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l iving with the lab. Acquiring Data from Accelerometers. Arduino Uno microcontroller board. DIGIKEY DKSB1002A 3-axis accelerometer. Parallax USB Oscilloscope m easure voltage vs. time. data sheet for accelerometer is available at.
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living with the lab Acquiring Data from Accelerometers Arduino Uno microcontroller board DIGIKEY DKSB1002A 3-axis accelerometer Parallax USB Oscilloscope measure voltage vs. time data sheet for accelerometer is available at . . . http://www.analog.com/static/imported-files/data_sheets/ADXL335.pdf
living with the lab Implementing a 3-axis Accelerometer: Hardware • DKSB1002A is a prototyping board • $20 from www.digikey.com • Screw holes for mounting board onto “object of interest” • Board is ~ 20mm square • ADXL3355 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 z x y
living with the lab Implementing a 3-axis Accelerometer: Wiring to Arduino • COM - ground • VSS - power (we will provide 5V) • X - acceleration in x-direction • Y - acceleration in y-direction • Z - acceleration in z-direction
living with the lab Implementing a 3-axis Accelerometer: Programming void setup() { Serial.begin(9600); } void loop() { int xaccel = analogRead(0); int yaccel = analogRead(1); int zaccel = analogRead(2); Serial.print(xaccel); Serial.print(" "); Serial.print(yaccel); Serial.print(" "); Serial.println(zaccel); }
living with the lab Implementing a 3-axis Accelerometer: Analysis of Output • Output from accelerometer will vary from 0 to 5 V • Output when +x points upward: __________ • Output when +x points downward: __________ • Difference: _______ • Change in acceleration = 2g • Change in accelerometer per g: ___________ • Output when accelerometer is flat: _________ z x y
+x qx ax qx 1g (perceived vertical acceleration) living with the lab Implementing a 3-axis Accelerometer: Angle Measurement z x y θx = asin(ax/g) • Expected output of Arduino when accelerometer is flat: _________ • Expected output of Arduino when accelerometer is at 45 degrees? ________ • If the Arduino output is 350, then what is the angle? ___________
living with the lab Measuring Output of Accelerometer with Parallax Scope 5V switch trigger input 10kW • Attach channel 1 leads between x-acceleration signal and ground • Oscilloscope plots voltage vs. time • Export data to a file to acquire voltage (or acceleration) vs. time data • Example of how a switch circuit is used to trigger data acquisition