In SystemVerilog, a clocking block is a construct that is used to model clock signals in a hardware system. Clocking blocks provide a way to model the behavior of clock signals, including their timing and synchronization, and to specify the clock domains in a design.
A clocking block is defined using the “clocking” keyword, followed by a clocking block name and an optional set of parameters. The clocking block contains a set of input and output signals that are associated with the clock domain, as well as a set of timing controls that specify the behavior of the clock.
Here is an example of a clocking block:
clocking cb @(posedge clk);
input valid;
output ready;
input [7:0] data;
timing from input valid to output ready = 10 ns;
endclocking
In this example, the clocking block is named “cb” and is associated with the positive edge of the signal “clk”. The clocking block includes three signals: “valid”, “ready”, and “data”. The “valid” signal is an input to the clocking block, the “ready” signal is an output, and the “data” signal is an input.
The clocking block also includes a timing control, which specifies that the delay from the rising edge of the “valid” signal to the rising edge of the “ready” signal should be 10 nanoseconds.
Clocking blocks are particularly useful for verifying the behavior of a design, as they provide a way to model the timing and synchronization of clock signals. They can also be used to specify clock domains in a design, which is important for ensuring that signals are properly synchronized between clock domains.
Overall, clocking blocks are an important construct in SystemVerilog for modeling clock signals and ensuring that a design behaves correctly with respect to timing and synchronization.