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Signal Spy
init_signal_driver
Related procedures
init_signal_spy, signal_force, signal_release
Limitations
•
For the VHDL init_signal_driver procedure, when driving a Verilog net, the only
delay_type allowed is inertial. If you set the delay type to mti_transport, the setting will
be ignored and the delay type will be mti_inertial.
•
For the Verilog $init_signal_driver task, when driving a Verilog net, the only delay_type
allowed is inertial. If you set the delay type to 1 (transport), the setting will be ignored,
and the delay type will be inertial.
•
For the SystemC init_signal_driver function, when driving a Verilog net, the only
delay_type allowed is inertial. If you set the delay type to 1 (transport), the setting will
be ignored, and the delay type will be inertial.
•
Any delays that are set to a value less than the simulator resolution will be rounded to
the nearest resolution unit; no special warning will be issued.
•
Verilog memories (arrays of registers) are not supported.
$init_signal_driver Example
This example creates a local clock (clk0) and connects it to two clocks within the design
hierarchy. The .../blk1/clk will match local clk0 and a message will be displayed. The .../blk2/clk
will match the local clk0 but be delayed by 100 ps. For the second call to work, the .../blk2/clk
must be a VHDL based signal, because if it were a Verilog net a 100 ps inertial delay would
consume the 40 ps clock period. Verilog nets are limited to only inertial delays and thus the
setting of 1 (transport delay) would be ignored.
`timescale 1 ps / 1 ps
module testbench;
reg clk0;
initial begin
clk0 = 1;
forever begin
#20 clk0 = ~clk0;
end
end
initial begin
$init_signal_driver("clk0", "/testbench/uut/blk1/clk", , , 1);
$init_signal_driver("clk0", "/testbench/uut/blk2/clk", 100, 1);
end
...
endmodule
ModelSim User’s Manual, v6.3g
May 2008
301