hw-flow-control fails on nRF9160DK VCOM1 if I add it to device tree, even though the schematic shows the signals all connected to the nRF52840

[Burt]

I have tried several code samples: nrf/samples/bluetooth/peripheral_uart and nrf/samples/openthread/cli. If I set hw-flow-control in zephyr/boards/nordic/nrf9160dk/nrf9160dk_nrf52840.dts for uart0, there is no communication possible through vcom1 to my computer. I have not tried different computers -- this one is Lenovo P51 running Ubuntu 24.04. It was kind of a weird thing for me to enable hw-flow-control, but it happened when I was trying to get openthread/cli running and I saw that some other platforms use hw-flow-control. Any thoughts? Oh, yeah, I am running Serial Terminal on my Ubuntu and I did set RTS/CTS to on (in case default was different). I almost closed this ticket, but when AI said it was due to my misconfigured computer, but I know I have Serial Terminal set up correctly, I figured I'd have you take another look.

Burt

[Hakon]

Hello,

what terminal emulator are you using, and what are the settings?

[Burt]

Hello Hakon,

I used Serial Terminal from nRF Connect, on Ubuntu, like I mentioned. All settings were default except I changed RTS/CTS to "on". Line mode and shell mode both have the issue. Let me know if I you need more details.

Burt

[Hakon]

Can you tell me what NCS branch/version you are on, so I can try to reproduce the error you are seeing?

[Burt]

Oh, yeah, SDK v3.3.0.

[Hakon]

I'm not able to reproduce this. I tried running hello_world sample with hw-flow-control in dts on the nrf9160/nrf52840, and using Serial Terminal on windows, and also running picocom on Ubuntu 24.04. I can also try with serial terminal on Ubuntu if you think the issue is specific to this setup. But can you try using other terminal emulators to see if it makes a difference?