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Uwe Bonnes
Uwe Bonnes
Chief
August 5, 2018
Question

STM32H7 and SYSCFG_UR2/3 register

  • August 5, 2018
  • 2 replies
  • 663 views

RM0433 is very short about the SYSCFG_UR registers. Most URx registers are read-only and probably provides another view at the values of the options byte. The reason to provide another view is not clear to me. However UR2 (BOOT_ADDR0) and UR3 (BOOT_ADDR1) are read/write and imply that they have influence on the boot process. Are these registers perhaps only reset by power-on reset? Or is the read/write tagging an error?

Please clarify.

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    2 replies

    Tesla DeLorean
    Tesla DeLorean
    Guru
    August 5, 2018

    Well the register file can function at 400 MHz, the options bytes probably cannot. The presumption would be at start-up some state-machine or other busing loads the SYSCFG side copies, and then SCB->VTOR gets loaded based on the BOOT pin, before execution starts.

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    Uwe Bonnes
    Uwe BonnesAuthor
    Chief
    August 6, 2018

    The option byte are already accessible in the Flash register file. So no obvious need to make them accessible one more time in the SYSCFG register file.

    But the read/write option of BOOT_ADDR0 and BOOT_ADDR1 is much more interesting. Clarification (and not guessing) is welcome.

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