Using Const Variables Makes Current Goes Up

[Emile]

Hi!

I'm developping a battery powered product, so the power consumption is important. I need to multiple an array point by point with an array (hamming window) that I store in the flash as "const":

const float hamming[] = {
0.08000000000000002,
0.08000054147657765,
0.08000216590503589,
0.08000487328155026,
0.08000866359974718,
0.080013536850703,
0.0800194930229452,
0.08002653210245131,

...

There is the multplication:

void hamming_windowing(int16_t *signal, uint32_t size)
{
   int i = 0;
   for (i = 0 ; i < size/2; i++)
   {
       signal[i*2] = signal[i*2] * hamming[i] ;
   }
}

But when I multiple an array with this const array, the power consumption goes up to 7 mA. I'm able to achieve 15 uA without this operation. I suspect that something is going on with the flash. What can be the issue?

Thank you!

[Kenneth]

Check out:
https://infocenter.nordicsemi.com/topic/errata_nRF52832_Rev2/ERR/nRF52832/Rev2/latest/anomaly_832_87.html#anomaly_832_87

If you are using the softdevice you should always use sd_app_evt_wait(), not __WFE() directly.

Kenneth

[Emile]

Well the power consumption seemed to be due to the fact that my const array was stored as float. I changed it to double and the problem seems to be gone. What could explain this rise in power consumption? Was it because other section of the CPU was enabled for this operation when the array was stored as a float?

Thank you!