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MODELSIM VLOG (MTI): WARNING: [TSCALE] - Module '...' does not have a `timescale directive in effect, but previous modules do
Record #889
Product Family: Software
Product Line: Model Technology
Product Part: Modelsim
Product Version: 5.2
Problem Title:
MODELSIM VLOG (MTI): WARNING: [TSCALE] - Module '...' does not have a `timescale directive
in effect, but previous modules do
Problem Description:
Urgency: Standard
General Description:
When simulating with ModelSim Vlog, what does the following warning mean:
WARNING: [TSCALE] - Module '...' does not have a `timescale directive in
effect, but previous modules do
Solution 1:
The `timescale can be declared in any file.
The UNISIMS has 100ps / 10ps.
The SIMPRIMS has 1ps / 1ps.
The glbl.v has 100ps / 10ps.
The smallest precision of all the timescale directives determines the
time unit of the simulation. For example,
`timescale 1 ns / 10 ps
module1 ();
...
endmodule
`timescale 100 ns / 1 ns
module2 ();
...
endmodule
`timescale 1 ps / 100 fs
module3 ();
...
endmodule
The first timescale indicates that the time units for module1 are in multiples
of 1 ns and it is precise to 10 ps. Thus, the smallest timestep for the
simulator is 10 ps.
The second timescale is 100 ns / 1 ns. Since 1 ns is greater than 10 ps,
the smallest timestep remains 10 ps.
The third timescale is 1 ps / 100 fs. Since 100 fs is smaller than 10 ps,
the smallest simulator timestep now becomes 100 fs.
The `timescale compiler directive is optional. Designs that do not
contain this require no modification and the default of 1 ns / 1 ns is used.
However, if the design includes a `timescale compiler directive for any
module definition, then all other modules definitions require this as well.
Otherwise, ModelSim Vlog flags this as a warning.
End of Record #889 - Last Modified: 12/14/99 14:44 |
