Issue with UART when using RTT Zephyr Shell

RE: Issue with UART when using RTT Zephyr Shell

Sigurd — Tue, 25 Nov 2025 21:24:06 GMT

Another thing you can double-check, is that you have CONFIG_SHELL_BACKEND_SERIAL=n

RE: Issue with UART when using RTT Zephyr Shell

Alex P — Fri, 21 Nov 2025 00:48:35 GMT

I can certainly try, however, there is no issue with UART_TX (it works just fine). I have an issue with UART_RX being intercepted by Zephyr shell, so not sure how your proposal is relevant in this context.

RE: Issue with UART when using RTT Zephyr Shell

Sigurd — Thu, 20 Nov 2025 22:38:11 GMT

Hi!

[quote user=""]NRF_PSEL(UART_TX, 1, 9)[/quote]

Any reason for why you are using this pin? Could you try a different pin ? P1.9 is connected to Button 1 on the DK

RE: Issue with UART when using RTT Zephyr Shell

Alex P — Tue, 18 Nov 2025 05:29:52 GMT

Hi Sigurd,

I have tried (but also even completely removing bias-pull-up), but nothing has changed, really.

I would later need to use the same port in half duplex mode, too.

Is there anything else can be done?

Thanks

WBR,

Alex

RE: Issue with UART when using RTT Zephyr Shell

Sigurd — Sun, 16 Nov 2025 23:12:01 GMT

Hi!
Try this overlay:

	uart20_default: uart20_default {
		group1 {
			psels = <NRF_PSEL(UART_TX, 1, 9)>,
		};

		group2 {
			psels = <NRF_PSEL(UART_RX, 1, 7)>,
			bias-pull-up;
		};
	};

	uart20_sleep: uart20_sleep {
		group1 {
			psels = <NRF_PSEL(UART_TX, 1, 9)>,
				<NRF_PSEL(UART_RX, 1, 7)>,
			low-power-enable;
		};
	};