ESP32-RTL8201F devboard

ESP32-RTL8201F-devboard

A simple ESP32 devboard with WiFi and Ethernet using the RTL8201F transceiver including an onboard USB-C-port for power, programming and serial console.

Design

The schematics are based on the esp-32-poe-dev project by @jorticus but using the ESP32-WROOM-32E module instead of a barebone ESP32.

This board is designed as a 4-layer PCB and is optimized for cheap assembly with JLCPCB. So using basic parts where possible and a custom ESP32-WROOM-32E footrpint so the minimum via-hole-size is 0.3mm.

Assembly

The boards were fully assembled by JLCPCB (except for the pinheaders). The necessary production files are included under pcb/jilcpcb.

In the first interation I chose the wrong 3.3V LDO and had to amnually swap those. The uploaded board- and assembly-files are already fixed.

Development using platform.io

Save the esp32-rtl8201f-devboard.json into the boards directory of your platform.io project. Creating the folder if it doesn't exist yet.

Select the board in your platformio.ini

[env:esp32dev]
monitor_speed=115200
platform = espressif32
board = esp32-rtl8201f-devboard
framework = arduino

Now you can #include <ETH.h> and call ETH.begin(); in your code. Check out the firmware-examples for more details.

Stability

The main goal was to have a more stable link than the onboard wifi and with packet-loss around .00003% in my test I think it's pretty stable.

Ethernet instability when WiFi/Bluetooth is enabled

Enabling WiFi or Bluetooth while Ethernet is running can make the Ethernet link unstable on this board. A working workaround is to force the RTL8201F PHY to 10 Mbit/s; once the wireless radios are disabled again, auto-negotiation can be restored to use 100 Mbit/s.

The snippets below use the Arduino-ESP32 3.2+ API. Older cores (including the 2.x core still used by some PlatformIO espressif32 releases) do not expose ETH.setLinkSpeed() or ETH.setAutoNegotiation(); use Arduino-ESP32 3.2+ or an ESP-IDF 5.x project if you need this workaround.

Force 10 Mbit/s before starting Ethernet:

#include <ETH.h>

void ethernetBegin10Mbit() {
  ETH.setAutoNegotiation(false);  // required before changing the speed
  ETH.setLinkSpeed(10);           // 10 Mbit/s, full duplex
  ETH.begin();
}

Restore auto-negotiation at runtime, for example after turning WiFi/Bluetooth off. This restarts the interface, so expect a short link drop and IP reconfiguration:

void ethernetUseAutoSpeed() {
  ETH.end();
  ETH.setAutoNegotiation(true);
  ETH.begin();
}

To drop back to 10 Mbit/s later, restart the interface the same way:

void ethernetUse10Mbit() {
  ETH.end();
  ETH.setAutoNegotiation(false);
  ETH.setLinkSpeed(10);
  ETH.begin();
}