Issue with HCI Communication on nRF5340

[Yash48]

Hello Nordic Support,

I am trying to use the nRF5340 SDK to communicate directly with the network core via HCI commands, without going through the application core.

Steps I have taken so far:

1. Built the hci_uart example from the nRF SDK (default configuration).

2. The build generates only one firmware image (apparently the application core image).

3. After flashing this image to the device and sending HCI commands, I receive no response.

Expected behavior:

• I want to communicate directly with the network core via HCI commands.

• I expect the device to respond to HCI commands without requiring the application core.

Questions:

1. How can I build and flash the network core firmware so it can handle HCI commands directly?

2. Is there a supported Nordic example for HCI communication directly with the network core?

3. Are there any specific configurations or steps I need to enable HCI on the network core?

[Edvin]

Hello,

In case you did, please avoid using AI to formulate your questions.

So you want to communicate directly with the network core, with a UART instance controlled by the network core, is that the case?

Built the hci_uart example from the nRF SDK (default configuration).

I assume you mean the nRF Connect SDK, not nRF5 SDK? What was your build command? What was the board target that you built for? And what NCS (nRF Connect SDK) version are you using?

Questions:

1: We don't have any sample doing this exactly.

2: No, not out of the box.

3: probably.

So you have the hci_uart sample, that you found in the nRF Connect SDK. You would have to build it for the nrf5340dk/nrf5340/cpunet, in order to target the network core. This then probably requires an nrf5340dk_nrf5340_cpunet.overlay file to provide the correct uart instance and uart pins.

Then you need to flash something on to the application core in order for it to start the network core. You can use the NCS\nrf\samples\nrf5340\empty_app_core for this. As long as this is flashed to the network core, it will boot up the app core, start the network core with whatever is programmed on it, and then go to sleep with the application core.

What do you intend to use the application core for, if I may ask?

Best regards,

Edvin

[Yash48]

 Hi Edvin, thanks for the help — I’ve solved the issue now.