4 Replies Latest reply on Apr 26, 2016 3:18 AM by davide.bozzato

    L2 suspend

    davide.bozzato

      Hi all,

         

      dealing with FX3S power management I see on its manual (CYUSB303X_001-84160_0D_V.pdf,  page 13) an interesting suspend mode: "
      Suspend mode with USB 3.0 PHY disabled (L2)". The strange thing is that "Methods of Exit" is equal to L1, where the PHY is enabled.

         

      1 - How can the cpu be re-woken from USB bus if the PHY disabled?

         

      2 - Is it possible to enter in L2 suspend mode using the API? this can be very useful to save some mW and reach the (in)famous 2.5mA total suspend current...

         

      Thanks

         

      Dax

        • 1. Re: L2 suspend
          Madhu Lakshmipathy

          Hi,

             

          Only the USB 3,0 Phy is disabled. The USB 2.0 Phy will still be active and can be used for wakeup. Yes the CyU3PSysEnterStandbyMode Api can be used to bring the device to this mode and achieve the specified current.

             

          Regards,

             

          -Madhu

          • 2. Re: L2 suspend
            Madhu Lakshmipathy

            Typo CyU3PEnterStandByMode mode API

            • 3. Re: L2 suspend
              davide.bozzato

              Hi, thanks for your reply.

                 

              Maybe the typo was the 2nd function name because into API documentation I can only find the 1st function name (CyU3PSysEnterStandbyMode). Anyway CyU3PSysEnterStandbyMode requires the shutting down of all block except GPIO. This function seems suitable for a self-powered application, not a bus-powered as in our project.

                 

              The right function seems to be CyU3PSysEnterSuspendMode, where the CY_U3P_SYS_USB_WAKEUP_SRC_EN can be used. In this case i tried to use CyU3PConnectState to power off the phy, as suggested by documentation, but the subsequent call to CyU3PSysEnterSuspendMode returns CY_U3P_ERROR_BAD_ARGUMENT and the device re-enumerates.

                 

              Is there a specific sequence to enter L2 suspend mode with USB activity as wakeup source?

                 

              Thanks

                 

              Dax

              • 4. Re: L2 suspend
                davide.bozzato

                Hello? is there somebody in? ;-)