Answers Database

FPGA Express 2.0/Synopsys: RISING_EDGE vhdl syntax not supported. (VHDL-2204)


Record #3679

Product Family:  Software

Product Line:  Synopsys

Problem Title:
FPGA Express 2.0/Synopsys:  RISING_EDGE vhdl syntax not supported. 
(VHDL-2204)



Problem Description:
Keywords:  RISING, EDGE, vhdl, syntax, 2204, Express, Synopsys

Urgency:  Standard

General Description:
When the syntax "RISING_EDGE" is used within a VHDL design analyzed by
FPGA Express 1.x or 2.0.x, the following error will occur:


Error:	Could not find object subprogram RISING_EDGE.  This error can occur if
a package (World) that exists in memory also exists in another library referred
to in a Library statement.  This error can also occur if the package uses
synthesis_off/synthesis_on directives around the object.  (VHDL-2204)


Solution 1:

RISING_EDGE is not supported by FPGA Express 1.x or 2.0.x.

RISING_EDGE(CLK)

should be replaced by

(CLK'event and CLK='1')


RISING_EDGE is a feature that will be supported in a future release of
FPGA Express.



End of Record #3679