Using GRTC to output the LFCLK via GPIO (sourced from an external 32.768 kHz crystal)

Hi! I am designing a nRF54 based motion tracker that has an IMU onboard which can take an external clock signal for improved timing accuracy.
Initially I had thought of just placing an external oscillator on the board solely for the IMU but after reading the nRF54 datasheet I have found out (to my understanding) that I can instead feed a single 32.768 kHz crystal into the nRF54L15, use the GRTC to route that LFCLK out on a GPIO, and drive the IMU’s CLKIN pin with it—so both chips share the same reference clock?
If so, what configuration steps or caveats should I watch out for on the nRF54L15 side?

  • Hello Sindri
    Table 18 in 0.9 datasheet:
    Availability of GRTC.LFLPRC only in SystemOn would be the only thing I would be concerned about. Well, if you switch off the LFSRC you will kill the IMU as well of course. So make sure that IMU is ok with losing or to be halted if for some reason you need to switch LFSRC off.
    Best regards
    Asbjørn
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