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PTP

Precise Time Protocol (on Raspberry Pi 5)

Assuming 2 Raspberry Pis are connected with an Ethernet cable, and both have an IP on eth0.

Install

Install on both master and slave:

sudo apt install linuxptp

Verify that there is support on 'eth0'. Should have hardware capabilities:

$ ethtool -T eth0
Time stamping parameters for eth0:
Capabilities:
       hardware-transmit
       software-transmit
       hardware-receive
       software-receive
       software-system-clock
       hardware-raw-clock

Test time master

Start connection to eth0 hardware (as a process in the background)

sudo phc2sys -s CLOCK_REALTIME -c eth0 -w &

Start clock master service on eth0

sudo ptp4l -i eth0 -m -2

It should be activated as a grand master soon.

Test time client

Run a PTP test slave (-s) with output to console (-m).

sudo ptp4l -i eth0 -m -2 -s 

After a few minutes, this should yield a time offset on the order of 100 ns.

Kill the phc2sys on the time server after the client test:

sudo pkill phc2sys

Install as a service on Master

Most is copied from https://austinsnerdythings.com/2025/02/18/nanosecond-accurate-ptp-server-grandmaster-and-client-tutorial-for-raspberry-pi/.

Create a service file for the connection to eth0:

sudo nano /etc/systemd/system/phc2sys-grandmaster.service

With:

[Unit]
Description=sync PHC with system clock (grandmaster)
After=network-online.target
Wants=network-online.target

[Service]
Type=simple
ExecStart=/usr/sbin/phc2sys -s CLOCK_REALTIME -c eth0 -w
Restart=always
RestartSec=3

[Install]
WantedBy=multi-user.target

Create a service file for the ptp server:

sudo nano /etc/systemd/system/ptp4l-grandmaster.service

With:

[Unit]
Description=Precision Time Protocol (PTP) service (Grandmaster)
After=network-online.target
Wants=network-online.target

[Service]
Type=simple
ExecStart=/usr/sbin/ptp4l -i eth0 -2
Restart=always
RestartSec=3

[Install]
WantedBy=multi-user.target

Enable and start these services

sudo systemctl daemon-reload
sudo systemctl enable phc2sys-grandmaster.service
sudo systemctl enable ptp4l-grandmaster.service
sudo systemctl start phc2sys-grandmaster.service
sudo systemctl start ptp4l-grandmaster.service

Install as a service on the client

Make a new service file

sudo nano /etc/systemd/system/ptp4l-client.service

With:

[Unit]
Description=Precision Time Protocol (PTP) service (Client)
After=network-online.target
Wants=network-online.target

[Service]
Type=simple
ExecStart=/usr/sbin/ptp4l -i eth0 -2 -m --summary_interval 3
Restart=always
RestartSec=3

[Install]
WantedBy=multi-user.target

Also, enable and start this service:

sudo systemctl daemon-reload
sudo systemctl enable ptp4l-client.service
sudo systemctl start ptp4l-client.service

Check the status of the client when all is in place

sudo systemctl status ptp4l-client