Powering USB Host Shield by nRF52840DK pca10056

[ai212983]

Dear Nordic Semi, ladies and gentlemen!

I'm working on a prototype device with USB host functionality. I am using Arduino USB Host Shield connected to nRF52840 DK. DK is connected and powered via J2 USB (MCU) connector. USB Host seems to be powered, and even provides power to the mouse, if plugged in.

But shield internal oscillator doesn't start, even if nothing is plugged in. I guess there's not enough power for that. Shield' operating voltage is 5V, 400/500 mA. It has no power jack and is powered only when attached to an Arduino board.

So the question is: what are my options to provide enough power to this shield to verify if its internal oscillator starts?

Many thanks.

[ketiljo]

Hard to say, please ask the manufacturer of the shield.

[ai212983]

Well, I'm not sure how they can help here. They provided power specs, its up to hosting board to provide it.

Probably I have to measure power provided by DK to the shield?

Is there ways to increase it? Switch to USB power and use both J2 and J3? Use VIN at P20?  

[ketiljo]

Try to power it externally. 500 mA is above what the DK can provide.

[ai212983]

Documentation claims DK is compatible with Arduino modules, but if it can't provide same power as Arduino, it is not, obviously. How much DK can provide then?

Should I try to power externally DK or shield itself? If DK, then how I should do that - with VIN or somehow else?

If shield itself - given there's no power jack, is there way to do it safely? I guess just attaching power to P7 Arduino interface connector is a bad idea?

[ketiljo]

I'd break the power supply between the DK and the shield and power the shield from a 5 V power supply 

[ai212983]

Yeah, that would be most straightforward solution, but that would require some soldering or pin cutting, I guess. If I will just apply power to P7, is board protected from that? Or is there any other way without altering hardware?

[ketiljo]

You can find the HW description here: https://infocenter.nordicsemi.com/topic/ug_nrf52840_dk/UG/nrf52840_DK/hw_desc_intro.html and the schematic and layout here: https://www.nordicsemi.com/-/media/Software-and-other-downloads/Dev-Kits/nRF52840-DK/nRF52840-Development-Kit---Hardware-files-1_0_0.zip

Why don't you just use the USB interface already in the nRF52840?

[ai212983]

I've seen hardware files, thanks. Sadly I lack electronics knowledge, that's why I am asking for help on forums.

The reason I am not using USB interface in nRF52840 because I need USB Host functionality. It is specified in the title of this ticket and in the very first sentence of the description, right after salutation.

According to specification and numerous posts on this forum, nRF52840 (nor any other nRF device) can't function as USB host.

[ketiljo]

The 5V is supplied with a boost regulator, U12. This should be capable of delivering 1 A. But this of course depends on the current is has available on the input. Have you measured the 5V on header P1 or P13 when the shield is in place?

If that drops too much, you should supply the DK with a better power supply as the USB connector, J2, may not be able to provide that much. Connect the power supply to P21