IMX8 PLUS PTP support

[Duraisamy_Pandurangan]

I reviewed the detailed information on the i.MX 8M Plus but still have some questions about PTP implementation and hardware timestamping.

There are two Ethernet controllers in this processor (called ENET and ENET_QOS). I am not quite sure whether the ENET_QOS controller supports timestamping from the 1588 counter as well. Do you have any comments on this?

For the ENET controller to support 1588 timestamping, the counter has only 32 bits, hence it can only cover the time within 1 second. Can software take care of the TOD beyond 1 second? If so, please explain how it works.

Duraisamy_Pandurangan_5-1710563137448.png

The 125 MHz clock coming from the PLL can be fed into those pins of the processor (133 MHz max). It will drive the 1588 counter. Can we use this pin for 125 MHz?

Duraisamy_Pandurangan_7-1710563301011.png

Can you please help to review my thoughts above?

[JosephAtNXP]

Hi,

Thank you for your interest in NXP Semiconductor products,

1. ENET supports 1588 timestamping and ENET_QOS support all 1588 timers to comply with TSN.

2. If you are planning to feed a 125 MHz for RGMII ang 1588 reference, you can use CLK_EXT as said but keep in mind the mappings.

josephlinares_0-1710736544276.png

If you are planing to use an extra reference (in addition to TXC) to the PHY, you can use the CLK_EXT1 ball,

josephlinares_1-1710736627526.png

Regards

[Duraisamy_Pandurangan]

Hi Josephilnares,

Thank you for your reply, But i have a concern about the counter has only 32 bits, hence it can only cover the time within 1 second. Can software take care of the TOD beyond 1 second? If so, please explain how it works.Because our requirement TOD error in nano second.

[JosephAtNXP]

Hi,

Yes, TOD is done in SW, counter is used to sync the value, as you can further read on this article that I found.

In this case, as you said, you'd need to use 1 pps to keep the timer off overflows.

Thank you,