Zynq UltraScale+ Device Technical Reference Manual (UG1085)

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2.4 English

In this example, the PS_SRST_B reset input is held Low (asserted) while PS_POR_B is deasserted and the CSU executes its ROM code. The CSU continues to execute the ROM code (regardless of the PS_SRST_B state) until the CSU can verify if the boot is secure or non-secure by reading the boot header. For non-secure boot and PS_SRTS_B asserted, the CSU execution halts when it enables the PS_SRST_B input. For secure boot and PS_SRST_B asserted, the CSU continues to execute and the FSBL is loaded into memory because the PS_SRST_B pin remains disabled.