4 Replies Latest reply on Nov 19, 2019 11:53 PM by SudheeshK_26

    S29GL256S90TFI020:Questions about flash ROM access




      An attempt was made to check the device ID on a board equipped with S29GL512T10TFI020 and S29GL256S90TFI020.
      However, S29GL256S90TFI020 results in a status error (code: 97).
      S29GL512T10TFI020 can read the device ID.


      After that, the device ID of S29GL256S90TFI020 can be read by inputting the CFI Enter command before read the device ID.


      Is the status mode undefined when the flash ROM is started?

      I want to find out why S29GL256S90TFI020 has an error and S29GL512T10TFI020 has no error.


      When confirming the device ID, must I perform CFI Enter-> Read ID-> Reset?



        • 1. Re: S29GL256S90TFI020:Questions about flash ROM access

          Hi Sawai-san,


          Could you kindly show your command sequence here, so that we could clarify what happened?


          Best regards,


          • 2. Re: S29GL256S90TFI020:Questions about flash ROM access

            Hi Sawai-san,


            I am not exactly sure what happened for your case, but for your questions, please see the following comments.


            For Q1, the device should be in read mode during power-on.


            For Q2, you are right.

            There are two methods to identify the device. One has traditionally been called Autoselect and is now referred to as Device Identification (ID). The other method is called Common Flash Interface (CFI).

            When reading the device ID, the sequence should be:

            1. ID (Autoselect) Entry or CFI Enter

            2. Read ID

            3. Reset/ASO Exit


            Are you waiting tVCS time after VCC crosses VCC(min) voltage before reading device ID from S29GL256S90TFI020? Please see the below screenshot from GL-S datasheet:


            • 3. Re: S29GL256S90TFI020:Questions about flash ROM access

              Hi Shuping-san,


              I'm sorry that it took time to confirm the command sequence.
              Below is the actual command sequence.


                    【Before entering CFI Enter】(status error (code: 97))
                 1)Addr 555 Data AA
                 2)Addr 2AA Data 55
                 3)Addr 555 Data 90
                 4-1)Addr 00  Read 0001(S29GL512T10TFI020)
                 4-2)Addr 00  Read 0097(S29GL256S90TFI020)
                 5-1)Addr 01  Read 227e(S29GL512T10TFI020)
                 5-2)Addr 01  Read 0088(S29GL256S90TFI020)
                 6-1)Addr 0E  Read 2223(S29GL512T10TFI020)
                 6-2)Addr 0E  Read 0088(S29GL256S90TFI020)
                 7-1)Addr 0F  Read 2201(S29GL512T10TFI020)
                 7-2)Addr 0F  Read 0088(S29GL256S90TFI020)
                 8)Addr 555 Data F0


                 【After entering CFI Enter】
                 1)Addr 55  Data 98
                 2)Addr 555 Data AA
                 3)Addr 2AA Data 55
                 4)Addr 555 Data 90
                 5-1)Addr 00  Read 0001(S29GL512T10TFI020)
                 5-2)Addr 00  Read 0001(S29GL256S90TFI020)
                 6-1)Addr 01  Read 227e(S29GL512T10TFI020)
                 6-2)Addr 01  Read 227e(S29GL256S90TFI020)
                 7-1)Addr 0E  Read 2223(S29GL512T10TFI020)
                 7-2)Addr 0E  Read 2222(S29GL256S90TFI020)
                 8-1)Addr 0F  Read 2201(S29GL512T10TFI020)
                 8-2)Addr 0F  Read 2201(S29GL256S90TFI020)
                 9)Addr 555 Data F0


              Addr 555 Data AA (ID (Autoselect) Entry) is performed in the sequence before entering CFI Enter, but status error has occurred.

              What are the possible factors?



              • 4. Re: S29GL256S90TFI020:Questions about flash ROM access



                You should be able to read device ID from both of GL-S and GL-T devices without entering CFI mode. Can you check if the tVCS time is meet in your application? Please make sure that you are waiting for at least tVCS time after VCC cross VCCmin to read device ID.


                Thanks and Regards,