Re: [ts-7000] Not enough stable clock after synchronizing with ntp server.

[Ian Thompson <>]

Dave

The principal factors are the OSes and their IP stacks. You can't depend on when NTP events are going to get handled if you are running a general purpose OS. You might improve the accuracy if you code your NTP servers and clients on an RTOS with a more deterministic IP stack.
There are efforts to put PTP/IEEE-1588 handling into the Linux kernel. I'm not sure if this is to support specific PTP enabled hardware or to move the handling of PTP events to early in the stack.

Ian T.

On 08/25/2010 09:02 AM, Dave Cramer wrote:

 

On Wed, Aug 25, 2010 at 9:45 AM, Ian Thompson <m("pgs.com","ian.thompson");">> wrote:

 

It's not considered possible to synchronize to better than ±20 mS with
NTP,

What are the limiting factors here ? I will have all of my boards on the same local network.

 

hence the introduction of PTP [Precision Time Protocol or IEEE-1588] .
To get microsecond accuracy with PTP one needs an Ethernet MAC with
built in hardware support and a PTP master. I don't believe Technologic
have any boards that include this as yet. I hope that they are
considering adding it!

What exactly is required ?

Dave

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