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winIDEA shows question marks in the Memory Window

04-Feb-2022

winIDEA shows question marks "??" in the Memory Window whenever memory read at specific memory location fails.


Possible reasons:

  • No physical memory present at specific memory.
  • Debug interface memory read command fails for some reason.
  • Memory is not accessible after microcontroller power-on-reset and has to be configured first to become accessible respectively visible to the debugger (e.g., ECC protected memory, NOR flash external memory connected to dedicated Chip-Select signals, SPI flash, …).
  • When debugger reads erased flash cells, which keep random value after being erased. Such internal flash behavior can be found on Renesas RH850 and Infineon Traveo T2G.
  • Flash and RAM are ECC protected. Before you can read from flash location it must be erased and initialized (set to default value). By doing this ECC is cleared.
  • Debug interface memory read command fails for some reason.


More resources:

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