Generate a clock for only test in COCOTB not connected to the DUT

Question

I am new to cocotb and I want to test my DUT.

I have one clock that input to the dut which i generate correctly, however, I want a clock to use it only in the test not connected to the DUT, I want this clock to be long and with each rising edge a do a test but O am suffering since yesterday to do such a clock

I have the following code

import cocotb
from cocotb.runner import get_runner
from cocotb.triggers import Timer, FallingEdge, RisingEdge
from cocotb.clock import Clock

    async def generate_clock(sim_clk, period):
    """Generate clock test."""
    while True:
        sim_clk <= 0
        await Timer(period // 2, units="ms")
        sim_clk <= 1
        await Timer(period // 2, units="ms")

@cocotb.test()
async def top(dut):
sim_clk = Clock('sim_clk', period=22)
cocotb.start_soon(generate_clock(sim_clk, 22))
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## this line is alwys error I tried everything but it gives error
await RisingEdge(dut.sim_clk)

How can make such clock I can use its rising edge but not eonnected to the dut

Answer 1

The main problem was cocotb prefer working with dut.clk and in case we want to make a clk only for the tesbench this will raise an issue for cocotb, I overcome this issue by adding a clock to the dut which only for the test and it passed. I searched a lot and using a delay for clock in cocotb is not a practical use.

clock_tb = Clock(dut.clk_tb, 22, units="ms")

cocotb.start_soon(clock_tb.start(start_high=False)) # it is important to start with falling edge

await RisingEdge(dut.clk_tb)

I belive this is the best use of the clock in cocotb

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