The JLink UART (COM) Port disappears

[Sanju]

Hi,

When I connect nRF52833-DK device to the (Windows 10) system, its JLink UART (COM) Port disappears after some time (in about 4 to 5 minutes.)
The following screenshot shows the said COM port properties in Windows 10 "Device Manager".

The device COM port works well as long as it maintains connection (appears on Device Manager for 4 to 5 minutes.) Thereafter the COM port disappears.
How to recover the COM port of nRF52833-DK?

Regards,
Sanju

[Hung Bui]

Hi Sanjiv, 

I assume after the COM Port disappear if you unplug and plug it back it appeared again ?
How do you connect the board to the PC ? Please try to connect it directly to the PC without any USB hub. Also try another USB port. 

Do you have any power saving mode on the PC ? From what you described it sounds like a power saving mode. 

[Sanju]

Hi Hung,

Yes, after the disappearance of COM port, unplugging and plugging it back makes it appear again for a brief period (4 to 5 minutes.) I didn't (and do not) use any USB hub to connect nRF5283-DK to the system - I connect it directly. The device exhibits the same behavior when connected to other USB ports of the system.

The system doesn't have any power saving mode on. My other nRF52833-DK units don't exhibit such issue.

As discussed in the following ticket, would flashing the device with Interface MCU firmware help reclaim the JLink port?

devzone.nordicsemi.com/.../jlink-interface-firmware-download

[Hung Bui]

Hi Sanjiv, 
You can try updating the firmware of the Interface MCU, but I can't say for sure it would fix the issue. 
You can download the firmware from here: https://www.nordicsemi.com/Products/Development-hardware/nRF52833-DK/Download?lang=en#infotabs

If other board doesn't show the same issue then it must be something wrong with the Interface MCU. Hope that reflashing it would fix.