Low-cost Wi-Fi microcontroller. Predecessor to ESP32, popular for IoT.
| Pin | Name | Function | Type |
|---|---|---|---|
| 1 | GND | Ground | GND |
| 2 | GPIO2 | General I/O, boot mode select | I/O |
| 3 | GPIO0 | General I/O, boot mode select | I/O |
| 4 | RX | UART receive | BUS |
| 5 | VCC | 3.3V power | PWR |
| 6 | CH_PD | Chip enable, tie high to run | I/O |
| 7 | RST | Reset, active low | I/O |
| 8 | TX | UART transmit | BUS |
The ESP8266 is a low-cost Wi-Fi microcontroller with full TCP/IP stack capability, developed by Espressif. While it has fewer GPIO pins than the ESP32, it remains popular for simple IoT projects due to its low price and small footprint on the ESP-01 module.