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AR# 14025

2.2 MicroBlaze - I am unable to connect to XMDSTUB via a JTAG UART after downloading a bitstream with iMPACT

Description

Keywords: JTAG, UART, debug, XMD, connect

Urgency: Hot

General Description:
After implementing a design with the XMDSTUB program and downloading it to a board, I am unable to connect XMD to the board. The following messages are reported in the terminal:

"$ xmd -t hw -c j
MicroBlaze XMD Engine
Using Hardware board debugging through XMD stub
AutoDetecting cable. Please wait.
Connecting to cable (USB Port).
Cable connection failed.
Connecting to cable (Parallel Port - LPT1).
Cable connection failed.
Connecting to cable (Parallel Port - LPT2).
Cable connection failed.
Connecting to cable (Parallel Port - LPT3).
Cable connection failed.
Connecting to cable (COM1 Port).
Cable connection failed.
Connecting to cable (COM2 Port).
Cable connection failed.
Connecting to cable (COM3 Port).
Cable connection failed.
Connecting to cable (COM4 Port).
Cable connection failed.
Cable autodetection failed.
Identifying chain contents ....INFO:iMPACT:501 - '1': Added Device UNKNOWN successfully.
--------------------------------------------------------------------------------
done.
--------------------------------------------------------------------------------
Position...PartName......Version............FileName
1.............UNKNOWN...UNKNOWN...NOT YET ASSIGNED
--------------------------------------------------------------------------------
Validating chain..."

A Windows error window then appears (or, on Solaris machines, a segmentation fault occurs).

The connection should have been established with the port that has the JTAG cable connected to it.

Solution

iMPACT holds the port if it is running in JTAG mode.

To avoid this problem, iMPACT must release the parallel port so that XMD can connect to it and communicate to the XMDSTUB program running on the Xilinx part. You can enable this by selecting Output -> Cable Disconnect.
AR# 14025
Date Created 03/01/2002
Last Updated 04/20/2007
Status Archive
Type General Article