Path: ...!weretis.net!feeder9.news.weretis.net!feeder8.news.weretis.net!newsfeed.xs3.de!nntp-feed.chiark.greenend.org.uk!ewrotcd!.POSTED.chiark.greenend.org.uk!not-for-mail From: Theo Newsgroups: comp.mobile.android Subject: Re: is my phone ON or is it OFF? Date: 27 Apr 2024 10:16:52 +0100 (BST) Organization: University of Cambridge, England Message-ID: References: Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Injection-Info: chiark.greenend.org.uk; posting-host="chiark.greenend.org.uk:212.13.197.229"; logging-data="5870"; mail-complaints-to="abuse@chiark.greenend.org.uk" User-Agent: tin/1.8.3-20070201 ("Scotasay") (UNIX) (Linux/5.10.0-22-amd64 (x86_64)) Originator: theom@chiark.greenend.org.uk ([212.13.197.229]) Bytes: 3251 Lines: 42 Jörg Lorenz wrote: > On 25.04.24 15:55, Frank Slootweg wrote: > > Jeff Layman wrote: > > [...] > > > >> The charging circuitry is within the battery itself. It controls the > >> rate of charge and, in particular, monitors the temperature of the > >> cell(s). If it gets too high it will stop the charging. Note though, > >> that the connection from the phone's charger socket (lightning, USB, or > >> whatever) goes through some of the phone's circuitry, so the phone knows > >> the state of charge of its battery. That way its % charge can be > >> displayed on the phone's screen, and battery-usage apps can let you know > >> what's being used and how long the phone might last before recharging is > >> essential. > > > > The fact that the phone is charging and how full its battery is, is > > also displayed/displayable when the phone is switched 'off'. > > > > Ergo, the phone is never really off. It's either awake or sleeping > > during normal use or in cold standby when the user switched it 'off'. > > Bullshit! > The OS is not booted when the Android is turned off. AIUI it is, kind of. When you plug in the charger with the phone off, the phone starts. The bootloader then launches the Android kernel with the flag androidboot.mode=charger Instead of doing the full Android boot, that causes the kernel to launch a charger UI application that shows your battery percentage on the screen or an animation (which comes from files on your OS partition). The charger app doesn't allow you to otherwise interact with the phone and other services like the radios aren't running, but the SoC is booted and running software. The SoC is also doing standard power management, ie the charging process here likely looks very similar to charging when the phone is turned on (because it is, in essence). The full OS services are not running, but the Android kernel and the charger app is. Theo (usual caveats: my understanding may be out of date, different vendors may do their own thing, etc)