Hello everyone,

I'm looking into measuring the vibrations of a large telescope structure. My idea was to use an ADXL355 evaluation board, connect it to a microcontroller (Arduino) and have the data written to SD card. However I want to clarify/confirm a few things before I continue:

1.Resolution: I'm expecting to measure a peak acceleration in the order of 10mg with a frequency in the order of 1Hz. If i understood it correctly, the resolution is limited by noise which in turn is related to the bandwidth, so I probably want to limit my bandwidth in order to achieve higher sensitivity (from my calculation, limiting the bandwidth to 100Hz, with the given noise density of the ADXL355 results in a total noise of 0.3mg).

My question is: Is the bandwidth limit determined by an analogous low pass filter, or by some sort of digital filtering/setting? Also, how can this limit be modified?

2.Interfacing: How "easy" is it to interface the ADXL355 with a microcontroller (eg. via SPI) for someone that is new to the topic?

• QUESTION

1.Resolution: I'm expecting to measure a peak acceleration in the order of 10mg with a frequency in the order of 1Hz. If i understood it correctly, the resolution is limited by noise which in turn is related to the bandwidth, so I probably want to limit my bandwidth in order to achieve higher sensitivity (from my calculation, limiting the bandwidth to 100Hz, with the given noise density of the ADXL355 results in a total noise of 0.3mg).

My question is: Is the bandwidth limit determined by an analogous low pass filter, or by some sort of digital filtering/setting? Also, how can this limit be modified?

The ADXL355 contains both analog (internal) and digital filters.  The Filter register (see page 37 of the ADXL355 datasheet) provides a user-control for the digital filter.  Table 43 provides some details on the filter options that are available through the digital filter that is in the ADXL355's (internal) signal chain.

• QUESTION

2.Interfacing: How "easy" is it to interface the ADXL355 with a microcontroller (eg. via SPI) for someone that is new to the topic?