For the MAXREFDES101, MAXREFDES220 and other boards used used with a MAX32664 sensor hub, the default sampling rate of a SmartSensor is 25hz for all sensors and algorithms. Default fifo threshold is 15. Smart sensor reports data ready by pulling the mfio pin low at every 15/25 seconds. Fifo is read in burst mode; ie 15 samples in a single transaction. So, the default rate for sampling the fifo buffer is 25/15 Hz.
If one tries to read the fifo when mfio pin is high or data ready is not reported by the smart sensor, one sees unexpected results.
In order to sample fifo at higher rates, the sampling rate of the algorithm/algorithms and sampling rate of the sensor must be adjusted to the same sampling rate. Maximum value is 100Hz. So one can achieve 100/(fifo threshold) hz for fifo buffer sampling.