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winIDEA shows question marks in the Memory Window

09-May-2024

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


Possible reasons

  • No physical memory present at the specific memory.
  • The debug interface memory read command fails for some reason.
  • The memory is not accessible after the 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, etc.).
  • When the debugger reads the erased flash cells, which keep a random value after being erased. Such internal flash behavior can be found on the Renesas RH850 and Infineon Traveo T2G.
  • Flash and RAM are ECC protected. Before you can read from the flash location it must be erased and initialized (set to default value). By doing this the ECC is cleared.
  • The debug interface memory read command fails for some reason.


More resources


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