It's easier to use GPIO extensions over I2C (p.e. MCP23008). Some of them even have interrupt logic so you can build almost anything you'd do with the internal pins (OK, not truly as fast, but for a pinball more than fast enough).
It's easier to use GPIO extensions over I2C (p.e. MCP23008). Some of them even have interrupt logic so you can build almost anything you'd do with the internal pins (OK, not truly as fast, but for a pinball more than fast enough).