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Thread: Help with 12V to 5V step down converter.

  1. #31
    Maximum Bitrate Mickz's Avatar
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    Don’t all MB’s leave +5v standby running to all USB devices in sleep mode? Sleep is an instant on mode and everything had to be in exactly the same state as when the PC went into that mode AND it has to be in that same state almost instantly (unlike Hibernate).

    You can get away with removing or powering down a USB devise or two, sometimes, but it depends on what state the PC software and drivers were in with respect to the removed USB device access.

    You power down a hub after sleep and IMHO it’s unlikely the PC will resume, or it may even power up again, depends on HW, SW and the state of the PC at sleep.
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  2. #32
    Who am I? HiJackZX1's Avatar
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    Quote Originally Posted by Mickz View Post
    Don’t all MB’s leave +5v standby running to all USB devices in sleep mode? Sleep is an instant on mode and everything had to be in exactly the same state as when the PC went into that mode AND it has to be in that same state almost instantly (unlike Hibernate).

    You can get away with removing or powering down a USB devise or two, sometimes, but it depends on what state the PC software and drivers were in with respect to the removed USB device access.

    You power down a hub after sleep and IMHO it’s unlikely the PC will resume, or it may even power up again, depends on HW, SW and the state of the PC at sleep.
    Well my logic is that when the system sleeps, it monitors the last state, then when power on, it makes sure those devices are still present. Could I be wrong? When the PC wakes up all the devices should be active again.

    Im going to have to test this a bit, cant really do it though till the rig is in the car.
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  3. #33
    Low Bitrate Zephrant's Avatar
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    Quote Originally Posted by Mickz View Post
    Don’t all MB’s leave +5v standby running to all USB devices in sleep mode?
    Unknown, but from my experiments I can unpower my USB hub, then power it back up manually and the system returns from sleep just fine. That was with five devices on the hub.

    That was just on the bench for 7-8 tries in a row, I'll see how it goes once it is in the car. A second night I was trying the same the CPU kept waking up when I unplugged the hub. I'll need to try it with the cut power wire to the hub next.
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  4. #34
    Who am I? HiJackZX1's Avatar
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    Quote Originally Posted by Zephrant View Post
    Unknown, but from my experiments I can unpower my USB hub, then power it back up manually and the system returns from sleep just fine. That was with five devices on the hub.

    That was just on the bench for 7-8 tries in a row, I'll see how it goes once it is in the car. A second night I was trying the same the CPU kept waking up when I unplugged the hub. I'll need to try it with the cut power wire to the hub next.
    I did similar tests and the system came back on with no issue. Mind you not all devices and hubs were connected because a lot of stuff is hard wired into the car. I hope it works fine because I notice for experience, that on a bench the PC will behave different then when in the car. So im crossing my fingers. All I do know is that I am very happy with the 12V to 5V step down.
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  5. #35
    Maximum Bitrate Mickz's Avatar
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    Like I said, it depends on the state of the System at the moment of suspend.

    No, the PC does not reinitialise anything on resume from sleep. It continues on as though nothing had happened.

    Try unplugging the hubs while all USB communications and FE software are running and see what happens. If nothing hangs and you get no errors your good to go.

    Now, if you can power down all Hubs and devices and repower them before resuming from sleep AND providing all USB devices are initialised at power up to exactly the same state as the device driver had them prior to suspend then it can work, that a lot of if’s and that’s providing the PC does not randomly boot as some Hubs are powered down.

    If you want all devices to be reinitialised at start-up then use hibernate, that’s what it’s for.
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