Documentation

Overview

The TTGO T-Internet-POE puts an ESP32 on a wired network. It pairs the ESP32-WROOM-32 with a LAN8720A Ethernet PHY and 802.3af-compatible Power over Ethernet, so a single Ethernet cable can deliver both the network connection and the power. That makes it the right board for installations where Wi-Fi is unreliable or unwelcome: MQTT gateways, home-automation bridges, sensor nodes in metal enclosures, access control, and anything mounted far from an outlet.

You still get the full ESP32 feature set — Wi-Fi, Bluetooth, and a row of free GPIO for I2C, SPI, and UART peripherals — plus a microSD slot for logging. Firmware options include Arduino, ESP-IDF, and ESPHome, which supports this board's Ethernet configuration out of the box.

There is nothing to wire for basic use: plug in an Ethernet cable (PoE or not), or power it over USB-C via the programmer, and it is on the network.

At a Glance

Specifications

Getting Started

Networking needs no wiring — just an Ethernet cable. The part most people trip on is programming and the internal Ethernet pin map, so here is both:

1. Flashing firmware

The board has no permanent USB port; it is programmed through the small T-U2T USB-C downloader that clips onto the programming header. Plug the downloader in, select ESP32 Dev Module in the Arduino IDE, and upload as usual. Any 3.3V USB-serial adapter also works (TX/RX crossed, IO0 to GND during reset for bootloader mode).

2. Ethernet pin map (fixed on this board)

These four values are all your firmware needs — they appear in both code examples below. RMII also reserves GPIO 19, 21, 22, 25, 26, 27 internally; plan peripherals around the remaining broken-out pins (GPIO 34-39 are input-only on every ESP32).

Code Examples

Ethernet web client (Arduino)

// T-Internet-POE - bring up Ethernet and fetch a web page
// Board: "ESP32 Dev Module". Uses the built-in ETH library.

#define ETH_CLK_MODE  ETH_CLOCK_GPIO17_OUT
#define ETH_POWER_PIN 5
#define ETH_TYPE      ETH_PHY_LAN8720
#define ETH_ADDR      0
#define ETH_MDC_PIN   23
#define ETH_MDIO_PIN  18

#include <ETH.h>

static bool ethConnected = false;

void onEvent(WiFiEvent_t event) {
  switch (event) {
    case ARDUINO_EVENT_ETH_GOT_IP:
      Serial.print("IP address: ");
      Serial.println(ETH.localIP());
      ethConnected = true;
      break;
    case ARDUINO_EVENT_ETH_DISCONNECTED:
      ethConnected = false;
      break;
    default:
      break;
  }
}

void setup() {
  Serial.begin(115200);
  WiFi.onEvent(onEvent);
  ETH.begin(ETH_ADDR, ETH_POWER_PIN, ETH_MDC_PIN,
            ETH_MDIO_PIN, ETH_TYPE, ETH_CLK_MODE);
}

void loop() {
  if (ethConnected) {
    Serial.println("Ethernet up - board is on the LAN");
    delay(5000);
  }
}

ESPHome configuration

# ESPHome config for the T-Internet-POE
# Drop into your device YAML - no wifi: block needed.

esphome:
  name: t-internet-poe

esp32:
  board: esp32dev

ethernet:
  type: LAN8720
  mdc_pin: GPIO23
  mdio_pin: GPIO18
  clk_mode: GPIO17_OUT
  phy_addr: 0
  power_pin: GPIO5

api:
ota:
  platform: esphome
logger:

Frequently Asked Questions