nRF5340DK VCOM only works with putty

[ubat]

Hey guys,

an issue I was postponing but need to solve for an upcoming management demonstration: I can only connect to the nRF5340DK VCOM with putty.

Using Hterm or the Matlab serial port functionality, which is what I need for the demo, will shut down the Jlink cpu. LED5 will turn off, and the Jlink CDC UART port disappears from the device manager.

I tried DTR/RTS pins on and off, to no avail. This solved the problem here nRF52 DK - USB CDC ACM Example not working with HTerm/Qt - Nordic Q&A - Nordic DevZone - Nordic DevZone (nordicsemi.com) e.g., which is similar I guess.

The Jlink cpu seems to reset upon Hterm or Matlab serial connecting. The nRF5340 is still up and going, as indicated by LEDs signaling new received packets.

Any idea?

Thank you,

Uli

[Øyvind]

Hello Uli, 

Can you provide more information on what version of the nRF5340DK you are running and with what application? I will try to replicate here. That said, the JLink CPU should not be affected when connecting via Serial, Do you see 2 serial ports from the device?

Kind regards,
Øyvind

[ubat]

Hi Øyvind,

I'm using version 2.0.0, PCA10095, 2021.42, 1050083097 and two others.

I can see two serial ports from the device; I'm currently using only the network CPU, so only trying to use VCOM0.

One of the freeware applications would be HTerm - der-hammer.

Thank you!

Uli

[Øyvind]

Uli, thanks for providing this information! 

What application are you running on the network CPU? 

[ubat]

Hey,

empty core on the main CPU as required, and PRX (for ESB) on the network CPU. Using Putty or the Visual Studio built-in terminal is working fine, other tools not.

[Øyvind]

Uli, I'm not able to reproduce the issue. I've tried two boards here (v0.11.0 and v2.0.0).

nrfjprog --eraseall -f NRF53 --coprocessor CP_APPLICATION

Then flashed the PRX to CP_NETWORK via the VS Code extension. The Jlink CDC UART ports are still there and LED5 is still lit. I've tried with PuTTy, HTerm and TeraTerm. 

Do you have any special settings on the board itself? Anything connected to the board?