BMA456 & tilt sensing

[TEDKKKK]

Hello,

I'm reviewing IoT device with BMA456 and checking feasibility of tilt sensing solution.

I have a question about BMA456 tilt resolution for my project condition as below and pls give me your tips.

• static object (about 10kg) and very slow moving without acceleration influence .
• Needed tilt angle resoluton by cases : (1) 0.1 degrees (2) 0.5 degrees (3) 1.0 degrees 

of course I'll test it in real environment but I need your advice in advance.

Do BMA456 having 16bit (0.06mg/0.005deg) can detect  3 cases resolution (0.1/0.5/1.0degrees)? 

Thank you for your support in advance.

Thanks.

[FAE_CA1 · Accepted solution]

Hi,

Thanks for your inquiry.

BMA456 has noise density of 120ug/rt(Hz). If you choose 25Hz output data rate (ODR) for example, then the bandwidth will be 10.12Hz. Then the noise level (1-sigma) = noise density * sqrt(1.22 * BW), where 1.22 is the coefficient of the internal low pass filter = 120ug/rt(Hz) * sqrt(1.22 * 10.12Hz) = 0.42mg. Then 3-sigma noise level = 3 * 0.42mg = 1.26mg = 0.00126g with 99.7% confidence range. So the BMA456 tilt resolution = arcsine(0.00126g/1g) = 0.07degrees.

Therefore, BMA456 can detect 3 cases resolution (0.1/0.5/1.0degrees). If you choose 12.5Hz ODR with 5.06Hz bandwidth, then the tilt resolution will be even better.

Thanks.

Thanks.

[TEDKKKK · Accepted solution]

Thank you for your interest and explanation.