amaranth/examples/basic/gpio.py

from nmigen import *
from nmigen.cli import main


class GPIO(Elaboratable):
    def __init__(self, pins, bus):
        self.pins = pins
        self.bus  = bus

    def elaborate(self, platform):
        m = Module()
        m.d.comb += self.bus.r_data.eq(self.pins[self.bus.addr])
        with m.If(self.bus.we):
            m.d.sync += self.pins[self.bus.addr].eq(self.bus.w_data)
        return m


if __name__ == "__main__":
    bus = Record([
        ("addr",   3),
        ("r_data", 1),
        ("w_data", 1),
        ("we",     1),
    ])
    pins = Signal(8)
    gpio = GPIO(Array(pins), bus)
    main(gpio, ports=[pins, bus.addr, bus.r_data, bus.w_data, bus.we])