undefined reference to `__device_dts_ord_98'

[NicolasK.]

I'm trying to use implement the real time clock rtc0. This is what I did:

I enabled CONFIG_RTC=y in the prj.conf.

&rtc0 {
            compatible = "nordic,nrf-rtc";
            reg = < 0x4000b000 0x1000 >;
            cc-num = < 0x3 >;
            interrupts = < 0xb 0x1 >;
            status = "okay";
            clock-frequency = < 0x8000 >;
            prescaler = < 0x1 >;
};

in the overlay file

#include <zephyr/kernel.h>
#include <zephyr/device.h>
#include <zephyr/drivers/rtc.h>

#define RTC_0 DT_NODELABEL(rtc0)
const struct device *timer_dev = DEVICE_DT_GET(RTC_0);
const struct rtc_time time;

int main(void)
{
        rtc_set_time(timer_dev, &time);
        return 0;
}

in the main

After I added rtc_set_time(timer_dev, &time); it fails to link the C executable zephyr/zephyr_pre0.elf with the error: undefined reference to `__device_dts_ord_98'

What did I forget to do or did wrong? I have the feeling I'm missing something like an additional initiation type function but there is very little documentation on how to actually set it up.

[helsing]

Hi Nicolas,

Does it help to if you try 'rtc' instead of 'rtc0' in the overlay file?

[NicolasK.]

That doesn't work (I tried it). rtc0 already exist in the nrf53840.dtsi (not the .dts) aswell as rtc1 and rtc2. Im using the " &rtc0 { " to point to that location and overwrite its parameters. The only important piece in the overlay is the status = "okay" to enable rtc0 because by default its status = "disabled". The timer_dev seems to be set correctly because there is no complie error, but when I add the rtc_set_time function it gives me said error. :(

[helsing]

Hi Nicolas, sorry for the delay. I will get back to you tomorrow.

[helsing]

rtc_set_time is a part of the Real Time Clock drivers in Zephyr while nordic,nrf-rtc is Real Time Counter. These are not the same.

For real time clock one often needs an external module. For real time clock, there is a Zephyr test here: https://github.com/nrfconnect/sdk-zephyr/tree/main/drivers/rtc

[RuthA]

Hi Helsing,

I'm seeing the same behaviour with an nRF52 dev kit.

DEVICE_DT_GET( DT_NODELABEL( XX ) )

works for other node labels and it looks like it expands to the correct "__device_dts_ord_XX" number for the rtc nodes (rtc0, rtc1 and rtc2 on my system) when checked against the "devicetree_generated.h" file. However, the "rtc_set_time" function can't use the device and I see the same "undefined reference" error as Nicolas (with a different number).

This method of setting the device and then using "rtc_set_time" seems to follow the procedure in this zephyr test: https://github.com/zephyrproject-rtos/zephyr/blob/a51bd53cef2b2b6cacb1dc7a366adb45565659f3/tests/drivers/rtc/rtc_api/src/test_time.c

Can you explain why it's not working or let me know which external modules we need for the real time clock?

Best wishes,

Ruth