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lib_sw_pll: Software PLL library

vendor:XMOS
version:2.3.1
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

Required tools

  • XMOS XTC Tools: 15.3.0

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