Motion Sensing

The Cyber Fidget has an accelerometer that measures tilt and acceleration. Use it for tilt-controlled games, gesture detection, or any app that reacts to how the device is held.

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What is this?

An accelerometer measures acceleration (including gravity) along three axes. When the device is still, it mostly senses which way is "down" — so you can infer tilt.

Like the tilt sensor in your phone

When you rotate your phone and the screen flips, that's the accelerometer. The Cyber Fidget uses the same idea: tilt the device and read X, Y, Z values to control your app.

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Three axes

Axis	Direction	Typical use
X	Left–right tilt	Paddle movement, horizontal control
Y	Forward–backward tilt	Depth, forward/back
Z	Up–down	Vertical, "is it flat?"

When the device is flat (screen up), Z is near 1g (≈1000) and X, Y are near 0. Tilting changes the distribution. Values are in raw units (roughly ±1000–±1100 for 1g).

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Global variables

The HAL updates these every 50 ms:

Variable	Type	Description
accelX	float	Left–right acceleration
accelY	float	Forward–backward acceleration
accelZ	float	Up–down acceleration

Include HAL.h (or globals.h which includes it) to use them.

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Code example: tilt-controlled paddle

#include "HAL.h"
#include "globals.h"

float paddleX = 64.0f;  // Center of screen
const float paddleSpeed = 2.0f;

void update() {
    // Move paddle based on X tilt (negative factor for natural feel)
    paddleX += accelX * paddleSpeed * -0.01f;

    // Clamp to screen edges
    if (paddleX < 0) paddleX = 0;
    if (paddleX > 128) paddleX = 128;

    display.clear();
    display.fillRect((int)paddleX - 20, 56, 40, 4);  // Draw paddle
    display.display();
}

Sign and scale

The sign of accelX/accelY depends on orientation. Multiply by a small factor (e.g. 0.01) and tweak until movement feels right. You may need to negate for intuitive control.

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Code example: tilt-to-color

// Map X, Y, Z to RGB for a simple visual
uint8_t r = map(accelX, -1030, 1030, 0, 255);
uint8_t g = map(accelY, -1030, 1030, 0, 255);
uint8_t b = map(accelZ, -1030, 1030, 0, 255);
HAL::setRgbLed(pixel_Front_Top, r, g, b, 0);
updateStrip();

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Framework details

LIS2DH12

The accelerometer is an ST LIS2DH12, a 3-axis digital accelerometer. The firmware uses the SparkFun LIS2DH12 Arduino library for I2C communication.

TASK_50MS update rate

The HAL reads the accelerometer every 50 ms (20 Hz) in its TASK_50MS block. accelX, accelY, and accelZ are updated from s_accel.getX(), getY(), and getZ(). For most tilt-based apps, 20 Hz is sufficient; for fast gestures you may want higher-rate polling if the hardware supports it.

Accessing the sensor directly

For advanced use, get the sensor reference:

SPARKFUN_LIS2DH12& accel = HAL::accelerometer();
// Use accel for raw config, interrupts, etc.