ISE Mapping problem

[Yaseen Zaidi]

Hello there,

I've got a hard-wired asyncrhonous reset coming into GCK on a Spartan
XC2S200 device. The reset is used within three different processes in
VHDL code. However, beyond Synthesis and Translation, ISE errors
during Mapping. Apparently it is trying to control the packing of
flip-flops or latches within an I/O cell. Normally, the Mapper packs
devices within an I/O cell only if such packing is specified by the
design entry method. However, I don't do this intentially. I can't
move the reset to a general I/O as it is fixed in hardware. My
experience has not been good with GCK's as I/Os beside clock use. I
can't change the LOC constraint in the UCF to a different physical
location as this is the only reset available. How can I get rid of
this error w/o modifying the code? Tnx,

YZ

-- MAPPING ERROR

ERRORack:1107 - Unable to combine the following symbols into a
single IOB component: PAD symbol "Rx_Reset" (Pad Signal = Rx_Reset)
BUF symbol "Rx_Reset_IBUF" (Output Signal =
Rx_Reset_IBUF)

Each of the following constraints specifies an illegal physical site
for a component of type
IOB: Symbol "Rx_Reset" (LOC=P77)
Please correct the constraints accordingly.