inv_sqrt() function will increases power

RE: inv_sqrt() function will increases power

dejans — Tue, 31 May 2022 12:05:47 GMT

Hi,

I provided a link for you previously. Here it is again - workaround.

Best regards,
Dejan

RE: inv_sqrt() function will increases power

eview — Tue, 31 May 2022 11:43:02 GMT

what's it mentioned? do you show the code?

RE: inv_sqrt() function will increases power

dejans — Tue, 31 May 2022 11:05:56 GMT

Hi,

You could try applying mentioned workaround before going into the sleep mode.

Best regards,
Dejan

RE: inv_sqrt() function will increases power

eview — Tue, 31 May 2022 10:28:53 GMT

how to fix? what function patch the FreeRTOS idle thread.

RE: inv_sqrt() function will increases power

dejans — Tue, 31 May 2022 07:46:07 GMT

Hi,

The issue that you reported is FPU related with existing workaround. However, since you use FreeRTOS, it might be that you need to patch FreeRTOS idle thread.

Best regards,
Dejan

RE: inv_sqrt() function will increases power

eview — Mon, 30 May 2022 10:09:14 GMT

Please check the docx documentationdevzone.nordicsemi.com/.../5826.nRF52840-lowpower.docx

RE: inv_sqrt() function will increases power

eview — Mon, 30 May 2022 09:26:37 GMT

devzone.nordicsemi.com/.../nRF52840-lowpower.docx

RE: inv_sqrt() function will increases power

dejans — Mon, 30 May 2022 08:50:28 GMT

Hi,

Do you use nRF52840-DK or a custom board?

What is the normal current that you get with ble_app_beacon?

Could you please provide more information about your measurement setup?

Do you measure average or peak current?

Best regards,
Dejan

RE: inv_sqrt() function will increases power

eview — Sat, 28 May 2022 01:21:02 GMT

I still don't know how to fix it.

1. I only execute this function once

2.No FPU interrupts

------------------------------------------------------------

a. It is 5mA

static float inv_sqrt(float x)
{

int i = *(int *)&x;

i = 0x5f375a86 - (i >> 1); // this is magic.
x = *(float *)&i;
return 1 / x;
}

b. It is normal, is it use FPU?

static float inv_sqrt(float x)
{

int i = *(int *)&x;
x = *(float *)&i;
return 1 / x;
}

c.It is normal, is it use FPU?

static float inv_sqrt(float x)
{

int i = *(int *)&x;

i = 0x5f375a86 - (i >> 1); // this is magic.
x = *(float *)&i;
return x;
}

RE: inv_sqrt() function will increases power

dejans — Fri, 27 May 2022 12:45:21 GMT

Hi,

What is normal current when you use ble_app_beacon?

This issue might be related to Floating Point Unit (FPU).
You could take a look at these two cases - first, and second.

How long do you use FPU?
Do you have any FPU interrupts?

Best regards,
Dejan

RE: inv_sqrt() function will increases power

eview — Fri, 27 May 2022 10:31:15 GMT

IAR V9.20