Meaning of: REGULATORS_VREGRADIO_DCDCEN_DCDCEN_Enabled ?

[GerardB]

For power optimization on our nrf5340 project, we followed the recommendations here:

devzone.nordicsemi.com/.../optimizing-power-on-nrf53-designs

We originally did that with SDK v1.9.1. Recently we upgraded to SDK v2.3.0.

As per that article, the first three code lines in our "void main()" are:

NRF_REGULATORS_S->VREGH.DCDCEN = REGULATORS_VREGH_DCDCEN_DCDCEN_Enabled;

NRF_REGULATORS_S->VREGRADIO.DCDCEN = REGULATORS_VREGRADIO_DCDCEN_DCDCEN_Enabled;

NRF_REGULATORS_S->VREGMAIN.DCDCEN = REGULATORS_VREGMAIN_DCDCEN_DCDCEN_Enabled;

Although everything seems to work well, I would appreciate it if you could explain the exact purpose and meaning of the 2nd last line above, ie: 
"...= REGULATORS_VREGRADIO_DCDCEN_DCDCEN_Enabled;"

Questions:

1. What exactly does that line do?

2. Is it still necessary in SDK v2.3.0?

3. How (or why) does this "save/optimize power"?

Thanks!

Gerard

[GerardB]

Thanks Maria,

I actually tested this by using setting it only in prj.config and reading (instead of writing!) those 3 registers in main() - to confirm that they are set. So seems to work perfectly.

Used this code in main():

// power savings strategy. For more details, see prj.config and:
// https://devzone.nordicsemi.com/nordic/nordic-blog/b/blog/posts/optimizing-power-on-nrf53-designs
// Voltage regulators are set in automatic DC/DC mode (as opposed to default LDO mode), in prj.conf:

// CONFIG_BOARD_ENABLE_DCDC_APP=y
// CONFIG_BOARD_ENABLE_DCDC_NET=y
// CONFIG_BOARD_ENABLE_DCDC_HV=y 

// So we don't need these three registers:
    
// NRF_REGULATORS_S->VREGH.DCDCEN = REGULATORS_VREGH_DCDCEN_DCDCEN_Enabled;
// NRF_REGULATORS_S->VREGRADIO.DCDCEN = REGULATORS_VREGRADIO_DCDCEN_DCDCEN_Enabled;
// NRF_REGULATORS_S->VREGMAIN.DCDCEN = REGULATORS_VREGMAIN_DCDCEN_DCDCEN_Enabled;
    
// to be set in "code" here (as per above linked blog) as they are automatically preset
// when including the above three lines in prj.config:
    
// NRF_REGULATORS_S->VREGH.DCDCEN = REGULATORS_VREGH_DCDCEN_DCDCEN_Enabled;
// NRF_REGULATORS_S->VREGRADIO.DCDCEN = REGULATORS_VREGRADIO_DCDCEN_DCDCEN_Enabled;
// NRF_REGULATORS_S->VREGMAIN.DCDCEN = REGULATORS_VREGMAIN_DCDCEN_DCDCEN_Enabled;

// check and prove/confirm that the Voltage Regulator registers are setup for "DC/DC" mode.
    if (IS_ENABLED(CONFIG_LOG) && IS_ENABLED(CONFIG_USE_SEGGER_RTT)) {
        if ( (NRF_REGULATORS_S->VREGH.DCDCEN == REGULATORS_VREGH_DCDCEN_DCDCEN_Enabled)
            &&  (NRF_REGULATORS_S->VREGRADIO.DCDCEN == REGULATORS_VREGRADIO_DCDCEN_DCDCEN_Enabled)
            && (NRF_REGULATORS_S->VREGMAIN.DCDCEN == REGULATORS_VREGMAIN_DCDCEN_DCDCEN_Enabled) ) 
        {
            LOG_INF("ALL Voltage Regulators confirmed to be in DC/DC mode for power optimization.");
        }
        else {
            LOG_ERR("Some Voltage Regulators may NOT be set in DC/DC mode!?");
        }
    }

Thanks again for your clear guidance - much appreciated - now closing this case.

Regards

Gerard