5 Replies Latest reply on Jun 24, 2019 12:31 AM by BacemD_61

    S25FS512S spi not replying


      Hello, i have a board with some S25FS512S  chips on it that i try to access through the SPI, but they dont reply.


      I know i send the correct signals, because i send the same signals to a similar FLASH (S70FL01GS) and that one replies fine.


      I attach you a screenshot of the signals and from bottom to top they are:


      S25FS512S SO/IO1




      S70FL01GS SO/IO1


      The signals from the first flash that is fed from a 3.3V domain, pass through level shifters and they have the correct voltage at the end.

      i Use the following pin reference:


      Please also note that all RFU,NC,DNU,IO3,IO2 are left open.



      1.i notice that RESET# and WP# are stuck at 0 in both flash types. Should't they be put to 1 as they are unconnected?

      2.An important difference that i notice between the working and not working flashes is that in S70 while in standby SO is stuck at 1 while in the S25 is at 0. Is this important? What could this mean?


      P.S. the exact number at the top of the chip is : fs512sAIF01 84100025 B


      Thank you very much for you Help.

        • 1. Re: S25FS512S spi not replying



          Both RESET# and WP# pins have an internal pull up resistor and can be left unconnected, if not used.

          Are the SPI signals shared between the two flash devices (S70FL01GS and S25FS512S)? Could you please attach the schematic diagram of your application? Where did you probe to collect the attached scope shot? Is it on the pins of S25FS512S flash device?


          Thanks and Regards,




          • 2. Re: S25FS512S spi not replying

            Hello, and thank you for the reply.

            I attach you the schematic of the board where the S25FS512S are on.


            the MOSI and the SCLK are shared except of the level shifters in between.


            The bottom signal on the scope is probed on the S25FS512S MISO which is

            left open for the probing.

            the three middle are also probed on the pins of the S25FS512S

            The Top signal on the scope is probed on the S70FL01GS MISO, directly on

            the pin.




            • 3. Re: S25FS512S spi not replying



              I checked the schematic diagram that you attached. There are 6 S25FS512S flash devices present on your board. Are you facing this issue with all of them? Also, I did not see any S70FL01GS devices connected in the schematic diagram. Could you please clarify, how you probed both the devices at the same time?


              Thanks and Regards,


              • 4. Re: S25FS512S spi not replying


                yes, i face the same issue on all devices.

                The whole system is comprised of many boards,. i attach you now also the

                board of the level shifters and the board of the S70FL01GS that also

                contains an MCU. They are connected through the connectors.


                I notice that the MISO on the S70FL01GS starts from 1. Do i have to weak

                pull up the MISO?




                • 5. Re: S25FS512S spi not replying



                  You mentioned earlier that RESET# and WP# are stuck at 0. This should not be the case otherwise this would mean that the part is in continuous reset mode. Please double check!


                  Please also check your power supply and that you comply with the Power On reset specification from the datasheet, e.g: CS# should ramp up with VCC, VCC should not have power drops...

                  It looks like the S25FS512S units are not responding at all. Please check that their corresponding CS# signals are being driven properly and one device is selected at a time, because otherwise you get into bus contention.


                  Best regards,