RE: RTC0 as a real time clock on nRF9151?

Mich@l — Fri, 10 Oct 2025 11:09:32 GMT

Thanks for the response! Everything’s clear now.

RE: RTC0 as a real time clock on nRF9151?

tesc — Thu, 09 Oct 2025 10:15:22 GMT

Hi,

Please note that the RTC peripheral on the nRF9151 is a Real Time Counter, not a Real Time Clock. The counter is reset on reset, similar to other timer peripherals. There are in other words no tricks to keep the counter counting through a reset. In order to keep track of time, you would therefore either need to keep the device on, use an external real time clock, or poll the current time over a network connection or other source.

Depending on the type of reset, and depending on how accurate time tracking you need, it could be possible to keep the last known time in retained RAM, or written to Flash, to keep track of time through certain types of reset (but with some uncertainty depending on how frequently the time is stored and/or how long the device is not operating during the reset.) See reset behavior for what is retained and reset on various reset sources. Please note that the Flash on the nRF9151 is rated for 10 000 write/erase cycles, which means if storing time to flash you should do so in a manner which does not wear out Flash before the expected life time of your device.

Regards,
Terje