Hard Processor System Technical Reference Manual: Agilex™ 5 SoCs

ID 814346
Date 4/01/2024
Public

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8.6.2.1. POR De-assertion Sequence

The reset manager supports power-on-reset (POR) as described below:

  1. The raw POR reset signal (sdm_to_aps_por_rst_n) comes through the PSI link from the SDM. This signal is de-asserted by the SDM based on different power and/or security conditions.
  2. The serial controller reset could get a reset from secure manager register.
  3. Once power is established and stable, and the raw POR reset signal (sdm_to_aps_por_rst_n) is stable, the reset manager is released from POR and the clock manager is released from POR.
  4. In the clock manager, the HPS internal oscillator starts toggling.
  5. A 16-stage reset synchronizer with the raw HPS oscillator clock synchronously releases pre_por_rst_n. In the clock manager, the boot_clk is taken out of reset. The boot_clk starts toggling, and all the clocks in the HPS are now active.
  6. The main reset controller in reset manager becomes active. Wait for 256 internal osc clocks and release por_rst_n and serial_ctrl_rst_n (the only SYSCFG reset driven from the reset manager).
  7. In the clock manager, the SYSCFG/SYSCFG COLD reset groups wait for at least 16 clock cycles to come out of reset as soon as por_rst_n is de-asserted.
  8. SDM can now access the shared and secure modules in the system configuration (SYSCFG) subsystem.
  9. The reset manager waits 128 clocks (POR release only).
  10. The SDM negates the cold/warm reset requests (if not already done).
  11. Go to reset de-assertion sequence (described in detail in the following section).