nRF5340-DK : trouble with hci_uart sample

[loic murith]

Hi !

I want to send simple HCI commands, such as reset, to the nRF5340 via UART. Therefore, I'm using the sample "hci_uart" available with nRF Connect SDK v1.5.0. I am sniffing the UART lines on the dev. kit with a logic analyzer but I cannot manage to measure anything. To try to understand what is going on, I put some breakpoints in the code and I observed that SoC never reaches the code in the while(1) loop in the main and systematically gets stuck in the file "cpu_idle.S". Is it normal ?

I did not modify anything in the code but I can imagine I do something wrong... please, can anybody help me clarifying this issue ?

I am available to give you any other information.

Kind regards.

[loic murith]

To be more precise, the nRF5340 is stuck in the bt_rpmsg_open() function. Do you know what does it involve ? What would be the cause ?

Kind regards.

[Carl Richard]

Hello, Loic!

Which of the two cores are you targeting with the sample? To use hci_uart with the nRF5340 For any HCI sample I believe you must use the network core, as the application core doesn't have access to radio resources.

Best regards,
Carl Richard

[loic murith]

Hello Carl!

Thank you for your reply. As far as I understood, the network core does not support the HCI UART : (+) Is nrf5340 support only bluetooth hci_uart mode on cpunet? - Nordic Q&A - Nordic DevZone - Nordic DevZone (nordicsemi.com)

Just to avoid miscomprehension, I am selecting the board variant "nrf5340dk_nrf5340_cpuapp" and I selected the code sample available in "ncs\v1.5.0\zephyr\samples\bluetooth\hci_uart".

I am not sure if I understood it right but here is how I see it : the hci_uart sample code exposes the HCI interface of the network core over the UART of the application core. Is that right ?

If it is correct, that's why I am currently building the sample code on SEGGER Embedded Studio for the application core. I tried to do it for the network core but I couldn't get it working...

If you need any other detail, I will be happy to answer you !

Kind regards,

Loïc

[Carl Richard]

Hello again!

loic murith said:

Thank you for your reply. As far as I understood, the network core does not support the HCI UART : (+) Is nrf5340 support only bluetooth hci_uart mode on cpunet? - Nordic Q&A - Nordic DevZone - Nordic DevZone (nordicsemi.com)

What's meant with the answer here is that the only HCI sample that we currently can ensure support for on the nRF5340 network core is hci_rpmsg. However, from what I can see hci_uart should work on both of the cores given the correct configuration and overlays. Please have a look in the board folder of the hci_uart sample and look at the files there for reference. For the nRF5340 application core a file called "nrf5340dk_nrf5340_cpuapp.overlay" is required. In this file you can also specify the desired UART pins to use.

Best regards,
Carl Richard

[loic murith]

Hello again Carl!

Thank you very much for this information. I checked the file which contains the following lines :

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

&uart0 {
compatible = "nordic,nrf-uarte";
current-speed = <1000000>;
status = "okay";
hw-flow-control;
};

Actually, when I manage to sniff data on UART line such as "*** Booting Zephyr OS build v2.4.99-ncs1  ***" I see that the baudrate is 115200 and not 1000000 as specified in the .overlay file. Do you know what could cause this ?

Moreover, can you please explain me what can I add in this file to specify the UART pins ?

Thank you very much for your help !

Kind rgards,

Loïc