FreeRTOS Tickless Idle vs Tick Current Consumption

[WestCoastDaz]

We have been comparing the current consumption of the nRF52 running FreeRTOS Tickless Idle versus a constant tick and using the idle task to sleep and the results are interesting, see below.

June 7th Edit: SDK 11, SoftDevice S132 2.0.0.0, Silicon is QFAABB (Rev C)

Tickless Idle:

• Average current is 390uA

Tick with Idle Task:

• Average current is 303uA

Both runs were identical with the floating point interrupt handler implemented as in this post devzone.nordicsemi.com/.../, same number tasks/execution profile, same tick rate, advertising off. The only difference is tick mode uses the idle task hook to put the processor to sleep.

Note the follow images were captured using our own Labview tool sampling at 8kHz. Ignore the bottom trace

Tickless Idle

Tick with Idle Task

[inghowe83]

Hi Darren,

May I know what was the latest current consumption for your tickless project? What will be the current difference between system on Idle vs freeRTOS tickless?

[WestCoastDaz]

inghowe83 I don't have updated results in a form that I can share at the moment.  This post is quite old and used very early versions of the S132 and SDK for the nRF52832.  What I can tell is that for a recent project using S132 4.0.3 and SDK 13.0.0 which uses FreeRTOS in tickless idle we were getting an average quiescent current of ~110uA at 2.5V for normal operation with no advertising.

Does this help?

[mtsunstrum]

From https://devzone.nordicsemi.com/f/nordic-q-a/35386/application-with-freertos---lowest-possible-current-in-idle it looks like one was able to get down to 9uA (when no advertising)

[inghowe83]

Thanks! It does help.

[WestCoastDaz]

inghowe83 I forgot to mention that the ~110uA I quoted was on a design where most of the current was due to a lot of leakage through various protection circuits.