Jeffry Keip
Senior Staff Product Marketing Manager
Published: January 30, 2021

I am delighted you are interested in learning more about the pcm4l software Renesas has developed, PTP (Precision Time Protocol) Clock Manager for Linux. As we launch the software for broad use, we have a fair bit of material available on the website. This blog will help you navigate through the material available to achieve your goal of establishing a functional IEEE 1588 synchronized system. I have also collected links to additional material, so you don’t need to search for those yourself.

PCM4L Quick Start Guide: This step-by-step guide is the first document you should access. Following the directions in this document is strongly recommended.

Linux PTP Using PHC Adjust Phase Reference Manual: This document outlines the system requirements. It is a useful tool to help get the ptp4l up and running properly, an important step to complete before you begin working with the pcm4l software.

Items that are presented in bold, italic type are considered very sensitive material. Customers are not permitted to distribute these materials. There is an extra layer of security for those wishing to obtain these materials. Approval to download will rarely take more than one working day. If you have a contact at Renesas with whom you have discussed your need for the material, I recommend you call them to speed up the process.

  • pcm4l Software: This is the link to the latest software. You will need to agree to the terms of our license before you will be allowed to download the software. The next two documents are important companions to assist you in getting the pcm4l software running correctly.
  • PTP Clock Manager for Linux Datasheet: This is the corollary to a hardware datasheet for the software. This is where to look if you want more detail on the Principles of Operation, Software Architecture, Start-Up configuration, and to see MTIE analysis plots that demonstrate the performance of the software.

PTP Clock Manager for Linux Reference Manual: This details the system requirements (Linux needs, Network interface) and guides you through some configurations, a sample session, and troubleshooting tips.

pcm4l: Basic Debugging Steps for Renesas PTP Clock Manager Software: This document explains how to debug the integration of pcm4l (PTP Clock Manager Software) version 4.0.1. You should confirm the operation of ptp4l before running pcm4l. For ptp4l to work correctly, the Linux drivers for both the time stamper and the ClockMatrix™ device need to be working correctly. The pcm4l program uses the same interfaces as ptp4l to add more advanced filtering of the time stamps for networks with high PDV and other features needed to support the ITU PTP profiles.

The Linux PTP Hardware Clock Subsystem for 5G O-RAN White Box Hardware: This whitepaper reviews the Linux PTP Hardware Clock (PHC) subsystem infrastructure and the uses of the PHC as an interface to both software-based and hardware-based servos that provide the Telecom synchronization interfaces required to meet ITU-T network limits for 5G Radio Access Network (RAN).

Linux Kernel PTP Hardware Clock Infrastructure: This white paper discusses the Linux kernel PTP hardware clock (PHC) infrastructure and how it is used with hardware timestamping to implement accurate PTP slave clocks. The PHC infrastructure offers standardized APIs for user space applications and Linux kernel device drivers that simplify system integration. This whitepaper also outlines the APIs provided by the PHC infrastructure and how they interact with timing hardware devices.

Limiting IEEE 1588 Slave Clock Wander Caused by Packet Delay Variation: This white paper compares two IEEE 1588 slave clock implementations for effectiveness in limiting wander caused by packet delay variation (PDV). The implementations are:

  • An IEEE 1588 slave clock that includes a PDV filter in the servo loop
  • An IEEE 1588 slave clock that includes a low-pass filter in the servo loop

Demo Videos: Explain the devices in use, connections and overall system level test setup as well as the steps to follow to run the program. Results obtained are discussed demonstrating compliance with the standards.

The zipped folder labeled “pcm4l Quick Start Files” contains the files listed below which are used in conjunction with the “pcm4l Software Quick Start Guide”.

Beyond the material available on this website, there are a few other things that reside elsewhere that you will need. Links below are provided for your convenience:

  1. Linux PTP stack v3.0 or later. Here is a link (linuxptp download | where you can download it from the Network Time Foundation at SourceForge.
  2. Look in the “Linux PTP Using PHC Adjust Phase Reference Manual” for detailed assistance in obtaining the current ClockMatrix kernel.
  3. You will need the kernel driver for the PHY/TSU you are working with. The vendor of that device is your best source for how and where to obtain that.

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