2 Replies Latest reply on Jan 3, 2018 3:52 AM by qh.zhao_2914506

    S25FL256S flash seems to be locked




      During development the Uboot/Linux driver for S25FL256S flash, I encounter a problem that the flash seems to be locked and cannot be reset. Even the JTAG also cannot erase/program the flash, only debug the code in the RAM.  


      I tried to read registers, the SR1 = 0x1C, the CR1 = 0xEE. the BPNV bit has been set to 1 and BP2-0 in SR are volatile and will be reset to binary 111 after POR. 


      How can I unlock the flash?

        • 1. Re: S25FL256S flash seems to be locked



          Did you try to change the value in SR1 and CR1 using WREN and WRR commands?


          1. CS# LOW


          2. WREN command


          3. CS# HIGH


          4. CS# LOW


          5. WRR command + SR1 value + CR1 value


          6. CS# HIGH


          Also, please let us know the steps you follow to program and erase flash device.


          Thanks and Regards,



          • 2. Re: S25FL256S flash seems to be locked

            I have got the similiar problem. I tried to change the CR1 value.And after that ,the flash device is unaccessible.I can not even read the device ID. The SR1 and CR1 value can not be read out either. Any idea will be appraciate.