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AR# 2707

5.1i iMPACT - Is a generic BSDL file available that will allow me to bypass non-Xilinx devices with iMPACT or JTAG Programmer?

Description

General Description:

I would like to bypass a non-Xilinx device in a JTAG scan chain to run JTAG operations on a Xilinx device. Is a generic BSDL file available that will allow me to bypass the non-Xilinx devices?

Solution

iMPACT 6.1i allows you to specify the IR length, and it automatically generates the BSDL file for the bypass device.

A generic BSDL file can also be downloaded by clicking on the BSDL link at:

http://support.xilinx.com/support/software.htm

This BSDL file can be substituted for any bad or missing BSDL file. However, the following information is required, and should be provided by the manufacturer:

1. The number of bits in the INSTRUCTION register.

2. The BYPASS instruction bit pattern (this MUST always be all "1s", but always ensure that this is the case).

3. The INSTRUCTION register capture pattern (this allows for elementary boundary-scan chain testing).

The following is an example of a generic BSDL file:

-- Copyright Xilinx Corporation 1997

-- Bogus BSDL File

-- Updated: April 4, 1997

--************************************************************************

-- Generic BSDL file

-- Copyright Xilinx Corporation 1997

-- Xilinx assumes no liability, either expressed or implied, in the use of this BSDL file.

--*************************************************************************

entity nothing_at_all is

--*************************************************************************

-- IMPORTANT - If you are using multiple copies of this file in a single

-- boundary-scan chain, you must make certain that the entity name

-- specified in each generic BSDL file (in this file "nothing_at_all") is

-- unique. Note that the entity name occurs nine (9) times in this file

-- (not including once in this comment).

--*************************************************************************

generic(PHYSICAL_PIN_MAP : string:= "X_PACKAGE");

port ( TCK : in bit; TDI : in bit; TDO : out bit; TMS : in bit );

use STD_1149_1_1990.all;

attribute PIN_MAP of nothing_at_all :

entity is PHYSICAL_PIN_MAP;

constant X_PACKAGE:PIN_MAP_STRING :=

"TCK : 1," &

"TDI : 2," &

"TDO : 3," &

"TMS : 4";

attribute Tap_Scan_In of TDI : signal is true;

attribute Tap_Scan_Mode of TMS : signal is true;

attribute Tap_Scan_Out of TDO : signal is true;

attribute Tap_Scan_Clock of TCK : signal is (1.0e6, BOTH);

-- The information in the three attributes below should be modified per the

--- device manufacturer's instructions

-- The first attribute specifies the number of bits in the instruction register:

attribute Instruction_Length of nothing_at_all: entity is 4;

-- The second attribute specifies the bit code for the BYPASS instruction:

attribute Instruction_Opcode of nothing_at_all: entity is "BYPASS ( 1111)";

-- The third attribute specifies the bit pattern captured by the instruction

-- register. If you do not know the capture pattern, you may specify it as

-- all "X"s; however, you will lose the vitally important capability of

-- verifying the boundary-scan chain on-the-fly:

attribute Instruction_Capture of nothing_at_all : entity is "0001";

-- End of section that should be modified as per the device manufacturer's instructions

attribute Boundary_Cells of nothing_at_all: entity is " BC_1";

attribute Boundary_Length of nothing_at_all: entity is 1;

-- NOTE: The following statement must be entirely on one line:

attribute Boundary_Register of nothing_at_all: entity is " 0 (BC_1, *, control, 0)";

end nothing_at_all;

AR# 2707
Date Created 08/21/2007
Last Updated 12/15/2012
Status Active
Type General Article