The transform point size can be set through the NFFT field in the Configuration channel if the run time configurable transform length option is selected. Valid settings and the corresponding transform sizes are provided in Table: Valid NFFT Settings . If the NFFT value entered is too large, the core sets itself to the largest available point size (selected in the IDE). If the value is too small, the core sets itself to the smallest available point size: 64 for the Radix-4 Burst I/O architecture and 8 for the other architectures.