Nios® V Embedded Processor Design Handbook

ID 726952
Date 5/13/2024

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6.2.1. JTAG Server

A JTAG Server communicates with the hardware and allows multiple programs to use JTAG resources concurrently. You can display the connected devices' JTAG scan chain to validate the Nios® V processor's presence in the Intel FPGA.

From the Nios® V Command Shell, the jtagconfig -d command identifies available JTAG devices and the number of CPUs in the subsystem connected to each JTAG device. The example below shows the system response to a jtagconfig -d command.

System Response to JTAG Server

$ jtagconfig -d
1) AGF FPGA Development Kit on Intel® FPGA Download Cable [USB-0]
   (JTAG Server Version 22.1.0 Build 174 03/30/2022 SC Pro Edition)
  C341A0DD   AGFB014R24A(.|R1|R2)/.. (IR=10)
    Design hash    74DFB795DF11A555CEDF
    + Node 00486E00  Source/Probe #0
    + Node 08986E00  Nios V #0
    + Node 0C006E00  JTAG UART #0
  031830DD   10M16S(A|C|L) (IR=10)

  Captured DR after reset = (30D068376063061BB020D10DD) [98]
  Captured IR after reset = (006AAD55) [32]
  Captured Bypass after reset = (0A) [5]
  Captured Bypass chain = (00) [5]
  JTAG clock speed auto-adjustment is enabled. To disable, set JtagClockAutoAdjust parameter to 0
  JTAG clock speed 24 MHz

The response in the example lists one FPGA connected to the running JTAG server through Intel FPGA Download Cable. The cable attached to the USB-0 port is connected to a JTAG node in a Platform Designer subsystem with a single Nios® V processor core.

The node numbers represent JTAG nodes inside the FPGA.
  • The appearance of node number 0x08986Exx confirms that the FPGA implementation has a Nios® V processor with a JTAG debug module. The CPU instances are identified by the least significant byte of the nodes after 0x08986E.
  • The appearance of node number 0x0C006Exx confirms that the FPGA implementation has a JTAG UART component. The JTAG UART instances are identified by the least significant byte of the nodes after 0x0C006E.

All instance IDs begin with 0. Only the CPUs that have debug enabled appear in the listing. Use this listing to confirm that you have debug enabled for the Nios® V processors you intended.