Answers Database

M1.3/M1.4 CPLD: Fitter warning xr5100 - Inserting an output buffer


Record #2334

Product Family:  Software

Product Line:  CPLD Implementation

Problem Title:
M1.3/M1.4 CPLD: Fitter warning xr5100 - Inserting an output buffer


Problem Description:
Keywords: hitop, 5100, bufg, ckbuf, buf, clk, sr, oe

Urgency: standard

General description:

Putting the BUFG=CLK/OE/SR property on internal BUF and CKBUF
symbols will cause the fitter to issue a warning xr5100. It
inserts an OBUF for BUFG=CLK on BUF or CKBUF symbol, and for
BUFG=OE on BUF symbol. The output PAD is generated with a name
consisting of the BUF/CKBUF's input net name appended with
"/OBUF" (not a user signal name). It also disconnects CKBUF
with BUFG=OE and trims all logic.


Solution 1:

1. Use BUF components instead of CKBUFs.

2. There is no known way of getting the fitter to not insert an
   OBUF.



End of Record #2334