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AR# 8487

6.1i XST - What implementation (back-end) constraints does XST recognize?

Description

Keywords: constraints, implementation, back end, XST, 5.1i

Urgency: Standard

General Description:
What implementation constraints does XST recognize and pass on to the NGC file?

Solution

The User Guide does not contain an exhaustive list of back-end constraints that are supported by XST; please see the list below.

"NOVALUE": XST must write a constraint into the NGC file without any value.
"VALUE": XST must write a constraint into the NGC with a value specified in the HDL or constraint file.

For a complete description of the constraints listed below, please refer to the Constraints Guide, located at:
http://www.xilinx.com/support/software_manuals.htm

Virtex/Virtex-II constraints:

FAST...........................................NOVALUE
KEEP...........................................NOVALUE
KEEPER......................................NOVALUE
LOCK_PINS.................................NOVALUE
NODELAY....................................NOVALUE
PULLUP.......................................NOVALUE
PULLDOWN................................NOVALUE
S...................................................NOVALUE
TIG...............................................NOVALUE
USELOWSKEWLINES................NOVALUE
ALLCLOCKNETS.........................VALUE
BLKNM.........................................VALUE
CLKDV_DIVIDE...........................VALUE
CLKFX_DIVIDE............................VALUE
CLKFX_MULTIPLY......................VALUE
CLKIN_DIVIDE_BY_2..................VALUE
CLKIN_PERIOD...........................VALUE
CLKOUT_PHASE_SHIFT............VALUE
CLK_FEEDBACK.........................VALUE
DESKEW_ADJUST.....................VALUE
DFS_FREQUENCY_MODE.........VALUE
DLL_FREQUENCY_MODE.........VALUE
DRIVE..........................................VALUE
DSS_MODE.................................VALUE
DUTY_CYCLE..............................VALUE
DUTY_CYCLE_CORRECTION....VALUE
INIT..............................................VALUE
INIT_A..........................................VALUE
INIT_B..........................................VALUE
INIT_xx.........................................VALUE
INITP_xx......................................VALUE
IOB...............................................VALUE
IOSTANDARD..............................VALUE
HU_SET.......................................VALUE
INPAD_TO_OUTPAD..................VALUE
LOC..............................................VALUE
MAP.............................................VALUE
OFFSET_IN_BEFORE.................VALUE
OFFSET_OUT_AFTER................VALUE
PERIOD.......................................VALUE
PHASE_SHIFT.............................VALUE
RLOC...........................................VALUE
SLEW...........................................VALUE
SRVAL.........................................VALUE
SRVAL_A.....................................VALUE
SRVAL_B.....................................VALUE
STARTUP_WAIT.........................VALUE
TNM.............................................VALUE
U_SET.........................................VALUE
WRITE_MODE............................VALUE
WRITE_MODE_A........................VALUE
WRITE_MODE_B........................VALUE
XBLKNM.......................................VALUE

CPLD constraints:

DUAL_EDGE..............................NOVALUE
FAST...........................................NOVALUE
INREG.........................................NOVALUE
KEEP...........................................NOVALUE
KEEPER......................................NOVALUE
NOREDUCE................................NOVALUE
OPEN_DRAIN.............................NOVALUE
PULLUP......................................NOVALUE
SLOW.........................................NOVALUE
SOURCE_NODE........................NOVALUE
SIGNAL_PRESERVE.................NOVALUE
SCHMITT_TRIGGER.................NOVALUE
BUFG.........................................VALUE
INIT............................................VALUE
IOSTANDARD...........................VALUE
LOC............................................VALUE
MAXPT.......................................VALUE
PIN_ASSIGN..............................VALUE
PWR_MODE..............................VALUE
REG...........................................VALUE
TNM...........................................VALUE
AR# 8487
Date Created 01/24/2000
Last Updated 10/20/2005
Status Archive
Type General Article