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# lib_sw_pll: Software PLL library

vendor:

  XMOS

version:

  2.4.1

scope:

  General Use

description:

  PLL functionality using a combination of software and on-device PLL

category:

  Audio

keywords:

  PLL, clocking

devices:

  xcore.ai

## Summary

This library provides software that, together with the xcore.ai application PLL, provides a PLL that will generate a clock that is phase-locked to an input clock.

It supports both Look Up Table (LUT) and Sigma Delta Modulated (SDM) Digitally Controlled Oscillators (DCO), a Phase Frequency Detector (PFD) and configurable Proportional Integral (PI) controllers which together form a hybrid Software/Hardware Phase Locked Loop (PLL).

Examples are provided showing a master clock locking to a low frequency input reference clock and also to an I²S slave interface.

In addition, an API providing a range of fixed clocks supporting common master clock frequencies between 11.2896 MHz and 49.152 MHz is available in cases where phase locking is not required.

## Features

- High quality clock recovery using on-board PLL

- Flexible clock reference (external pin or internal source)

- Low resource usage

- Optional Sigma-Delta Modulator

- Fixed output clock option for typical audio master clocks

- Hardware locks: fast and power efficient but there are a limited number per tile

- Software locks: slower but an unlimited number can be used

## Known issues

- None

## Development repo

- lib_sw_pll

## Required tools

- XMOS XTC Tools: 15.3.1

## Required libraries (dependencies)

- None

## Related application notes

- None

## Support

This package is supported by XMOS Ltd. Issues can be raised against the software at www.xmos.com/support