Currently, Maxim has not written any Fast Fourier Transform (FFT) math software libraries for the MAX32625. That said, ARM has written optimized FFT functions in their CMSIS-DSP software library for the Cortex M3 and M4 cores. Maxim has not characterized how well this code library compiles or runs on the MAX326XX devices, but more information is available from ARM here: https://developer.arm.com/technologies/dsp/dsp-for-cortex-m . Also, see Keil's documentation page for the CMSIS DSP Software Library here: http://www.keil.com/pack/doc/CMSIS/DSP/html/index.html . Keep in mind that FFT software usually runs best on microcontrollers with floating point units. ARM designates their cores containing floating point units with an "F", such as "Cortex-M4F". Information about writing custom FFT software can be found here: http://edp.org/work/Construction.pdf . Also, for non-floating-point microprocessors, check GitHub.com for integer-based FFT libraries.