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Any Known Issues With Suspend/Resume and VLPS With KL26

Question asked by Chuck Horkin on Mar 24, 2016
Latest reply on Mar 30, 2016 by jeremyzhou

Hello,

 

I have code that puts my device to VLPS when the SLEEP bit is set (due to a suspend) on the USB bus.  I'm using the Freescale USB Stack v4.1.1.  I monitor USB_USBTRC0_USBRESMEN_MASK to see if I can enter VLPS and then I do.


This works in most cases, but I'm finding on some platforms with some corner cases it does not.  I've more or less

proven that I get stuck in the VLPS state instead of asynchronously resuming.

 

When I get stuck I'm seeing that my Clear Feature Remote Wakeup is getting Stalled as Well.

 

Is there any known issues with this or known limitations with certain systems?

 

Is there a suggested approach for power management with the USB stack?

 

Thanks.

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