conn

type Conn interface {
	String() string
	// Tx does a single transaction.
	//
	// For full duplex protocols (generally SPI, UART), the two buffers must have
	// the same length as both reading and writing happen simultaneously.
	//
	// For half duplex protocols (I²C), there is no restriction as reading
	// happens after writing, and r can be nil.
	//
	// Query Limits.MaxTxSize() to know if there is a limit on the buffer size
	// per Tx() call.
	Tx(w, r []byte) error
	// Duplex returns the current duplex setting for this point-to-point
	// connection.
	//
	// It is expected to be either Half or Full unless the connection itself is
	// in an unknown state.
	Duplex() Duplex
}

type Duplex int

type Limits interface {
	// MaxTxSize returns the maximum allowed data size to be sent as a single
	// I/O.
	//
	// Returns 0 if undefined.
	MaxTxSize() int
}

type Resource interface {
	// String returns a human readable identifier representing this resource in a
	// descriptive way for the user. It is the same signature as fmt.Stringer.
	String() string
	// Halt stops the resource.
	//
	// Unlike a Conn, a Resource may not be closable, On the other hand, a
	// resource can be halted. What halting entails depends on the resource
	// device but it should stop motion, sensing loop, light emission or PWM
	// output and go back into an inert state.
	Halt() error
}