ESP8266-04 Economic Wifi SMD

ESP-04 module (external connection) is one of the smallest ESP8266 boards. Its size is about 12.5x14.5mm. It is a Surface Mount Technology (SMT) module with 2mm pin pitch. The module has no built-in antenna.

Seven GPIO pins are reserved: GPIO0, GPIO2, GPIO12, GPIO13, GPIO14, GPIO15, GPIO16.

ESP- 04 has an output to the external antenna, it is one of the outermost pins. However, it does not have a GND pin on the side, so connecting the coaxial antenna cable can be difficult.

Features:

Uses LWIP
802.11 bgn
WIFI Direct (P2P), SOFT-AP
Built-in TCP/IP
AT command is perfect, efficient, concise
Supports three modes: AP, STA and AP + STA coexistence mode