Dev system says usb device malfunctioned

I am now working from home, with a new dev machine and trying to get up and running. I have our board with 20260. I has been loaded with bootloader, firmware, and our application and will boot up correctly. However when i plug in the usb cable, the dev machine indicates the usb device malfunctioned. And of course, the device ( 20260 etc) does not show up in the DeviceManager.

What am I missing ??

But same device work on other pc?

Direct connect to PC or using a USB hub?

Did you try to add power pack and not rely on the USB power?

same device and cables work fine with pc at work.

direct connect to pc. There are about 10 usb ports on the pc. On some of them, the sc20260 shows up in ‘Other Devices’

OUr board is powered by a separate 24V power supply

How is your USB routing on the custom board? I ask because I have seen issues in the past when the traces do not adhere to the USB spec.

Do you have ESD protection on the USB lines?

I’ve just completed an SCM20260D board with USB tracks that are approx 80mm long but I was careful to ensure they were within spec.

Dave, what do you consider as USB tracks?
Is it D+ and D- up til SCM20260D?

Yes. D+ and D- need to follow rules for differential pairs with 90 ohms impedance. Hopefully your PCB software has differential pair settings.