Overview

The ADXL335 is a classic 3-axis analog MEMS accelerometer manufactured by Analog Devices. Housed in a compact $4 \times 4\text{ mm}$ 16-lead LFCSP package, it measures dynamic acceleration (motion, vibration, shock) and static acceleration (gravity tilt) across a $\pm 3g$ full-scale range.

Unlike digital accelerometers (such as the ADXL345 or MPU6050) that output $I^2C$ or SPI registers, the ADXL335 features pure ratiometric analog voltage outputs for X, Y, and Z axes. Each axis output voltage is centered at $\frac{V_{CC}}{2}$ ($1.65\text{V}$ at 3.3V supply) and shifts by $300\text{ mV/g}$. It is widely used in simple tilt switches, RC model leveling, and analog microcontroller projects.

Quick reference

Pinout

Common 5-pin GY-61 breakout board header:

Specifications

Analog Voltage Conversion Formula

Because outputs are ratiometric (proportional to supply voltage $V_{DD}$), acceleration in $g$-force is calculated as:

$\text{Acceleration } (g) = \frac{V_{out} - V_{zero\_g}}{\text{Sensitivity}} = \frac{V_{out} - (V_{DD} / 2)}{0.300\text{ V/g}}$

For a 10-bit ADC reading on Arduino (3.3V reference $V_{REF} = 3.3\text{V}$):

$g_x = \frac{\left( ADC_x - 512 \right) \times 3.3}{1023 \times 0.300}$

Wiring

Example

const int xPin = A0;
const int yPin = A1;
const int zPin = A2;

// Zero-g ADC baselines (calibrated per sensor)
int zeroG_X = 512;
int zeroG_Y = 512;
int zeroG_Z = 512;

void setup() {
  Serial.begin(9600);
  // Set ADC reference to 3.3V AREF pin on 5V Arduino Uno
  analogReference(EXTERNAL);
}

void loop() {
  int rawX = analogRead(xPin);
  int rawY = analogRead(yPin);
  int rawZ = analogRead(zPin);

  // 3.3V / 1024 = 3.22 mV per count; 300 mV/g sensitivity -> 0.0107 g per count
  float gx = (rawX - zeroG_X) * 0.0107;
  float gy = (rawY - zeroG_Y) * 0.0107;
  float gz = (rawZ - zeroG_Z) * 0.0107;

  Serial.print("X: "); Serial.print(gx); Serial.print(" g\t");
  Serial.print("Y: "); Serial.print(gy); Serial.print(" g\t");
  Serial.print("Z: "); Serial.print(gz); Serial.println(" g");

  delay(200);
}

Common mistakes

• Not setting analogReference(EXTERNAL) on 5V Arduino: Reading a 3.3V analog sensor using a default 5.0V ADC reference reduces measurement resolution and distorts $g$-force math.
• Forgetting per-sensor zero-$g$ offset calibration: Manufacturing tolerances introduce $\pm 150\text{ mV}$ offset shifts. Place the sensor flat on a level surface and calibrate zero-$g$ ADC constants for X and Y, and $+1g$ for Z.

Notes

• ADXL335 vs ADXL345: ADXL335 is 3-axis analog ($\pm 3g$ max); ADXL345 is 13-bit digital $I^2C$/SPI ($\pm 16g$ max).