1.6 Reset

For designing a robust system, users may use the dedicated DEVRST_N pin or a general purpose reset signal using any GPIO/HSIO as a global system level reset.

For the following cases, the users must use the DEVRST_N as a warm reset for the device:

  • A user design modifies auto-initialized fabric RAMs or PCIe configuration during operation.
  • A user design is using PCIe, transceivers or user crypto.

    For all other use cases, it is recommended to use a general purpose reset signal using any GPIO/HSIO IO because they take much shorter time for design to come out of reset.

    If the dedicated DEVRST_N is not used for warm resets, the DEVRST_N pin must be configured using one of the following methods:

  • Drive the signal with a POR chip or an external device and keep the DEVRST_N asserted till the system/clocks are stable and the chip is properly powered up.
  • Connect DEVRST_N to VDDI3 through a 1 kΩ resistor per pin without sharing with any other pins.
    • In this case, the user needs to ensure that all clocks are stable going to the device before the user design is released from power-on reset. The details of the minimum time taken for the fabric design to be activated after power-on is specified in the Power-Up To Functional section of PolarFire SoC Datasheet.