Linux/AM3358: IEEE1588v2 clock precision

The Ethernet experts have been notified. They will respond here.

We have another question.

As IEEE1588v2 In AM3358, how much precision time can synchronize in Grandmaster-clock with  starter-kit?

Hello,

Apologies for the delay in responding to your first post. I'm waiting to hear back from our SW guru, but responses will be delayed for the holiday.

From a HW perspective, there is no dedicated PPS signal available. There may be a supported SW solution that involves CPTS + TIMER + GPIO, but I'd need SW to comment.

As to your second question, this value has not been characterized by TI.

Hello,

I expect the reply of SW group as soon as possible.

Best Regards,

Hi,

I will have to look further but at the moment TI does not have benchmark numbers to publish concerning the precision relative to a grand master clock.

There is a PTP daemon provided in the TI Processors Linux SDK. Here is a link to how to use it if you have not seen already.

processors.wiki.ti.com/.../Linux_Core_CPSW_User's_Guide

Do you have a starter kit EVM and if so which version of the TI Processor Linux SDK are you working with?

Best Regards,
Schuyler

Thank you for your reply.
We have a starter kit EVM version 03.00.00.04 of the TI Processor Linux SDK.

Can we use command "# testptp -c" on latest version with SDK?
Can we output pulse per second by command "# testptp -c"?

Hi,

I will have to check on if testptp is useable in the way you are asking. I have not used this application yet.

Best Regards,
Schuyler Patton

Hello,

Thanks, we are waiting for your solution as soon as possible.

By the way,
Do you have equipment of "Paragon-X"?
www.calnexsol.com/.../paragon-x

I guess you can measure precision time without PPS if you have that equipment.

Best Regards,

Hi,

As I mentioned previously TI does not have benchmarks numbers yet for the AM335x. Currently we do not have the test equipment necessary to test the jitter you are requesting. I apologize for not responding in regards to the ptptest question, I will respond to your question on this tomorrow.

Best Regards,
Schuyler

Hi,

Currently there is not a way to directly generate a PPS signal on the AM335x. This wiki page describes a possible method that was tried on Beagle Bone Black to output a HW Time Stamp push. This sets up a PWM timer. Please note that the example sets the frequency at 1 S and is not adjusted as the system clock changes for with ptp4l traffic. A task will need to be written to adjust the pwm timer to reflect the system clock jitter.

processors.wiki.ti.com/.../Linux_Core_CPSW_User's_Guide

Could you please post the results of uname -a of the kernel that you are using? The example is based a fairly recent kernel.

Best Regards,
Schuyler

Hello,

Thank you for your reply.

The kernel version that we are using is "4.4.12".

Linux version 4.4.12-g3639bea54a (fttec@FTEN46503DT) (gcc version 5.3.1 20160113 (Linaro GCC 5.3-2016.02) ) #1 PREEMPT Thu Nov 3 17:41:41 JST 2016

Please tell me about the BeagleBone Black.

This device can not output PPS signal, but can output Timestamp on display. Is my understanding correct?

And We think that "Starter Kit" can do this too.

How do you think?

Hi,
The example showed using the testptp program returning a timestamp. I am not I understand what you are saying on display, do you mean the console? Or writing an application to display the timestamp on the LCD display?

It is possible to change to a later SDK? The version that you are using is about 2 years out of date. Significant work was done in the past year concerning ptp support.

Best Regards,
Schuyler

Dear, Schuyler

Thank you for your reply.
We want to know the your answer about some items.

1.) You said we can use the testptp program returning a timestamp with Beagle Bone Black.
Can we use the testptp program with Starter Kit (TMDSSK3358)?

2.) Can we check hardware pulse of timestamp?
Or only on program?

Best Regards,