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Date of registration: Dec 11th 2015

Posts: 1


Monday, February 8th 2016, 11:19am

[SOLVED] Preventing J-Link to flash all the MCU flash pages while debugging

I am using J-Link to program and debug my MCU unit,
I want the last two pages of the STM32F334 MCU to be used for storing and updating users settings , they users can update and change the settings and the MCU should keep them when it is not powered.

For my debugging and testing purpose I am using J-link to test and debug the MCU code, and despite the fact that I implicitly mentioned in the linker file the code flash origin and its size as
rom (rx) : ORIGIN = 0x08000000, LENGTH = 0x0000f000 every time I debug with J-Link it will zeros and destroys those flash pages that are used for storing the user settings.

How can I implicitly (command line argument) prevent the J-Link to write over certain flash address [In my case Range:0x0800F000-0x0800FFFF --> Two 2K pages should not be altered by J-Link]

which option fields in the following eclipse J-Link debugger configuration should be modified.
Note: I can not write protect those flash pages since the MCU firmware must store the user's parameters in those pages during test+debug.
Thanks :(
si.s has attached the following images:
  • J-link_fp1.jpg
  • J-link_fp2.jpg


Super Moderator

Date of registration: Dec 18th 2007

Posts: 1,516


Tuesday, February 9th 2016, 9:04am


J-Link only touches the flash pages that are written by the debugger (here Eclipse + GDB).
If they are zeroed it means Eclipse is downloading zeroes to this region.
Sounds like your linker file is not correct.

You should specify the section as "NOLOAD" in your linker file if you do not want Eclipse / GDB to load it on debug session start:…node/ld_21.html

Best regards