System Level Reset Requirements - 2020.2 English

Zynq UltraScale+ MPSoC Software Developer Guide (UG1137)

Document ID
UG1137
Release Date
2021-01-05
Version
2020.2 English

The system-level reset term is used to describe the system or subsystem level resets. ‘System’ reset (different from system-level resets) is a specific type of system-level reset. The following table provides summary of system-level resets, which are described in details in subsequent sections.

Table 1. System-Level Resets
Reset Type Description
External POR The external POR reset is triggered by external pin assertion. There are a number of software only registers which are not reset by the POR resets. At first POR boot, a safety system (requiring HFT1 by PS & PL) can be configured such that a subsequent POR only resets PS (and not PL).
Internal POR Internal POR reset can be triggered by software register write, or by safety errors. With the exception of error status register (which are reset by external POR, but not by internal POR), internal POR resets the same thing as external reset does. Internal-POR cannot be guaranteed without silicon validation (due to in-rush power concern), so internal-POR is for internal purpose unless validated.
System Reset System reset is to be able to reset system excluding debug logic. To simplify system reset, there are few other things (xBIST, scan clear, power gating) which are not reset by this reset. Also, boot mode information is not reset by system reset. The system reset can be triggered by external pin (SRST), or software register write, or by safety errors.
PS Only Reset The PS only reset is to reset the PS while the PL remains active. This reset can be triggered by hardware error signals or by software register write. This reset is a subset of system reset (excluding the PL reset). If the PS reset is triggered by an error signal, then the error is also transmitted to the PL.
FPD Reset The FPD reset resets all of the FPD power domain. It can be triggered by errors or software register write. If the FPD reset is triggered by an error signal, then the error is also transmitted to LPD & PL.
RPU Reset The RPU Reset is to reset the RPU in case of errors. While each of the R5 core can be independently reset, but in lockstep, only R5_0 needs to be reset to reset both the R5 cores. This reset can be triggered by errors or software register write.