ADXL335 - what's the value of g?
Re: ADXL335 - what's the value of g?
Re: ADXL335 - what's the value of g?
Re: ADXL335 - what's the value of g?
dintymoore wrote:If I brought the ADXL to the moon and dropped it, would it show an acceleration of g or less than g?
Re: ADXL335 - what's the value of g?
Re: ADXL335 - what's the value of g?
Re: ADXL335 - what's the value of g?
uoip wrote:The highest value in that table is 9.819 in Helsinki, and the lowest value is 9.781 in Jakarta and Calcutta. Those values vary by 0.038, which is about 0.39%
Looking at the ADXL335's data sheet tables of sensitivity, there's somewhere around a 2% variation among samples. In other words, sample-to-sample variation in the chip is more than five times greater than the variation from the highest to lowest local value of gravitational acceleration in populated cities.
Re: ADXL335 - what's the value of g?
I'm pretty sure this indicates that the accuracy of the output voltage is +/- 10%:
Re: ADXL335 - what's the value of g?
Some_call_me_Tim wrote:However, we can easily calibrate out for this variation by comparing it to the local gravity.
Re: ADXL335 - what's the value of g?
Each of those sources of error have to be tackled in different ways. Noise can be averaged out. Temperature drift can be eliminated by regulating the temperature. The output is ratiometric so you better reference the same input voltage for the ADC. I did forget to mention zero offset . :oops:Ideally, yes. In practice...test your assumptions. That only works if:
* The deviation is fixed and does not include noise / drift / error / etc.
* The deviation is constant deviation, not a variation in response
* You check each axis individually (a three-axis sensor is generally three independent one-axis sensors on Si)
That should be if accuracy is important to you. Accuracy is how close something is to the correct value. Precision is how much error is in the measurement. For example, x= 2+2 the answer x= 4 is accurate, while x=3.987654321 is very precise, it isn't very accurate.If precision is important to you, characterize your sensor.
Re: ADXL335 - what's the value of g?
Some_call_me_Tim wrote:That should be if accuracy is important to you.