Change UART baud rate NRF5340 w/ NRFConnect SDK

[RJengr]

Hello,

I am wondering where to change the baud rate for the UART in the NRFConnect SDK using zephyr. I am working with the peripheral_uart example.

Thanks,

RJ

[Simon]

Try adding an overlay file nrf5340dk_nrf5340_cpuapp.overlay (use the same board-name as the one you're bulding with) to your project with the following content:

&uart0 {
	status = "okay";
	current-speed = <new baud rate>; //<115200>;
};

That will overwrite the default speed set in <ncs location>\zephyr\boards\arm\nrf5340dk_nrf5340\nrf5340_cpuapp_common.dts

Best regards,

Simon

[RJengr]

There is a prj.overlay file in the project already with a declaration of Uart0. is this the same?

[Simon]

I talked to the developer of the central_uart and peripheral_uart samples and the file prj.overlay does basically nothing. The file will be removed soon. Please add it to an overlay file in the following manner: <board name>.overlay. Check out Set devicetree overlays for more information about this.

Best regards,

Simon

[RJengr]

Simon I changed the baud rate in the overlay file. However, it is still outputting a baud rate off 115.2k instead of a baud rate of 9600. See logic analyzer data and overlay file below. 

/* SPDX-License-Identifier: Apache-2.0 */

&uart1 {
	compatible = "nordic,nrf-uarte";
        current-speed = <9600>; //<115200>;
	status = "okay";
	tx-pin = <33>;
	rx-pin = <32>;
};

[Simon]

Have you checked what it's set to in the file <application>/<build>/zephyr/zephyr.dts? Search for uart1 an check what current-speed is equal to.