Choosing ethernet PHY TSN compliant for iMX93

[Bob_NXP_user]

Hello,

I have to design a custom board using iMX93 for a Time Sensitive Network application. I found the following information about TSN compliance into iMX93 datasheet: 

So I found an Ethernet Phy with the feature "TSN compliant" without any further details about it. I did a web research and someone said that 802.1 Qbv, 802.1 Qbu and Time based scheduling are implemented by MAC controller, while PHY has to care about the latency and nothing more than that. Is it true? Is there anything else I must check in order to choose a PHY for TSN application?

Thanks in advance

[JosephAtNXP]

Hi,

Thank you for your interest in NXP Semiconductor products,

As found in the internet, the features for IEEE 1588 need the frame preemption for time critical and shorting long frames, it's implemented by the MAC and when received, they're interpreted by the MAC.

Also the PHY side is ok, the PHY just improves latency when the accuracy really needs it, but for most cases, a regular PHY should do the trick, as IEEE 1588 can be explored in i.MX 93 EVK which features a regular PHY.

Conclusion, your application may or may not need a low latency PHY, but in both cases can use IEEE 1588 features.

https://iebmedia.com/technology/tsn/tsn-technology-basics-of-ethernet-frame-preemption-part-2/

Regards

[clay_miller · Accepted solution]

That is mostly true with the only exception being older PHYs that are not 802.3br complaint and would complain about the use of SMD for frame preemption over SFD. As far as latency, you are correct that it is the PHYs main concern, its just not strictly defined in any TSN spec, yet it is good for a TSN system to have low and deterministic latency.

<<Is there anything else I must check in order to choose a PHY for TSN application?>>

A newer PHY that is 802.3br compliant, has a latency that is acceptable to your application, and I guess check that it supports the correct MDI and MII.

For reference, the i.MX93EVK uses a RTL8211.

Regards,

Clay