HW timestamping (PTP/IEEE1588) on raspberry pi 4?

Hello,

can anyone tell me if the new RaspberryPi4 is capable of hardware timestamping according to IEEE1588/PTP?

Regards

Reply to
heiko.bruckmeyer
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On Mon, 29 Jul 2019 00:32:15 -0700 (PDT), snipped-for-privacy@gmail.com declaimed the following:

I highly doubt it... Given the requirements for

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(namely, NIC having 1588 hardware assist -- while the R-Pi4 provides a faster network interface, I doubt it includes special hardware at this price point -- the 82580 chip is $17 alone when ordering 200+ units).

Software-based ptpd appears as an option even in Stretch-based Raspbian...

md_admin@microdiversity:~$ apt-cache search ptpd bcrelay - Broadcast relay daemon pptpd - PoPToP Point to Point Tunneling Server ptpd - Precision Time Protocol daemon md_admin@microdiversity:~$

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	Wulfraed                 Dennis Lee Bieber         AF6VN 
	wlfraed@ix.netcom.com    http://wlfraed.microdiversity.freeddns.org/
Reply to
Dennis Lee Bieber

It's unclear which ethernet MAC the Pi4 is actually using - we know it uses the Broadcom GENET driver, which is used by some BCM7xxx set top box chips, but as usual with Broadcom we don't get any documentation. The Linux driver is pretty minimal and doesn't do much beyond transferring packets.

Until such time as more data comes out, I don't think we'll be any the wiser.

Theo

Reply to
Theo

I'm sure it can be a slave, it's just a Linux computer, but the Pi (any version) doesn't even have a hardware clock, so probably useless as a ptp master.

Reply to
A. Dumas

There is a battery backed RTC module for the Pi, and a number of people have interfaced to GPS based time signals. So there is no reason why a Pi can't be used for this.

---druck

Reply to
druck

"With additional hardware and sofware, an Apple II can put a man on the moon"

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Reply to
The Natural Philosopher

I wonder how much extra it would add to the purchase price of a Pi to include an RTC powered by a capacitor to keep things going until the Pi has rebooted. If you have a permanent internet connection, it's no problem because as soon as the Pi boots it resyncs with a time source on the internet, but it can be a problem if a Pi is used with an intermittent internet connection.

OK, so we had a very unusual case: no ADSL/VDSL internet connection in our new house for a few weeks, so I was relying on tethering my PC and Pi to the mobile phone internet. That was fine until my Pi rebooted when there was no mobile in range, and its time reset itself to an hour or so earlier. That screwed up the data for my weather station logging that my Pi does: I had to go in and hand-modify the time stamps on some readings until I realised the problem and synced the Pi to NTP.

Given the very portable nature of a Pi, and therefore the chance that it may be used on projects that don't have an internet connection, it needs to be resilient to reboots when it's not able to see an NTP source or when the date/time can't be modified manually.

But maybe an external RTC for those special cases is more cost-effective than adding it to the Pi where it is not needed for situations where there is access to NTP.

Reply to
NY

Hanging a GPS receiver on it could be a neat solution.

Are there any suitably packaged units and interfacing software available?

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Martin    | martin at 
Gregorie  | gregorie dot org
Reply to
Martin Gregorie

On Wed, 31 Jul 2019 17:14:59 +0000 (UTC), Martin Gregorie declaimed the following:

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	Wulfraed                 Dennis Lee Bieber         AF6VN 
	wlfraed@ix.netcom.com    http://wlfraed.microdiversity.freeddns.org/
Reply to
Dennis Lee Bieber

Thanks for those, especially the first link - that's a goldmine.

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Martin    | martin at 
Gregorie  | gregorie dot org
Reply to
Martin Gregorie

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