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      • 15. Re: How can I wake BCM20737S up by using GPIO interrupt?

        Thank you so much, BrCa_1072751!

         

        I could solve this problem with USB disconnected!! I didn't notice the effect of USB to board.


        BrCa_1072751 and MichaelF_56 - By any chance, are there any other functions affected by USB? Do you know?

        If your answer is yes, please let me and other users know about all functions as far as you know in other threads.

         

        Anyway, thank you, BrCa_1072751!!

        • 16. Re: How can I wake BCM20737S up by using GPIO interrupt?
          MichaelF_56

          userc_16079 BrCa_1072751 userc_4183 ankr_1205151

           

          Here's the explanation for why unplugging the USB allows the device to appear to come out of Deep Sleep, when really something completely different occurs..

           

          Essentially, when coming out of Deep Sleep, or HIDOFF, the device reboots. When rebooting, the firmware knows to look at the HCI Rx line to see if its high, or if there is an external host attached.  When the USB cable is attached, the HCI UART Rx line is indeed high by design (handled by the FTDI bridge chip).

           

          Therefore, when plugged into USB, the firmware senses this HCI Rx high state, it puts the part into programming mode (or HCI mode as it is sometimes referred to in the documentation).

           

          So while it is not technically in Deep Sleep anymore, it appears that way.  In reality, the part is in programming mode.

           

          Unplugging the USB cable removes the external high signal on HCI Rx, hence when the part reboots coming out of deep sleep as directed by the application, it never goes into programming mode.

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