4 Replies Latest reply on Jan 15, 2017 6:18 PM by suhas.reddy

    Not able to read without power on reset in S25FL128S

    suhas.reddy

      Hi,

         

      I have implemented my design on an FPGA. I am trying to erase,write and read the SPI flash in the same order. I am able to erase and write properly but when i try to read soon after the write operation, it is showing all 1's. But if i give a power on reset to the flash and then read, it is showing the correct value which i wrote before. Please give some suggestions regarding this issue. 

        • 1. Re: Not able to read without power on reset in S25FL128S
          gsns

          Hello Suhas,

             

          Please specify which write and read operation you are performing. For example, Read ( 3 byte addressing or 4 byte addressing), Dual read or Quad read, Fast read etc.

             

          Also tell us the status register (SR1) values during both operations. Before power on reset and after.

             

          Are you sure that the timings are met ? what is the delay between write and read ? After power on are you reading directly or following the same sequence  erase,write and read.

             

          Thanks,

             

          Krishna.

          • 2. Re: Not able to read without power on reset in S25FL128S
            suhas.reddy

            Hi,

               

            Thanks for the reply. I am giving sector erase command (D8h,address 000000) followed by page program (02h,address 000000) which is 3 byte addressing and followed by read command (03h, address 000000).  Every operation is in SDR and single lane mode. Also before read i am giving software reset(F0h) and mode bit reset(FFh) commands followed by write register command(01h) where i am clearing the status register 1 (00h) and changing the contents of configuration register to C0h (Keeping latency code as 11). 

               

            Last i checked timings are fine and also there is sufficient delay after write before read command is given, the delay is more than 50s. After power on i am doing only read operation with all the other commands specified above which is F0,FF,01h (SR1-00h,CR-C0h). Status register 1 values after erase and write is 00h, but i didn't check after read operation.

               

            Regards,

               

            Suhas

            • 3. Re: Not able to read without power on reset in S25FL128S
              gsns

              Hello Suhas,

                 

              Can you please poll  the status register WIP bit. Also try changing the latency code ( other 11) and check if you are seeing the same issue.

                 

              Thanks,

                 

              Krishna.

              • 4. Re: Not able to read without power on reset in S25FL128S
                suhas.reddy

                Hi,

                   

                The issue is resolved, there was a problem with the boot code. Thank you for the guidance.

                   

                Regards,

                   

                Suhas