Python package for making simple System Simulations using an event driven simulation framework.
The following code shows a minimal example of a testbench with a simple clock signal and a counter. The simulation is executed for 100 ns and generates a VCD file with all registered signals.
import sysim
class Counter(sysim.Module):
"""A simple clocked integer counter."""
def __init__(self, **kwargs):
super().__init__(**kwargs)
# Create clock input
self.clk_i = sysim.input(sysim.Bit)
# Create counter output
self.cnt_o = sysim.output(sysim.Int)
@sysim.process
def run(self):
"""Main clocked process executed when simulation starts."""
# Reset clock output
self.cnt_o.assign(0)
# Counter will run until simulation finishes
while True:
# Wait for a rising edge on the clock
yield self.clk_i.rising_edge()
# Update counter value
self.cnt_o <<= self.cnt_o.value + 1
class TB(sysim.Module):
"""A simple testbench for the counter module."""
def __init__(self):
super().__init__()
# Create testbench signal for clock with default value 0
self.clk = sysim.signal(sysim.Bit, 0)
# Create testbench signal for counter value
self.cnt = sysim.signal(sysim.Int)
# Instantiate counter and bind ports to testbench signals
self.i_cnt = Counter(clk_i=self.clk, cnt_o=self.cnt)
@sysim.process
def clock(self):
"""Clock process running forever."""
while True:
# Generate square wave on clock with 20 ns period (all times
# are in units of seconds)
self.clk <<= 1
yield sysim.wait(10e-9)
self.clk <<= 0
yield sysim.wait(10e-9)
# Create an instance of the testbench
tb = TB()
# Create a VCD type logger
logger = sysim.VcdLogger("test_cnt.vcd")
# Initialize simulation with a timescale of 1 ns and the specified logger
sysim.initialize(tb, 1e-9, logger)
# Run simulation for 100 ns
sysim.run(100e-9)
logger.flush()
assert tb.cnt.value == 5pySySim requires Python >= 3.7, pyVCD and SimPy. The requirements should be installed automatically as they are available on PyPI.
Install locally using pip:
$ pip3 install -e pysysimIn the docsfolder simply run
$ make htmlto build the documentation, which can then be found in the build folder.