6 Replies Latest reply on Jul 6, 2020 5:45 AM by YaAd_4714631

    CYUSB3014 Enumeration issue

    YaAd_4714631

      Dear Cypress community,

      I am writing this post as I have a nasty issue with one of the boards, I have designed using the CYUSB3014.

      I have designed 3 boards before that one using the same chip and never had such a problem.

      I ordered for PCB manufacturing 10 prototypes of the new board. All the boards came with a problem on the CYUSB3014.

      This the description of my observation the schematic is given below:

      1- Half of the boards do not enumerate at all

      2- The other half enumerates after applying a small pressure around pin 1

      3- In the faulty half There is no traffic detected on the USB 2 port when probing it with a scope

      4-Some in the faulty half have the 19.2 MHz oscillator not working but it start working when pressing the reset button but no enumeration is observed even after pressing the reset.

      5- Some of the other faulty ones never have the oscillator working at all

      6- The "good half" work after applying a slight pressure around pin 1 area and the chip enumerates. It was observed that the oscillator is not running before applying the pressure.

      7- When releasing the pressure on the chip may or may not stay connected.

      8- The power voltage noise is below 5mV

       

      I am very aware that is likely to be a signal integrity problem but what I am expecting from the community is to point me to  a way to find the root cause of this problem.

      I would like to understand what is preventing the oscillator from oscillating?

      Why In certain cases the oscillator kicks in when keep the reset pressed then shuts down when releasing the reset?

      Why there is no traffic observed on the USB2.0 bus when connecting the chip to a host?

      Please point me to tools that I could use to trouble shoot my boards (e. JTAG, UART, ..)

       

        • 1. Re: CYUSB3014 Enumeration issue
          RashiV_61

          Hello,

           

          Please refer to the hardware guidelines mentioned in application note  AN70707 https://www.cypress.com/file/139936/download

           

          - We have seen similar enumeration/boot fail / no USB 2.0 activity (when the device is used in USB 2.0) previously. There is a possibility that this issue occurs due to the oscillator problem.

          -  In your observation, when the pressure is applied the oscillator starts oscillating and then the enumeration starts. It seems that as the oscillator is not oscillating the enumeration fails.

          - Please confirm that the crystal used in the design meets the specification mentioned in AN70707 (section 5.1). If possible you can try using the same crystal part as mentioned in the application note.

          - As the power domain of the XTALIN (C6) and XTALOUT (C7) is AVDD. Please confirm that the 1P2V power domain is stable.

           

          Please refer to Superspeed Explorer kit schematics https://www.cypress.com/documentation/development-kitsboards/cyusb3kit-003-ez-usb-fx3-superspeed-explorer-kit

           

          Please let me know the status of the PMODE lines and whether the device is plugged to USB 2.0 or USB 3.0 port?

           

          Regards,

          Rashi

          • 2. Re: CYUSB3014 Enumeration issue
            YaAd_4714631

            Hi Rashi,

            I would have loved to know the problem is from the oscillator choice but it does not look like it is the case.

            There was a resent poste with a similar issue CYUSB3014 boot issue but there was no conclusion to the case (use google translate ).

            I have previously designed 3 other versions of and CYUSB3014 but I did not observe such a behaviour.

            This is the oscillator that was used 405C35B19M20000 CTS-Frequency Controls | Crystals, Oscillators, Resonators | DigiKey  It is meeting the requirement of AN70707 and was used in the previous working designs.

            If was to criticise my design I would say maybe I did not follow accurately the recommendation about the diff pairs but I wouldn't see why it would be a problem at such a small distance from the connector, about 40mm.

            1- I did not put a clearance under the ac coupling capacitors.

            2- The diff pairs are estimated to be 105 Ohm instead of 90 Ohms

            3- Gnd via was not added next to signal via as in Fig 21.

            The status of PMOD is X1X (I2C then USB) but have changed it to X11 (USB only) but have not seen any change.

            The device is plugged to USB 3.0 capable port, but I was monitoring the traffic using the scop on USB 2.0. I don’t have a scope that is fast enough to monitor the traffic on the USB 3.0.

            The power 1V2 and 3V3 was monitored and appears to be stable and less than 5mV of noise.

            Do you have an explanation why the crystal works when pressing the reset switch (S2 on the schematic) for some boards? (This is really blowing my mind).

            Can you tell me that pin specifically supplies the 1V2 to the oscillator?

            Thanks,

            Yacine

            • 3. Re: CYUSB3014 Enumeration issue
              RashiV_61

              Hello Yacine,

               

              Is it possible for you to share the full schematics of the FX3 part for us to review and narrow down the problem?

              Also, what are the changes that are done in the design of board in comparison to the boards which were working

              - do you see any activity on USB 2.0 lines? This is the expected activity on USB 2.0 lines when the devices plugged in USB Made Simple - Part 6 . IS it possible for you to compare this with your design and let me know the results

               

              Regards,

              Rashi

              • 4. Re: CYUSB3014 Enumeration issue
                YaAd_4714631

                Hi Rashi,

                I am happy to do so but not publicly as it is a strategic commercial product that we are developing.

                Can we take this discussion off the records?

                I assume you have my email address in your system?

                Best regards.

                Yacine

                • 5. Re: CYUSB3014 Enumeration issue
                  RashiV_61

                  Hello Yacine,

                   

                  Please reply with the schematics to the mail that i have sent

                   

                  Regards,

                  Rashi

                  • 6. Re: CYUSB3014 Enumeration issue
                    YaAd_4714631

                    After failure analysis from Cypress :

                    In conclusion, the reported problem was confirmed. Both units failed due to cut stitch bonds caused by popcorn package delamination. This may not represent the original failure as failure may have been induced during the customer’s board mounting process. We recommend the customer to bake the parts prior board removal and to use a controlled heat source.