Answers Database
2.1i: How to initialize the contents of a RAM primitive via a constraint file
Record #4136
Product Family: Software
Product Line: FPGA Implementation
Product Part: ngdbuild
Problem Title:
2.1i: How to initialize the contents of a RAM primitive via a constraint file
Problem Description:
urgency: standard
general description:
It is possible to specify the initial contents of a XC4000/Virtex ram via
a constraint file. To specify the contents of a XC4000/Virtex ram, the user
must know the instance name(s) of the ram. Also, the type of constraint file
to use is a NCF file. A UCF file cannot be used to specify the contents of
a XC4000/Virtex ram.
Solution 1:
Use the following line in a NCF file(Note, that the NCF
file must have the same root name as the input netlist. e.g.
If the input netlist name was design.edf, then the NCF file
must be named design.ncf):
INST instname INIT = value;
Where instname is the instance name of the RAM, which must be
a RAM primitive, enclosed in quotes. 'value' is a hex number.
e.g. If the instance name of a RAM32X1S is U1, the contents of
U1 could be set in the NCF file by placing the following line
in a NCF file:
INST "U1" INIT=AAAA0000;
End of Record #4136 - Last Modified: 11/04/99 09:17 |
