Zephyr Custom board specification

RE: Zephyr Custom board specification

Einar Thorsrud — Wed, 29 Sep 2021 13:10:46 GMT

I am not able to explain problems with disabling UART1 that. I tested with a random example (Bluetooth peripheral LSB) and disabled uart1 in an overlay, but did not see any issues. If I disable UART0 however, there are problems. This is used for logging. If I disable logging by setting CONFIG_LOG=n and CONFIG_SERIAL=n in prj.conf this issue is resolved. Can you test that on your end?

RE: Zephyr Custom board specification

CktDesigner — Tue, 28 Sep 2021 16:24:19 GMT

Hi Einar,

Thanks for this list. I remember seeing this before.

However I'm finding that if uart1 is "disabled" in the .dts file, BLE advertising doesn't occur (even though it is started with no error reported). If I specify it to be "okay", advertising occurs as expected (however when a connection occurs, it drops randomly later).

There also seems to be a dependence with uart0. I commented out the zephyr dependence (zephyr, console = &uart0; ... zephyr,bt-c2h-uart = &uart0;)

I'm trying to determine where "uart0" and "uart1" are used and what seems to be dependent on them, and what the linkage to BLE might be.

Any thoughts? Is there another list of peripherals that zephyr must have ownership of (my prj.conf file has "CONFIG_UART_CONSOLE=n"

Thanks!

RE: Zephyr Custom board specification

Einar Thorsrud — Wed, 22 Sep 2021 07:42:43 GMT

The SoftDevice controller as well as the Multiprotocol Service Layer (MPSL) which it relies on reserves several peripherals, and limits access to others.

You can refer to MPSL and SoftDevice controller documentation for details, but snipping out the relevant parts:

The following peripherals are owned by MPSL and must not be accessed directly by the application:

RTC0
TIMER0
TIMER1, for the nRF53 Series
RADIO
CLOCK
TEMP
PPI channel 19, 30, 31, for the nRF52 Series
DPPI channels 0 - 2, for the nRF53 Series

The following peripherals are owned by the SoftDevice Controller and must not be accessed directly by the application:

ECB
AAR
NVMC
PPI channels 17 - 31, for the nRF52 Series
DPPI channels 0 - 13, for the nRF53 Series

RE: Zephyr Custom board specification

CktDesigner — Tue, 21 Sep 2021 17:48:41 GMT

Thanks. Yes, I looked at the log and didn't see any errors reported.

I went back to the original nRF52840 DK .dts file and used an overlay file to start removing peripherals I wasn't using. I found that disabling uart0 caused the BLE advertising to not appear!

My custom board uses a Laird BL654PA module (nRF52840 + power amp), so I'll check with them to see if there is some dependence on uart0. I looked in the Zephyr documentation to try to find a list of nRF52840 resources used by the BLE driver, but didn't find anything. When using Zephyr with CONFIG_BT_LL_SOFTDEVICE_DEFAULT=y I assume that a Nordic SoftDevice is being used, but am not sure what resources it requires. Is there a list of "reserved resources" that you can recommend?

Thanks!

RE: Zephyr Custom board specification

Einar Thorsrud — Tue, 21 Sep 2021 07:55:54 GMT

Hi,

What happens if you use exactly the same configuration as the nRF52840 DK, and not disable any peripherals? Could it be that you accidentally disabled something that is needed by the Bluetooth stack for instance? Did you check the log or do any debugging? If so, what did you find?

If you don't make progress, perhaps you can upload the project here so that I can look at it?