Virtual JTAG Intel® FPGA IP Core User Guide

ID 683705
Date 8/12/2021
Document Table of Contents

Issuing the HUB_INFO Instruction

The SLD hub contains the HUB IP Configuration Register and SLD_NODE_INFO register for each SLD node in the design. The HUB IP configuration register provides information needed to determine the dimensions of the USER1 DR chain.

The SLD_NODE_INFO register is used to determine the address mapping for Virtual JTAG instance in your design. This register set is shifted out by issuing the HUB_INFO instruction. Both the ADDR bits for the SLD hub and the HUB_INFO instruction is 0 × 0.

Because m and n are unknown at this point, the DR register (ADDR bits + VIR_VALUE) must be filled with zeros. Shifting a sequence of 64 zeroes into the USER1 DR is sufficient to cover the most conservative case for m and n.