nRF Connect Programmer gives LIBUSB ERROR NO DEVICE

[brianreinhold]

I have an encased nRF52840 dongle that is visible to nRF Connect. However, when I try and select the displayed device I get the following:

09:07:39.925	DFU trigger interface found, changing to bootloader...
09:07:39.925	LIBUSB_ERROR_NO_DEVICE
09:07:39.925	Target device closed.

I cannot press the reset button since the dongle is enclosed. Why does this error occur and what can I do to fix it?

I am running on Windows 10.

Before trying to select the display device the drop down shows:

• Serial Port COM11
• USB Nordic Semiconductor nRF52 Connectivity

[brianreinhold]

Okay, that's good to know. I am unable to reproduce the condition myself I will have to send it to my coworker for testing. But in our use case it does not appear to be an issue as the dongle is meant to be plugged into something like a USB phone charger in the same room as the stationary bike. Power will always be supplied - no batteries involved. 

If we ever have a need for a battery version, we can address the problem then. Not sure how much extra power we are really talking about anyways. Sometimes it seems we make mountains out of power issues which are trivial compared to the other concomitant operations.

[brianreinhold]

According to my workmate, the setting of the USBD_POWER_DETECTION to false solves the problem. I do not think this will be a problem in production as the dongle will most likely be externally powered by a phone charger or the like.

[ovrebekk]

Hi Brian

It is good to hear that the USBD_POWER_DETECTION setting solved the issue

As for the additional power consumption this should be negligible when the CPU is running, but in sleep mode it could make an impact (where you might otherwise see a couple of microamps you will now see hundreds of microamps). 

Best regards
Torbjørn