Answers Database

XEPLD, XC7318, XC7336: nd100:[Error] (nd104, hi317) Could not map '<instance>' into a fast function block. (Fast Clocks)


Record #1632

Product Family:  Software

Product Line:  EPLD Core

Problem Title:
XEPLD, XC7318, XC7336:  nd100:[Error] (nd104, hi317) Could not map
'<instance>' into a fast function block. (Fast Clocks)



Problem Description:
Keywords:  7318, 7336, fclk, fast function block, fast clock,
	   hi317, nd100, nd104

Urgency:  Standard

General Description:

Upon implementing a XC7318 or XC7336 design the following
errors may be encountered during the optimize stage of
implementation:

nd100:[Error]Could not map '<instance>' into a fast function
      block macrocell.
nd104:[Error]Device does not have enough fast clocks to convert
      macrocell pterm clock into a fast clock as required for
      fast function blocks.
hi317:[Error]Invalid fast function mapping requirement found.
      Possibly there is too much logic declared as fast in your
      design.

This error is typically caused by a design which targets the
XC7318 or the XC7336 and which uses more than two device
clocks.  Since the XC7318 and XC7336 have *only* Fast Function
Blocks, the device may only have 2 clocks.  This is because the
clocks in Fast Function Blocks can come from one of two places,
the FCLK0 pin or the FCLK1 pin.  Even if the design generates a
clock signal internally, the clock signal will still need to
use one of these 2 FCLK pins to get back into the device on a
clock line.

There are no product term clocks in Fast Function Blocks

Therefore, if the design has an internally generated clock(s),
a FCLK pin must be left free for each of those internally
generated clock(s).


Solution 1:

Target a 7300 device that contains High Density Function
Blocks such as the 7354 or larger device.

You may also try targeting an equivelent 9500 device.



Solution 2:

Limit the number of clocks in the design to 2.



Solution 3:

If the design contains an internally generated clock(s), be
sure that there is a corresponding FCLK pin available for the
clock to use to get onto the clock line.



End of Record #1632