acquiring data from accelerometers
DESCRIPTION
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. - PowerPoint PPT PresentationTRANSCRIPT
DIGIKEY DKSB1002A3-axis accelerometer
Arduino Unomicrocontroller board
Parallax USB Oscilloscopemeasure voltage vs. time
Acquiring Data from Accelerometers
living with the lab
http://www.analog.com/static/imported-files/data_sheets/ADXL335.pdf
data sheet for accelerometer is available at . . .
• 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
Implementing a 3-axis Accelerometer: Hardware
xy
z
living with the lab
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
living with the lab
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);}
Implementing a 3-axis Accelerometer: Programming
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: _________
xy
z
living with the lab
Implementing a 3-axis Accelerometer: Angle Measurement
xy
z
1g (perceived vertical acceleration)
ax
x
x
+x
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
living with the lab
Measuring Output of Accelerometer with Parallax Scope
• 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 10k
5V
switch
trigger input