Answers Database

CONCEPT2XNF 9404, 9502: Problems with GND and VCC symbols in XPADS_HDL library


Record #815

Product Family:  Software

Product Line:  Cadence

Problem Title:
CONCEPT2XNF 9404, 9502:	Problems with GND and VCC symbols in XPADS_HDL
library



Problem Description:
GND or VCC symbols from the XPADS_HDL library connected to symbol pins
do not work properly.  For a pin connected to a GND symbol, CONCEPT2XNF
5.1 writes out that pin with a net called "_SUPPLY_0" attached to it,
but does not add this net name to the list for the "PWR, 0" (GND) power
record.

For a pin connected to a VCC symbol, CONCEPT2XNF
5.1 writes out that pin with a net called "_SUPPLY_1" attached to it,
but does not add this net name to the list of nets declared as VCC
nets in the "PWR, 1" (VCC) power record.

For example, for a GND symbol attached to the I0 pin of a 3-input
AND gate, CONCEPT2XNF writes out a net called _SUPPLY_0 in the I0
pin record:

   SYM,14P_1,AND,LIBVER=2.0.0,SCHNM=and3b1
   PIN,I2,I,DIN2,
   PIN,I1,I,DIN3,
   PIN,I0,I,_SUPPLY_0,,INV	   <---------------
   PIN,O,O,ANDOUT,
   END


However, the "PWR, 0" record which defines all nets connected to GND
may look like:

   PWR,0,GND,VSS

when it should look like:

   PWR,0,GND,VSS, _SUPPLY_0

to connect the signal, _SUPPLY_0 to GND.


Solution 1:

If you must use the 9404 release, replace the GND and VCC
symbols as follows:

VCC:  Connect the pin to a net labeled VDD.
GND:  Connect the pin to a net labeled VSS.




Solution 2:

This problem is fixed in the 9502 release, which ships with Concept2xnf
5.2.  The VCC and GND symbols, (as well as all other components in the
XPADS_HDL library) should only be used within the context of the HDL
Direct design flow methodology.

If you are using HDL Direct design methodology, HDL Direct must be
ENABLED  when the schematic is written. This can be accomplished
either by:

1. typing "set hdl_direct on" in Concept before saving the schematic, or

2. adding the line, "set hdl_direct on" to your startup.concept file
before starting up Concept.



End of Record #815