Acquiring Data from Accelerometers living with the lab Acquiring Data from Accelerometers DIGIKEY DKSB1002A 3-axis accelerometer Parallax USB Oscilloscope measure voltage vs. time Arduino Uno microcontroller board data sheet for accelerometer is available at . . . http://www.analog.com/static/imported-files/data_sheets/ADXL335.pdf

Implementing a 3-axis Accelerometer: Hardware 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

Implementing a 3-axis Accelerometer: Wiring to Arduino 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

Implementing a 3-axis Accelerometer: Programming 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.println(zaccel);

Implementing a 3-axis Accelerometer: Analysis of Output 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: _________ x y z

Implementing a 3-axis Accelerometer: Angle Measurement living with the lab Implementing a 3-axis Accelerometer: Angle Measurement 1g (perceived vertical acceleration) ax qx +x θx = asin(ax/g) z x y 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? ___________

Measuring Output of Accelerometer with Parallax Scope living with the lab Measuring Output of Accelerometer with Parallax Scope 10kW 5V switch trigger input 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