AnsweredAssumed Answered

Calibrating ADXL375

Question asked by ricardogomes on Jul 2, 2015
Latest reply on Jun 14, 2016 by Anthony.DeSimone

Hi, I have a ADXL375 accelerometer evaluation board which I've connected to an atmel board. I'm now able to configure the accelerometer as I want and read the acceleration. I've defined the Bandwidth = 800Hz and I'm reading X0 to Z1 at the same time. With the offset = 0 and Z at -1g and X and Y at 0g, I'm getting the following:

 

X0 = 64
X1 = 0
Y0 = 80
Y1 = 0
Z0 = 32
Z1 = 255

 

my sensitivity is 400/8192 = 0.048828125 g/LSB (~=49mg like the datasheet says).


So:

Xaccel = 64 * 0.049 = 3.136g
Yaccel = 80 * 0.049 = 3.92g
Zaccel = -224 * 0.049 = 10.976g

 

Well, like it says in the datasheet, 1g equals 20.5 LSB so it is not reasonable that I'm getting values >>>>>> 1g.

In the datasheet also says that the typical offset is 400mg ( offset ~= 0x02 for each axis because 1 LSB corresponds to 196 mg, right??) and if we look to the values I'm getting, it makes sense that my sensitivity should be 4.9mg so my values would be:

 

Xaccel = 0.3136

Yaccel = 0.392

(which would be ~0g with the 400mg of offset

and Zaccel = 1.0976g

 

Do you know what I'm doing wrong? Are the values that I'm getting normal or do they seem weird for you to?

 

Thanks in advance.

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