DIGIKEY DKSB1002A Evaluation Board3-axis accelerometer

Arduino Unomicrocontroller board

Acquiring Data from anADXL335 Accelerometer

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• DKSB1002A is a prototyping board purchased for $20 from Digikey • Screw holes for mounting board onto “object of interest”• Board is ~ 20mm square• ADXL335 3-axis accelerometer chip

• 3-axis• ±3g

• COM - ground• VSS - power (we will provide 5V)• X - acceleration in x-direction• Y - acceleration in y-

direction• Z - acceleration in z-direction

DKSB1002A Evaluation Board and ADXL335 Accelerometer

xy

z

this small chip is the ADXL335 accelerometer(this is an older model . . . they are even smaller now)

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the DKSB1002A is a board used to evaluate the accelerometer; if you were putting an accelerometer in a device like a cell phone, you would only use the ADXL335 chip (and maybe some capacitors)

COM - groundVSS - power (we will provide 5V)X - acceleration in x-directionY - acceleration in y-directionZ - acceleration in z-direction

Implementing a 3-axis Accelerometer: Wiring to Arduino

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

void loop(){ int xaccel = analogRead(0); int yaccel = analogRead(1); int zaccel = analogRead(2); unsigned long timevar = millis(); Serial.print(timevar); Serial.print(" "); Serial.print(xaccel); Serial.print(" "); Serial.print(yaccel); Serial.print(" "); Serial.println(zaccel);}

Programming

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associates a time witheach set of accelerations

Calibration

xy

z

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Angle Measurement

xy

z

1g (perceived vertical acceleration)

ax

x

x

+x

θx = asin(ax/g)

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Example Application

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

void loop(){ int xaccel = analogRead(0); int freq = 1500+xaccel*2; tone(7,freq);

Serial.print(xaccel); Serial.print(" "); Serial.println(freq);}

The piezospeaker below outputs a frequency that varies with the acceleration in the x-direction. The equation for computing the frequency is chosen so that the device makes an audible noise that varies when rotating or shaking the device.