PY1CX / Cortex-M-FFT

Testing the FFT performance of Cortex-M microcontrollers on ST Nucleo boards

Cortex-M-FFT

Testing the FFT performance of Cortex-M microcontrollers on ST Nucleo boards

Results for arm_cfft_f32 function:

Core	32 points	512 points	1024 points	Performace gain in %
Cortex-M0	637	21	9	0%
Cortex-M3	2215	72	31	345%
Cortex-M4	133460	7113	2924	8445%
Cortex-M7 With Cache Disabled	160485	8038	3108	113%
Cortex-M7 With Cache Enabled	490595	24145	9807	307%

Yes, the difference between non-FPU and FPU-present cores blew my mind when I saw the results.

How to enable the cache on STM32H7 MCU:

Just enable the cache with the following code, before the function HAL_Init();

/* Enable I-Cache */
SCB_EnableICache();

/* Enable D-Cache */
SCB_EnableDCache();

How to link CMSIS-PACK (CMSIS-DSP) with projects generated from STM32CubeMX in Atollic TrueStudio.

With Atollic TrueStudio open: File -> C Project -> CMSIS C/C++ Project -> Atollic ARM Tools (use a mock-up name for this project). Next Next Select your microcontroller from the STMicroelectronics tab. Next Finish

With both projects open on your Atollic TrueStudio IDE, from the mock-up project you copy the following files to your STM32CubeMX project: RTE folder (projectname).rteconfig

On your real project to to the Properties (Project -> Properties)

C/C++ Build -> Settings

C Compiler -> Symbos add:

ARM_MATH_CM(your CM processor) _FPU_PRESENT= (0 or 1 depending on the microcontroller your're using)

C Linker - Libraries

Libraries ( Where you can see all pre-compiled libraries https://github.com/ARM-software/CMSIS/tree/master/CMSIS/Lib/GCC )

For M3 for example, add:

:libarm_cortexM3l_math.a

C Linker - Library Search Path:

Add: "${cmsis_pack_root}/ARM/CMSIS/5.3.0/CMSIS/Lib/GCC"

Remember, you NEED to install CMSIS Packs on Atollic! A tip to see if everything went smooth: Ctrl+Click the arm_math.h include line, if you done everything right you should open the file.