amaranth/examples/basic/por.py

from amaranth import *
from amaranth.cli import main


m = Module()
cd_por  = ClockDomain(reset_less=True)
cd_sync = ClockDomain()
m.domains += cd_por, cd_sync

delay = Signal(range(256), reset=255)
with m.If(delay != 0):
    m.d.por += delay.eq(delay - 1)
m.d.comb += [
    ClockSignal().eq(cd_por.clk),
    ResetSignal().eq(delay != 0),
]

if __name__ == "__main__":
    main(m, ports=[cd_por.clk])