Which Ethernet PHY to choose for STM32 ethernet applications?

[Broman3100]

I'm developing my first STM ethernet application and want to use it's built in MAC, from my understanding any 10/100 ETH PHY with MII or RMII should work but there's such a big list of those on market, ST Disco boards I found use LAN8740, which is expensive and somewhat hard to obtain, some tutorials I saw used LAN8720, KSZ8xxx.

My main concern is if there is a big difference I'm missing out or will any of these products work same? Any experienced dev input would be appreciated on which of these IC-s is more recommended over the others.

#Edit: I was planning on using F107 for it but now memory has become a concern, if anyone has a general idea of how much memory ethernet libraries usually take up, I'd love to know it.

[LCE]

Right now the biggest problem seems availability.

I think most Nucleo-boards are using the LAN8742A, I do so too on a board still in development (but doing good so far on the HW side).

I see no reason for using MII instead of RMII, as you're havin HF stuff on your PCB anyway, but maybe there's something I don't know.

[SanuzR]

About memory, you can evaluate. But you can check DP83848.

[Broman3100]

It does really seem like most of the phys I checked, including the two you guys suggested are out of stock or overpriced on most retailers, Does it boil down to whatever PHY I can get my hands on? The code part should be basically same for all of them right? (except the initialization)

[Pavel A.]

Do you have none other requirements to the PHY? Just the plain vanilla 10/100 RMII?

Then get whatever is available and ask the vendor how to connect it to STM32.

[Piranha · Accepted solution]

Your understanding ir correct. While a feature set differs, almost any part with MII/RMII interface will work. Regarding the software, for the basic functionality the only thing that differs is a register address and positions of two bits, which indicate the speed and duplex mode selected by auto-negotiation.

DP83848 is pretty old. Nothing wrong with it, but never designs are typically better and/or cheaper. Most of ST's non-expensive boards use LAN8742A, which is a nice part. But at this point I would recommend the DP83825I - pretty advanced, small, cheap, a new design and available.

From STM32, if possible, I would avoid F1 and use at least F2 series.

Regarding memory usage read my post in this topic:

https://community.st.com/s/question/0D53W00000V22nISAR/microcontroller-requirements-to-implement-an-embedded-web-server-using-websocket-js-and-html5

[Broman3100]

Thanks for you response, that was very informative!

[DTomi.1]

Do you maybe have an example driver using the DP83825I?