hci_uart not responding at higher baudrates on NRF52810

[jjamesson]

Hi , Zephyr community,

I am having an issue with the hci_uart sample, where I am not getting a response from the controller for the HCI RESET command on higher UART bandwidth, namely with the "sudo btattach -B /dev/ttyACM1 -S 1000000 -P h4" command. However, I do get the response when using 115200 as the baudrate. I am using an oscilloscope to see if the signal gets a response or not.

The problem exists with the "nrf52810_pca10040" west build, but the problem does NOT exist on the "nrf52_pca10040" west build (meant for using with the 52832 chip). The custom hardware we plan on deplaying hosts the 52810 controller, so this is an issue for us.

I have tried both the newest Zephyr and Zephyr 1.14 to solve this problem.

Hope you can help. Feel free to ask additional information about this issue.

With regards,
James

[carlescufi]

@jjamesson I assume you are using an nRF52 DK (PCA10040)?

[jjamesson]

@carlescufi Yes, I am. Sorry for not mentioning.

[carlescufi]

@jjamesson actually, have you tried adding an overlay for the board?
You need a file like:
https://github.com/zephyrproject-rtos/zephyr/blob/master/samples/bluetooth/hci_uart/boards/nrf52dk_nrf52832.overlay

but for nrf52dk_nrf52810. So you need a new file:
samples/bluetooth/hci_uart/boards/nrf52dk_nrf52810.overlay

Identical to the current `nrf52dk_nrf52832.overlay.

[carlescufi]

Alternatively, just change the baud rate directly to 1000000 here:
https://github.com/zephyrproject-rtos/zephyr/blob/master/boards/arm/nrf52dk_nrf52810/nrf52dk_nrf52810.dts#L95

[jjamesson]

@carlescufi Indeed, I figured shortly after writing this post that there was no overlay file for the DK hosting the nrf52810 chip, and modifying the .dts file solved this issue. Thanks for looking into this. This topic can be closed.

With regards,

[carlescufi]

Thanks for letting us know @jjamesson