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Author Topic: How can we ensure device not suspend in MSD?  (Read 13870 times)

eng.Buffon

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How can we ensure device not suspend in MSD?
« on: March 03, 2012, 06:27:38 am »
hi guys

hi everyone,

i wanna know how to ensure that my device of Mass Storage Class don't suspend , when there is no transaction on the bus?

as in HID there was periodically IN Transaction so the device can't suspend>>

please help me

thanks in Advance
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Pat Crowe

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Re: How can we ensure device not suspend in MSD?
« Reply #1 on: March 03, 2012, 10:45:22 am »
Suspend is a state which the host may require at any time. A device is required to respond appropriately, and reduce its current draw to 2.5mA. This applies equally to any device regardless of class. There is nothing that a device, on its own, can do to avoid this. Some operating systems may have settings to make suspend less likely.
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eng.Buffon

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Re: How can we ensure device not suspend in MSD?
« Reply #2 on: March 04, 2012, 03:08:57 pm »
what about keep-alive message?
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Pat Crowe

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Re: How can we ensure device not suspend in MSD?
« Reply #3 on: March 04, 2012, 03:49:09 pm »
I could say 'what about it?'.  :)

Keep Alive is the low speed equivalent of the Start of Frame packet. Both KeepAlive and SOF are used by the host to (among other things) tell the device not to suspend at the moment.

The point is that it is the host that decides - not the device.
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