NRF Connect SDK Builds/Pristine Builds Ignore Child Image Configuration With Custom Boards

[bryan_aerel]

Hi,

I am using the VSCode nRF Connect extension with nRF Connect SDK v2.0.0 (according to the Toolchain Manager). I have a custom board with a U-Blox NRF5340 module on it. I am running into an issue with the Throughput example where the very first compilation (after running "nRF Connect: Add Build Configuration" in VSCode) will work exactly as expected as it does on the NRF5340DK with a throughput of around 1.25 Mb/s.

However, when I do a pristine build (using the button from the extension) without changing anything, the new build will not use the configuration for hci_rpmsg.conf in the child_image folder and instead seems to use defaults from the sample's configuration. Essentially, this sets CONFIG_BT_BUF_ACL_RX_SIZE to 27 for the network core instead of 251, resulting in extremely slow throughput which is how I noticed this problem in the first place.

This can be easily reproduced without any hardware:

1. Copy the nrf5340dk_nrf5340 folder from ncs/v2.0.0/zephyr/boards/arm into a custom boards folder
2. Add the custom boards folder to VSCode
3. Restart VSCode
4. Create a new application using the NRF Connect extension
5. Choose the Bluetooth: Throughput sample
6. From Custom boards, choose the nrf5340dk_nrf5340_cpuapp board
7. Choose the prj_nrf5340dk_nrf5340_cpuapp.conf configuration
8. Leave everything else default and build
9. Observe build/hci_rpmsg/zephyr/.config where CONFIG_BT_BUF_ACL_RX_SIZE=251
10. Using the extension, click the "Pristine Build" button under the actions menu
11. Observe build/hci_rpmsg/zephyr/.config where CONFIG_BT_BUF_ACL_RX_SIZE=27

What is it that I am doing wrong here? This doesn't seem to happen for me using the provided NRF5340DK board configuration. As far as I can tell from this page, the configuration is set up correctly so I am unsure of why my custom board will not use the configuration for the child image for any builds except the first one. This took quite a while to figure out, I never suspected a problem with the configuration or build tools since the example worked for me the first time; I just thought I messed up the code somewhere when I made a change and rebuilt.

Thank you for you help!

• Windows 10
• VSCode Version 1.70.1
• nRF Connect SDK v2.0.0

[dwalks]

I gave up with the child image and set the conf file via cmake flags instead. It works as expected.