Cyclone® V Hard Processor System Technical Reference Manual

ID 683126
Date 8/28/2023
Public
Document Table of Contents

5.3.5. Boot Handshake

There are two input signals from the FPGA to control HPS boot from the FPGA. Both are synchronized within the FPGA Manager. Boot software reads these signals before accessing a boot image in the FPGA. The following table describes the functionality of these signals.

Signal Description
f2h_boot_from_fpga_on_failure

Indicates whether a fallback preloader image is available in the FPGA on-chip RAM at memory location 0x0. The fallback preloader image is used only if the HPS boot ROM does not find a valid preloader image in the selected flash memory device. It is an active high signal which the bootrom polls when all the preloaders fail to load. This signal is driven low when the FPGA is not configured and it is up to you to drive it high in your user design.

f2h_boot_from_fpga_ready

Indicates a preloader image is available in an FPGA on-chip RAM at memory location 0x0 and it is ready to be accessed. It is an active high signal which the bootrom polls to determine when the FPGA is configured and the memory located at offset 0x0 from the F2H bridge is ready to be written to. When the FPGA is not configured the hardware drives this signal low and it is up to you to drive it high when the memory in the FPGA is ready to accept memory mapped transactions.