SysIO-rs

A native Rust extension for Python providing direct GPIO, SPI (MCP3008) and RS-485 serial access on Linux, with no external dependencies beyond pyo3 and libc. Currently used for super performance critical components of my py projects.

Features

GPIO via /dev/gpiomem + mmap

• setmode(mode: "BOARD" | "BCM")
• setup(pin: int, direction: "IN" | "OUT")
• output(pin: int, value: 0 | 1)
• input(pin: int) -> int

SPI

• MCP3008(bus: int, cs: int, channel: int, speed_khz: int)
  • .read_raw() -> int (0–1023)
  • .value -> float (0.0–1.0)
  • .bits() -> int (const. 10)
  • .read() -> (raw: int, normalized: float)

RS-485 Serial via termios + direction-pin toggling

• Serial(path: str, baud: int, timeout_s: float, de_pin: int, ...)
  • .write(data: bytes) -> int
  • .read(size: int) -> bytes
  • .in_waiting() -> int
  • .flush()
  • .reset_input_buffer()
  • .reset_output_buffer()
  • .close()

Utility

• sleep_s(s: float)
• sleep_ms(ms: float)
• sleep_us(us: float)
• time_time()

Modules

GPIO

• Manages memory-mapped I/O for Raspberry Pi
• Lazy init of /dev/gpiomem
• Thread-safe via OnceLock

SPI

• Raw SPI ioctl calls to /dev/spidevX.Y
• Custom _IOC helper to calculate request codes

Serial

• Opens serial port non-blocking, toggles DE-pin for RS-485
• Configures termios for raw mode and timeouts
• Methods mirror Python serial package