Some mobile phones have the option to schedule switch-off time and switch-on time. Switch-off time is understandable. But how can a mobile switch itself on, if it was completely switched off?
Does this imply that, even when the mobile is switched off, the screen is off and the hardware buttons are not responsive, the mobile is never really switched off?
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>Does this imply that, even when the mobile is switched off, the screen is off and the hardware buttons are not responsive, the mobile is never really switched off?
Correct. “off” for phones is more about stopping the sending/receiving of signals and stopping as much computation as possible. Some computing will still be needed. That’s why for most electronics, not just mobile phones, they have a small battery that keeps the internals running so things like the clock won’t need to be reset every time it’s turned off and on.
A similar thing would be phone’s that ‘aren’t listening to you’ but will respond when you say something like “hey Siri”. What it actually means is that they are listening to you but only listening for that phrase.
>Does this imply that, even when the mobile is switched off, the screen is off and the hardware buttons are not responsive, the mobile is never really switched off?
Correct. “off” for phones is more about stopping the sending/receiving of signals and stopping as much computation as possible. Some computing will still be needed. That’s why for most electronics, not just mobile phones, they have a small battery that keeps the internals running so things like the clock won’t need to be reset every time it’s turned off and on.
A similar thing would be phone’s that ‘aren’t listening to you’ but will respond when you say something like “hey Siri”. What it actually means is that they are listening to you but only listening for that phrase.
It is correct that the mobile is never really switched off. You can turn off most components, including the radio and main processor. But there is always a tiny clock running in the mobile phone. It is a tiny part of the circuitry without many functions. But it can be programmed to turn on the rest of the phone at a certain time. Or it can measure how long you hold down the power button and turn on the rest of the phone this way. And when the phone starts up it can tell the phone what the time is as it have kept track all the time.
It is correct that the mobile is never really switched off. You can turn off most components, including the radio and main processor. But there is always a tiny clock running in the mobile phone. It is a tiny part of the circuitry without many functions. But it can be programmed to turn on the rest of the phone at a certain time. Or it can measure how long you hold down the power button and turn on the rest of the phone this way. And when the phone starts up it can tell the phone what the time is as it have kept track all the time.
It is correct that the mobile is never really switched off. You can turn off most components, including the radio and main processor. But there is always a tiny clock running in the mobile phone. It is a tiny part of the circuitry without many functions. But it can be programmed to turn on the rest of the phone at a certain time. Or it can measure how long you hold down the power button and turn on the rest of the phone this way. And when the phone starts up it can tell the phone what the time is as it have kept track all the time.
They are never truly off, as long as any source of power is connected. Rather than switching off, they switch to so-called low power state, where most peripherials are switched off, the CPU is powered but basically performs no or very little operations and the Real-Time Clock chip sends a signal to “wake it up”.
They are never truly off, as long as any source of power is connected. Rather than switching off, they switch to so-called low power state, where most peripherials are switched off, the CPU is powered but basically performs no or very little operations and the Real-Time Clock chip sends a signal to “wake it up”.
They are never truly off, as long as any source of power is connected. Rather than switching off, they switch to so-called low power state, where most peripherials are switched off, the CPU is powered but basically performs no or very little operations and the Real-Time Clock chip sends a signal to “wake it up”.
>Does this imply that, even when the mobile is switched off, the screen is off and the hardware buttons are not responsive, the mobile is never really switched off?
Correct. “off” for phones is more about stopping the sending/receiving of signals and stopping as much computation as possible. Some computing will still be needed. That’s why for most electronics, not just mobile phones, they have a small battery that keeps the internals running so things like the clock won’t need to be reset every time it’s turned off and on.
A similar thing would be phone’s that ‘aren’t listening to you’ but will respond when you say something like “hey Siri”. What it actually means is that they are listening to you but only listening for that phrase.
> Does this imply that, even when the mobile is switched off, the screen is off and the hardware buttons are not responsive, the mobile is never really switched off?
Power management has actually gotten pretty complex. The following would be typical states that a modern smartphone might be in:
– **High performance**: the OS detected that some app is using a lot of processing power, so briefly boosts the CPU speed to help it. It can’t do this for too long because of power consumption and heat dissipation reasons.
– **Regular performance, fully on**: the normal state when the user is on the phone.
– **Idle**: user hasn’t touched it for a while, so let’s dim the screen and wait a bit longer.
– **Sleep/locked**: turn off the screen and power down the main CPU, leaving the baseband processor to periodically talk to the cellular network, and maybe a specialized low-power chip to listen for things like “Hey, Siri.”
– **Low power**: running low on battery, pause the routine maintenance tasks, cap CPU performance. Warn the user!
– **Charging overnight**: the user is probably sleeping, let’s take this time to do housekeeping tasks and maybe even download a software update or two.
– **Off**: everything off except minimal circuitry that can turn things back on if the user presses the power button.
So it really depends on the specific software design, but there generally is a “pretty-close-to-truly-off” state that uses very little power, even though phones don’t typically have a physical circuit-breaking switch that disconnects it from the battery.
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