Verify working of DCDC converter on PCA10056

[Remco Poelstra]

Hi,

I'm using the PCA10056 dev kit to verify the workings of the DCDC converter. I added the following code after nrf_sdh_enable_request():

e = sd_power_dcdc_mode_set(NRF_POWER_DCDC_ENABLE);

When I now use an oscilloscope to check the DCC pin, I never see it switch. I tried connecting to the board using nRF Connect to have the Bluetooth radio active.

How can I verify that the DCDC converter is enabled?

Thanks in advance.

Kind regards,

Remco Poelstra

[Stian Røed Hafskjold]

When you enable the DCDC, it is is automatically controlled, always choosing the regulator that will consume the least current. When the chip is in IDLE the ultra low power regulator is used, and the DCDC is switched off.

Try to enable the DCDC and enable something that consumes current (Like the HF clock). Or prevent the CPU from sleeping in the main loop (removing any WFE/WFI calls), and you will see the switching on the DCC pin

An other way to see if the DCDC is enabled is to check the current consumption. Especially the radio TX/RX peaks will be different with DCDC enabled or not. Have a look at the online power profiler to see what's expected: https://devzone.nordicsemi.com/nordic/power

[Remco Poelstra]

Hi,

Unfortunately I don't currently have access to equipment that can actually measure the current consumption.

Hence, as a sanity check I just wanted to see the pin switch, knowing that I initialized it correctly.

When I place a for(;;) statement just before I start the FreeRTOS scheduler, I still do not see the pin switch.

Should that be sufficient power consumption for the SoC to use the DCDC converter?

[Stian Røed Hafskjold]

Yes, a for(;;) will start the DCDC. Can you try with a main function that looks like this and nothing more?

NRF_POWER->DCDCEN = 1;
for(;;){}

[Remco Poelstra]

That does not start the DCDC converter. I also added NRF_CLOCK->TASKS_HFCLKSTART=1; before the for(;;) and that indeed enables the HFXO, yet still no switching.

As a side note, I do see about 1.3V on the pin.

[Stian Røed Hafskjold]

1.3V is the DC voltage of that pin both when DCDC is enabled and disabled.

What are you using to measure on DCC, and what is the sampling rate? The DCDC is switching at about 8MHz.

[Remco Poelstra]

A 70MHz scope, 1GS/s, horizontal set at 40ns/div.

This setting shows the 32MHz waveform of the HFXO nicely and it should be able to show a 8MHz waveform.