RTC battery

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Joined: Tue Jan 08, 2019 1:16 pm
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RTC battery

Post by vsavu » Thu Jan 10, 2019 8:46 am

The system detects the RTC in the system, but the time is invalid.

Code: Select all

[    5.022527] drivers/rtc/hctosys.c: unable to open rtc device (rtc0)
[    9.072497] rtc-st-sbc rtc_sbc.57: rtc core: registered rtc-st-sbc as rtc0
[    9.072611] rtc-st-sbc rtc_sbc.57: Setting system clock to 1999-11-30 00:00:00 UTC
Is it possible to connect a battery to power the RTC while power is disconnected?

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Re: RTC battery

Post by nick.beck » Fri Jan 11, 2019 11:41 am


There is a real-time clock within the standby controller (SBC), but the RTC is not battery backed, so would need to be set each time the board is power-cycled.

We might be able to provide a more useful answer if we understand your product use-case better. For example, does the device have an internet connection? If so it may be possible to set the time using NTP.

The SBC allows the SoC to only draw 30mW when in controller passive standby mode, so it may be feasible for you to keep this powered at all times and therefore maintain a good RTC clock valye, but the rest of the SoC disabled. Without knowing more about your system/use-case it is hard to say.

If you would like to discuss this in more detail privately then please let me know

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