iPhones are allergic to helium

Re:iPhones are allergic to helium by analog31 on Tuesday October 30, 2018 @11:38PM (#18343156)

Indeed, and historically, a slower RTC clock was also preferred because it would draw a lot less current during sleep mode. And it allows the rest of the system to throttle the main system clock up and down for power savings.

I said "historically" because I don't know is if these are still important issues on a modern system relative to all of the other things that are probably using the main system clock during sleep mode, and the more generous battery.

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Re:iPhones are allergic to helium by dbcurtis on Wednesday October 31, 2018 @12:48AM (#18343438)

Clock throttling is still a thing. Many ARM Cortex-Mx parts, when in deep sleep, draw less current than the self-discharge rate of a standard alkaline battery sitting on a store shelf waiting to be purchased. It is common to leave the RTC running, stash important data in the small RAM that is backed up by a super-cap, and go into a “wait for interrupt” deep sleep mode.

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Re:iPhones are allergic to helium by hazeii on Wednesday October 31, 2018 @01:23PM (#18347592)

In the embedded world this is very standard; timed wake-up from sleep is driven by the 32.768KHz clock, the code then wakes up faster clocks/peripherals as required by the application.

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