High BLE fail rate on custom nRF5340 board

[nickyblanch]

Hi all,

I have a batch of eight custom boards based around the nRF5340. Three of them work flawlessly, and the rest have assorted digital communication issues, BLE issues, or both. One board can't even initialize the BLE radio. When calling bt_enable(), the following error is returned:

Two other boards don't produce a BLE signal, but don't show any errors.

Another one of the nRF5340 chips will show up under 'Devices' when connected to nRF Connect SDK, but clicking on it (in an attempt to connect to any of the communication ports) returns this error:

Because the firmware works on three of the boards, the issue is definitely hardware related - could poor solder connections under the aQFN94 package cause these errors? Or could any mistakes in the board assembly process damage the nRF chips and cause these?

Thanks,

Nick B

[Kenneth]

Hello,

If you haven't already you should make sure you have followed:
https://devzone.nordicsemi.com/guides/hardware-design-test-and-measuring/b/nrf5x/posts/general-pcb-design-guidelines-for-nrf53-series 

short story; copy the layout exactly is the safe bet.

Once you have the hardware populated you should run the radio test to confirm the board operated as intended:
https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/nrf/samples/peripheral/radio_test/README.html 

short story; measure the output power and carrier frequency on a spectrum analyzer.

In terms of the failure you see in specific, you may try to use the internal RC for the 32kHz as specified here:
https://devzone.nordicsemi.com/f/nordic-q-a/100610/bt_dev-drv--open-fails-with-bt_hci_driver-bt_rpmsg_open-endpoint-binding-failed-with--11-error  

Kenneth