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Using CCM memory

Question asked by popiol on Jul 3, 2012
Latest reply on Dec 15, 2013 by Bellons

When I was testing DSP efficiency i tried compare how fast is FFT from data from internal SRAM and CCM.
The code looks like this:

 

int16_t

 

tab[2048]__attribute__ ((section(".ccm")));

 

 

...

 

GPIO_Pin_high();

 

 

arm_cfft_radix4_q15(&S, tab);

 

 

arm_cmplx_mag_squared_q15(tab, Output, fftSize);

GPIO_Pin_low();

When the tab was in internal SRAM this code was execute faster. I don't know why. Isn't it shoudl works faster? CCM is memory only for core and it should be the fastest memory. If it's not as fast then what's the reason of using it?

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