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Introduction
System-Level Debugging Infrastructure
Virtual JTAG Interface Description
Run-Time Communication
Instantiating the Virtual JTAG Intel® FPGA IP Core
Simulation Support
Compiling the Design
SLD_NODE Discovery and Enumeration
Capturing the Virtual IR Instruction Register
AHDL Function Prototype
VHDL Component Declaration
VHDL LIBRARY-USE Declaration
Design Example: TAP Controller State Machine
Design Example: Modifying the DCFIFO Contents at Runtime
Design Example: Offloading Hardwired Revision Information
Document Revision History for the Virtual JTAG Intel® FPGA IP Core User Guide
Visible to Intel only — GUID: bhc1411109429152
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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.