I have a STM32WB55 custom board where I put the Read out Protection to level 1. I would like to change it back to level 0 as in this level, I am unable to program the PCB. I have tried using the ST LINK utility and the STM32Prog to change it back to level 0 but to no avail

STLINK Utility:

 Could not set Option bytes! 
    Please reset the target and retry. 
    Can not read memory! 
    Disable Read Out Protection and retry.

STM32 Prog :

Error: Expected value for Option Byte "RDP": 0xAA, found: 0xFF
Error: Option Byte Programming failed

From what I read online if my version of STLINK utility is higher than 4.0 it will work but it is not the case. Boot0 is at high and I have try reseting it but to no avail as well. Any ideas on how I can change it back?

  • 2
    \$\begingroup\$ Generally with erasing the entire chip \$\endgroup\$
    – uglyoldbob
    Jul 9, 2020 at 15:44
  • \$\begingroup\$ @uglyoldbob full chip erase works? \$\endgroup\$
    – jellybean
    Jul 9, 2020 at 15:45
  • \$\begingroup\$ why don't you try? \$\endgroup\$
    – muyustan
    Jul 9, 2020 at 15:49
  • \$\begingroup\$ @muyustan ive just tried and I cant as the read out protection prevents it \$\endgroup\$
    – jellybean
    Jul 9, 2020 at 15:50
  • \$\begingroup\$ Disabling readout protection does a full chip erase. But then you must FULLY POWER CYCLE THE BOARD before it takes effect. To make sure it's not still getting current leakage, disconnect everything - SWD, serial, USB, there should be no wires connected to the target at all. \$\endgroup\$ Jul 9, 2020 at 16:13

1 Answer 1


open ST-LINK utility-> go to Target -> Option Bytes then change the Read Out protection to level 0 Apply, then make a full chip erase. it has worked for me, hope this helps you

I found the answer in this link https://community.arm.com/developer/tools-software/tools/f/keil-forum/34824/can-t-disable-read-out-protection


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