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Has anybody implemented CMSIS FFT library Successfully?

Question asked by Amit Kumar on Jun 26, 2014
Latest reply on Jun 4, 2020 by Mark Butcher


I want to use arm_cfft_radix4_init_q15() and arm_cfft_radix4_q15() function from CMSIS 3.2 library . I am unable to find any good resources or any examples. I have looked in the documents provided by ARM i.e CMSIS-DSP: Complex FFT Functions but I didn't find it useful. What are the inputs given to these functions I am still not clear with it. I tried writing the codes but it didn't worked

this is how I am calling the functions,


arm_cfft_radix4_init_q15(&arm_cfft_sR_q15_len256, 256, 0, 1);          // For init

arm_cfft_radix4_q15(&arm_cfft_sR_q15_len256, az);                      // For transformation where,

arm_cfft_radix4_instance_q15 arm_cfft_sR_q15_len256 = {256, 0, 1, twiddleCoef_256, armBitRevIndexTable256, 4U, 4U};


  and az[512] is an array where the data is stored. Just for testing 

float32_t az[512] = {1.2 ,0.0

                             1.3, 0.0



                              1.2, 0.0};

my programs hangs and I am not able to print the o/p. I am using Codewrrior 10.5 and want to implement this on FRDM-K20D50M. I posted the query in ARM's community also but I didn't get any response which makes me think if anybody is actually using this library. Please look into the matter.


Kind Regards

Amit Kumar