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ODR and I2C communication speed in ADXL313

Question asked by tao2020 on Oct 9, 2014
Latest reply on Nov 9, 2014 by tao2020

Hello,

 

I have two questions about ADXL313.

1) According to datasheet of ADXL345/6 and 375, the relationship of the output data rate (ODR) and SPI communication speed is described in I2C mode page. (Following description)

 

" Due to communication speed limitations, the maximum output data rate when using 400 kHz I2C is 800 Hz and scales linearly with a change in the I2C communication speed. For example, using I2C at 100 kHz would limit the maximum ODR to 200 Hz."

 

In case of I2C in AXL313, the relationship of ODR and communication speed is not described in datasheet.

So, I think that it's same as ADXL345/6's (above condition).Our understanding is correct?

 

2) The relationship of the output data rate (ODR) and additional noise is described in ADXL313 SPI mode page (page10).

(Following description)

 

"Operation at an output data rate below the recommended minimum may result in undesirable effects on the acceleration data, including missing samples or additional noise."

 

About "additional noise",

Is there a possibility that noise will increase under the effect of the SPI/I2C communication rate?

I think that the noise will be increased by the relationship of the noise from the sensor and the ODR.

(For example, the internal LPF will be through at 1600/3200Hz ODR. It will be affected by the noise from the sensor more.)

Our understanding is correct?

 

Thanks.

Tao

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