SPI-based driver for shift registers

This is an embedded Rust driver for shift registers (such as 74HC595).

Features

• Fast communication using SPI peripheral.
• Implements OutputPin trait.
  • Pins of shift registers can be accessed (and passed to other libraries) like microcontroller pins.
• Supports unlimited daisy chain.
  • Size is specified using const generics

Usage

// Initialize a 8-bit shift register
let shift_reg: SipoShiftReg<_, 8, 1> = SipoShiftReg::new(spi);
// Get an array of individual pins
let mut pins = shift_reg.split();

// Set state of a pin
pins[0].set_high().unwrap();
pins[1].set_low().unwrap();

spi is an SPI driver object which implements SpiDevice.