adxl320 accelerometer resolution

Forum 2005-2010 (read only) Hardware Interfacing
1

Hello

Im trying out my new adxl320 +-5g with my Arduino UNO and the onboard adc.

When tilting and testing the device in 180 degrees I get accelerometer values ranging from + - 75. (440-570) is this normal?

here is another example adxl3xx 2g: http://arduino.cc/en/Tutorial/ADXL3xx where the range become greater, around +- 150 in acc. value.

there is 2g accelerometers you can buy, will this increase the range and make it more sensitive ?

if so, how come higher G's are more expensive when the range is smaller ?

2

The ADXL320 output is ratiometric, so the output sensitivity (or scale factor) varies proportionally to supply voltage. At VS = 5 V, the output sensitivity is typically 312 mV/g.

One count of analogRead() is about 4.9 mV so 75 counts is 'bout 366 mV or 1.2 g.

AD sells these to a sensitivity of 1000 mV/g, look for Precision ±1.7 g Single-/Dual-Axis
i MEMS® Accelerometer ADXL103/ADXL203.