sd_power_dcdc_mode_set behavior

[ms360]

Other than setting the DCDC_MODE_PIN, what else does the sd_power_dcdc_mode_set() do? 

I'm seeing an issue where I have a GPS peripheral on UART that is seeing about 10dB less RSSI when I use the sd_power API. 
If I use GPIO to control DCDC_MODE_PIN, I don't see the 10dB loss, and BLE still works. 

I cannot explain this behavior at all, but I have a repeatable way to replicate this issue. 

Trying to understand what exactly goes on in sd_power_dcdc_mode_set(). 
I don't see any links to detailed documentation when I search for that function call. 

Any help is appreciated. 

[Turbo J]

The switching mode DCDC can produce a lot more noise in the circuitry compared to the linear regulator, and a GPS antenna would be sensitive to that. Read: You have a self inflicted EMI problem.

You could have a nordic employee look at your layout in a private ticket.

I would try using an RF can like you see on many NRF modules (its the small metal cover over the BTLE chip and DCDC inductors).

No idea why you mention a GPIO here, the sd_power_dcdc_mode_set() does not care about any GPIOs AFAIK.

[ms360]

Thanks Turbo J. I was afraid this would be the case. 

Regarding GPIOs - There is something misleading on the schematic. 
P1.14 is labeled as DCDC_MODE and I assumed it was coupled to the switcher. 
(I'm new to the project) 

Regarding the can, they used the BT840x module, so it is canned. 

I will take your advice and create a ticket. Thanks!