Use USB on nRF9160DK while set up for current measurements?

[ERIK]

Can I still use the USB while the nRF9160DK is set up for current measurement as described in the spec, where power is applied on P28 after cutting solder bridge SB43 and stuffing 0.5 ohm resistor R60?

https://infocenter.nordicsemi.com/topic/ug_nrf91_dk/UG/nrf91_DK/prepare_board.html

Or, do I need to either reconnect SB43 or short the two uppermost pins of P24 in order to use the USB again?  No need to do anything with R60 after it is there, as far as returning to normal operation?

Thanks,

Erik

[ERIK]

I think I have found a partial answer in the spec, in the section on Power Supply.

https://infocenter.nordicsemi.com/topic/ug_nrf91_dk/UG/nrf91_DK/hw_power_supply.html

This states that the circuitry will only use one power source at a time and they are prioritized, with USB the highest and P28 the lowest.  I think that means that I can use the USB after modification to measure current with a scope, but that the supply actually used if both USB and P28 are powered will be the USB, so no current measurements should be made while both are connect.

I assume that the USB in that case will not just be powering the DK but will also be operable for communication for programming, debug, etc.

Correct?

[haakonsh]

ERIK said:

I assume that the USB in that case will not just be powering the DK but will also be operable for communication for programming, debug, etc.

The USB is prioritized because a USB source is usually mains powered or have a large battery, while the regular power supply is usually a small battery. While the USB is powering the nRF91 it can still be used for communication.

[ERIK]

So, please confirm for me.  If I set up my DK board to measure current with a 'scope as shown in the spec

https://infocenter.nordicsemi.com/topic/ps_nrf9160/pmu.html#unique_1555866438  (cut SB43)

https://infocenter.nordicsemi.com/topic/ug_nrf91_dk/UG/nrf91_DK/hw_measure_oscilloscope.html  (install resistor across R60)

do I need to short the two uppermost pins of P24 before using a USB for debugging, or not?

[haakonsh]

Yes, by shortening those pins the nRF_VDD is supplied by the DK's voltage ragulator, that's supplied by the debug USB. If these two pins are not connected the nRF9160 will not be powered.