Ethernet used as slave RMII ?

[Kawan31]

Hello,

Is it possible to use the ESP32 as a slave to another CPU having an RMII interface ? The 50MHz clock is specified as output and I didn't find any feature to return the interface behavior.

I would avoid an Ethernet switch just to connect an ESP32 and a Linux. ( we just need the ESP32 to forward an IP stream).

Another possibility is with SPI, like on ENC28J60. But we have to write quite a lot of code to do that.
By the way, using SPI there can be gret opportunities with Rapsberry zero : http://raspi.tv/2015/ethernet-on-pi-zer ... on-your-pi

Thanks.
Yves.

[WiFive]

Have you seen
http://www.esp8266.com/viewtopic.php?f=13&t=7053
https://hackaday.io/project/8678-rpi-wifi-hat
https://github.com/al177/esp8089

[martinayotte]

Oh ! that's look better, see some activity there !

(btw, I was one of the posters on the the first link ...)

At first, I was sceptical because esp8089 is a bit legacy and it is not known if esp8266 and esp8089 are equivalent.
And since it is Linux driver that upload firmware into ESP provided in eagle_fw*.h are still dated Dec 2014, I still have doubts.
What is this firmware ? Is it an older AT firmware previous than the ESP8266 one ?

If ESP32 can help there, the same firmware issue is there : how an old driver for esp8089 can be compatible with ESP32 ?

The is a big gap there to fill ...

[WiFive]

Basically esp8266 is esp8089 plus some extra features so using esp8266 in esp8089 mode just ignores those features. Same with firmware, it is just basic radio firmware, more basic than AT firmware. Just push raw data back and forth because Linux host is faster processing.

It has nothing to do with esp32, but in this mode the only reason to upgrade to esp32 would be for Bluetooth.

[Kawan31]

@WiFive, OK for ESP8266 = 8089 die with SDIO. But the ESP32 has nothing in common.
The ESP8266 is way to slow to replace a real WiFi interface.

4.9 chapter of the ESP32 datasheet states that the SDIO is HOST. So I don't see how I may reverse the clock either...

I'm quite sure someone will implement a fast SPI mode for Rapsberry+ESP32. Then we may be able to reuse it for other Linux CPUs.

I need a clean and supported way to interface the ESP32. SPI is one safe way to do it without doubts nor additional hardware.
RMII would have been the best (DMA+buffers). That was my question.

It would have been simple for Espressif to have a master+slave RMII in order to become a simple way to add WiFi to a lot of Linux environnements. Its not a the case. So we will see how to interface the ESP32 another way.

[WiFive]

Esp8089 can't be that slow if its used in android tablets and TV sticks. But yes esp32 supports higher data rates and faster interfaces. Most low cost android/Linux devices use one of the realtek or ampak modules.

[WiFive]

@WiFive, OK for ESP8266 = 8089 die with SDIO. But the ESP32 has nothing in common.
The ESP8266 is way to slow to replace a real WiFi interface.

Just want to update this guy got 40Mb/s performance from esp8266. https://hackaday.io/project/8678/log/29619-meet-v01

If 40Mb/s is still considered way too slow then you're right its the wrong chip.