What is PHY as it relates to ESP32?

[kolban]

I've been coming across the concept of "PHY" from time to time in my ESP32 studies. Can someone help me to understand what is meant by that term/concept in ESP32?

I see in "make menuconfig"

we have a component config called "PHY" which contains:

• Initialize PHY in startup code
• Use a partition to store PHY init data
• Max WiFi TX Power (dBm)

but I haven't yet seen a description of what we mean when we say "PHY".

[WiFive]

https://en.m.wikipedia.org/wiki/PHY_(chip)
https://en.m.wikipedia.org/wiki/Physical_layer

Basically the radio hardware and its driver code

[kolban]

Thank you sir ... if I understand correctly, PHY is the layer in ESP32 (hardware and software) responsible for the physical layer of network communications ... likely to include radio for WiFi and BT and possibly Ethernet.

If we now look at the ESP32 specifically, we see that it has configuration properties ... for example:

Initialize PHY in startup code - What is a potential use case where we would not want the PHY layer initialized? What are the implications of manually initializing it?

Use a partition to store PHY init data - What is considered to "be" PHY init data? Is there anything there that we might want to customize? If we leave this in its default value of "off", where is PHY init data coming from? (I am assuming "PHY init data" is control data that describes the operation of the physical layer... that then begs the question ... what are the "attributes" and "characteristics" of that data).

[WiFive]

What is a potential use case where we would not want the PHY layer initialized? What are the implications of manually initializing it?

If you aren't ready to use the radio and want to save power. If you want to set calibration mode.

Use a partition to store PHY init data - What is considered to "be" PHY init data? Is there anything there that we might want to customize? If we leave this in its default value of "off", where is PHY init data coming from? (I am assuming "PHY init data" is control data that describes the operation of the physical layer... that then begs the question ... what are the "attributes" and "characteristics" of that data).

It is not thoroughly documented, but here.