and noisy conditions: ~1% timing error, zero false triggers.

Examples

Ready-to-run sketches in File → Examples → SmoothAxis:

Example	What It Shows
Simple	Basic potentiometer smoothing
Precision	Manual timing for variable loop rates
Plotter	Visualize raw vs. smoothed in Serial Plotter
Calibration	Fix pots that don't reach 0% or 100%

Features

• Easy tuning — set how fast SmoothAxis reacts to changes, in seconds

• Sticky zones — optional magnetic snap at 0% and 100% endpoints

• Dead zones — optionally clip unreliable sensor edges to clean values

• No false triggers — hasChanged() ignores jitter, catches real movement

• Frame-rate independent — works and feels the same on any board, at any processor speed

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Learn more here

Select Mode

AUTO Mode (Default)

The simplest option. SmoothAxis measures your loop timing automatically.

#include <SmoothAxis.h>

const int SENSOR_PIN = A0;
const int SENSOR_MAX = 1023;    // 10-bit ADC (use 4095 for ESP32)
const float SETTLE_TIME = 0.25; // Seconds to stabilize

// Default mode - timing handled internally via millis()
SmoothAxis axis(SENSOR_MAX, SETTLE_TIME);

void setup() {
    Serial.begin(9600);
}

void loop() {
    // Read sensor and update filter
    axis.update(analogRead(SENSOR_PIN));

    // Only fires on meaningful change, not noise
    if (axis.hasChanged()) {
        Serial.println(axis.read());
    }
}

LIVE Mode (Precision)

For fast chips or busy programs with varying workloads. You provide the exact time elapsed each frame, ensuring consistent smoothing even when loop speed fluctuates.

#include <SmoothAxis.h>

const int SENSOR_PIN = A0;
const int SENSOR_MAX = 1023;
const float SETTLE_TIME = 0.25;

// LIVE mode - you provide delta time manually
SmoothAxis axis(SENSOR_MAX, SETTLE_TIME, SmoothAxis::LIVE);

unsigned long lastMicros = 0;

void setup() {
    Serial.begin(9600);
    lastMicros = micros();
}

void loop() {
    // Calculate exact time since last update
    unsigned long now = micros();
    float deltaTime = (now - lastMicros) / 1000000.0;  // Convert to seconds
    lastMicros = now;

    // Pass delta time with update
    axis.update(analogRead(SENSOR_PIN), deltaTime);

    if (axis.hasChanged()) {
        Serial.println(axis.read());
    }
}

Utility & Diagnostics

Reading Values

uint16_t value = axis.read();        // Smoothed value [0..maxRaw]
float normalized = axis.readFloat(); // Smoothed value [0.0..1.0]
bool changed = axis.hasChanged();    // True once per meaningful change

Reset

axis.reset();           // Clear history, start at zero
axis.reset(currentRaw); // Clear history, start at specific position

Useful after sleep/wake or mode changes.

Diagnostics

float noise = axis.getNoiseLevel();  // Current noise estimate [0.0..1.0]
float thresh = axis.getThreshold();  // Active detection threshold [0.0..1.0]

Fine-Tuning: Dead Zones & Sticky Edges

Use fineTune() if your sensor has issues at the endpoints—for example, a potentiometer that only reads 15–1010 instead of 0–1023.

SmoothAxis axis(1023, 0.25);

void setup() {
    axis.fineTune(
        0.003,  // Sticky zone: magnetic snap at 0% and 100%
        0.02,   // Full off: treat bottom 2% as zero
        0.98    // Full on: treat top 2% as max
    );
}

Parameter	Default	Purpose
stickyZone	0.003	Hysteresis at endpoints (prevents dithering)
fullOff	0.0	Dead zone at low end
fullOn	1.0	Dead zone at high end

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More Information

This is the Arduino wrapper for the smooth_axis C library. Visit the main repository for algorithm details, test methodology, and platform-agnostic documentation.

Author

Jonatan Vider - LinkedIn - Viderspace@gmail.com