fft latency problem in nrf52

[bigzero]

i am working using NRF52, s132, sdk11, freertos.

for fft , i used "arm_rfft_fast_f32(...)" in cmsis-dsp library.

and i inserted a fpu interrupt.

NVIC_SetPriority(FPU_IRQn, APP_IRQ_PRIORITY_LOW);
NVIC_ClearPendingIRQ(FPU_IRQn);
NVIC_EnableIRQ(FPU_IRQn);

void FPU_IRQHandler(void)
{
     uint32_t *fpscr = (uint32_t *)(FPU->FPCAR+0x40);
     (void)__get_FPSCR();
      NVIC_ClearPendingIRQ(FPU_IRQn);

     *fpscr = *fpscr & ~(FPU_EXCEPTION_MASK);
}

if i enable a FPU_IRQ, the fft latency is very long.

if i disalbe a FPU_IRQ, the fft latency is very fast. but I can't enter to sleep.

and system is very unstable.

i would like to know the best setting for a fft performance in freertos+s132+nrf52.

thank you

[RK]

FPSCR is stacked as part of the interrupt handler, so masking it doesn't help you as it's restored again. You need to find the value on the stack and adjust that so it's popped back into the FPSCR.