sampling frequency for adxl345?

the delay i used for adxl345 for measuring acceleration is 100 milliseconds and the data rate of adxl345 during measurement is 100hz, then what is the sampling frequency should i use for doing fft analysis of acceleration data?

[Mathieu NOE]

hello

at the best , the fft sampling rate is the same as the signal sampling rate.

you could of course do a signal decimation before the fft if you want something more focused on the low frequency range (in that case your fft rate is k times lower than the signal sampling rate , if k is your decimation factor)