GRTC issues on a custom board

RE: GRTC issues on a custom board

Edvin — Thu, 03 Jul 2025 12:58:45 GMT

What board files are you building your application with?

Can you try to remove the devicetree overlay file? Just build it without that one, and see if the behavior is the same. I just recently tested a PCB that didn't have the LFXO, and I only used these two:

CONFIG_CLOCK_CONTROL_NRF_K32SRC_RC=y
CONFIG_CLOCK_CONTROL_NRF_K32SRC_XTAL=n

For testing, you can also try to add this:

# Disable the unsupported driver
CONFIG_NRFX_TIMER0=n

# Enable the necessary drivers
CONFIG_NRFX_TIMER10=y

Although I don't think they are necessary for the hello_world sample.

Best regards,

Edvin

RE: GRTC issues on a custom board

ian1442 — Mon, 30 Jun 2025 08:20:54 GMT

Hi,

First of all, thank you for your help!

I've implemented the changes you recommended, but I'm still getting the same error.

Here's my prj.conf:

# nothing here

CONFIG_LOG=y

CONFIG_USE_SEGGER_RTT=y

CONFIG_LOG_BACKEND_RTT=y

CONFIG_UART_CONSOLE=n

CONFIG_RTT_CONSOLE=y

CONFIG_PRINTK=y

CONFIG_DEBUG_OPTIMIZATIONS=y

CONFIG_NORDIC_SECURITY_BACKEND=n

CONFIG_DEBUG=y

CONFIG_DEBUG_INFO=y

CONFIG_DEBUG_OPTIMIZATIONS=y

CONFIG_ASSERT=y

# Enable MPU

CONFIG_ARM_MPU=y

CONFIG_CLOCK_CONTROL=y

CONFIG_CLOCK_CONTROL_NRF=y

CONFIG_NRF_GRTC_TIMER=y

CONFIG_NRF_GRTC_START_SYSCOUNTER=y

CONFIG_CLOCK_CONTROL_NRF_K32SRC_RC=y

CONFIG_CLOCK_CONTROL_NRF_K32SRC_FREQUENCY=32768

# Disable LFXO (external 32kHz crystal)

CONFIG_CLOCK_CONTROL_NRF_K32SRC_XTAL=n

# Disable synthesized LFCLK from HFCLK

CONFIG_CLOCK_CONTROL_NRF_K32SRC_SYNTH=n

CONFIG_CLOCK_CONTROL_NRF_K32SRC_500PPM=y

CONFIG_CLOCK_CONTROL_NRF_K32SRC_RC_CALIBRATION=y

CONFIG_CLOCK_CONTROL_NRF_CALIBRATION_LF_ALWAYS_ON=y

and the devicetree overlay:

/delete-node/ &lfxo;

&grtc {

/delete-property/ clocks;

/delete-property/ clock-names;

clocks = <&pclk>;

clock-names = "hfclock";

};

Am I missing something?
I'm building this on ncs 3.0.1, with 3.0.1 toolchain

RE: GRTC issues on a custom board

Einar Thorsrud — Fri, 27 Jun 2025 11:50:35 GMT

Hi,

Based on that you see PC at nrfy_grtc.h file, line 300 and the thread you link to it seems that there is no functioning 32.768 kHz crystal. If so, you need to do everythign explained in this post (including implementing the changes in the linked pull request, as those are not yet in nRF Connect SDK, not even in main at the time of writing). You also need the clock related configs from this post (from he same thread).

I see that the documenation for ISP2454 states that it has a 32.768 kHz crytal though, so it could be that there are problems with some devices, or that the load cap configuration is incorrect for the crystal (see here for how it is configured in the board files for the DK)? In any case, that should not be a problem if you use LFRC, so it is wroth it as an experiment.