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@kbeckmann
Last active May 16, 2021 21:32
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nmigen reset problem
Issue: Why is counter2 not reset when reset is toggled?
couter1 counter2
0 0
1 1
2 1
3 2
4 2
0 2
1 3
2 3
3 4
4 4
from nmigen import *
from nmigen.sim import *
def main():
print("Issue: Why is counter2 not reset when reset is toggled?")
m = Module()
m.domains += ClockDomain("sync")
m.domains += ClockDomain("second")
# Create a second clock domain that's half the frequency of sync
clk_second = ClockSignal("second")
m.d.sync += [
clk_second.eq(~clk_second)
]
counter1 = Signal(16)
m.d.sync += counter1.eq(counter1 + 1)
counter2 = Signal(16)
m.d.second += counter2.eq(counter2 + 1)
# Tie a reset signal to both clock domains
reset = Signal()
m.d.comb += ResetSignal(domain="sync").eq(reset)
m.d.comb += ResetSignal(domain="second").eq(reset)
sim = Simulator(m)
sim.add_clock(1e-6)
print("couter1 counter2")
def process():
print(f"{(yield counter1)}\t{(yield counter2)}")
yield Tick(); yield Delay(1e-8)
print(f"{(yield counter1)}\t{(yield counter2)}")
yield Tick(); yield Delay(1e-8)
print(f"{(yield counter1)}\t{(yield counter2)}")
yield Tick(); yield Delay(1e-8)
print(f"{(yield counter1)}\t{(yield counter2)}")
yield Tick(); yield Delay(1e-8)
print(f"{(yield counter1)}\t{(yield counter2)}")
yield reset.eq(1)
yield Tick(); yield Delay(1e-8)
yield Tick(); yield Delay(1e-8)
yield Tick(); yield Delay(1e-8)
yield Tick(); yield Delay(1e-8)
yield reset.eq(0)
print(f"{(yield counter1)}\t{(yield counter2)}")
yield Tick(); yield Delay(1e-8)
print(f"{(yield counter1)}\t{(yield counter2)}")
yield Tick(); yield Delay(1e-8)
print(f"{(yield counter1)}\t{(yield counter2)}")
yield Tick(); yield Delay(1e-8)
print(f"{(yield counter1)}\t{(yield counter2)}")
yield Tick(); yield Delay(1e-8)
print(f"{(yield counter1)}\t{(yield counter2)}")
yield Tick(); yield Delay(1e-8)
sim.add_process(process)
with sim.write_vcd("test.vcd"):
sim.run()
if __name__ == '__main__':
main()
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