Saturday, April 21, 2012

Tinkering Accelerometer + Gyroscope AKA IMU (Part 1)

Its been some time since I fiddle with anything interesting...

The amplifier chassis is fun but just couldn't drag myself to build it as it doesn't arouse any sense of achievement since it never do anything at all...

Dug out this dust covered 5DOF IMU from my hoarder's corner...

I bought this for a song while roaming mindlessly in the deep internet space sometime ago...

Doing something with this will surely beats any amplifier projects.

 
Let me introduce you to this little gem.
It is an analogue output 5DOF(Degree of Freedom) IMU (Inertia Moment Unit) board consisting of 3 axis accelerometer ADXL335 chip by  Analog Devices and  2 axis gyroscope chip IDG500 by InvenSense.

This will save me from soldering 2 multi-legged SMT chip which are about the size of my nostril hair. 

SPECIFICATIONS

Accelerometer
AnalogDevices 
ADXL335

Axis
X, Y, Z
Measuring Range
±3.6g
Non-Linearity
±0.3%
Vcc
3.3V
Sensitivity at Xout, Yout, Zout
270~330mV/g,
typically 300mV/g
Zero g Bias Level (Ratiometric)
0g Voltage at Xout, Yout


0g Voltage at Zout


1.35~1.65V,
typically 1.5V

1.2~1.8V,
typically 1.8V
Frequency Response
Bandwidth Xout, Yout
Bandwidth Zout

1600Hz
550Hz

Gyrometer
InvenSense 
IDG500

Axis
X, Y

Full-Scale Range
Sensitivity
X-OUT & Y-OUT

X4.5Out & Y4.5Out

X-OUT & Y-OUT

X4.5Out & Y4.5Out
±500°/s


±110°/s


2.0mV/°/s


9.1mV/°/s
Frequency Response
140 Hz

Zero-Rate Output
Static (Bias)
Factory set
1.35V

Vcc
3.3V



IMU SHIELD

Even though it is a breakout board, This thing is still tiny my my standard! 
To save my sanity & eyesight, I drawn up a PCB as shield for Arduino.

IMU Arduino Shield
By fiddling with the jumper pin, I can choose which ever accelerometer axis Xout,Yout or Zout to A0 pin & Gyro's X-OUT, Y-OUT, Z-OUT, X4.5Out or Y4.5Out to A1 pin just
Others stuff the PCB design to do, 
1) tied up the Vcc to the Arduino ARef pin.
2) add pads & holes so that there is an option to solder or using pin plug to get to the Arduino pinouts.

Word budget is up for this article. In the part 2 of this series of article, I'll dive into reading the IMU which will involve some maths, some coding & some simple point to point wiring.

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