ESP-WROOM-02 is a 32-bit low power micro-controller (MCU) Wi-Fi Module that integrates TCP/IP network stacks, and includes 10-bit ADC with HSPI, SDIO, UART, PWM, I2C, and I2S interfaces. The module is highly integrated. It consumes extremely low power while providing wireless internet connection for embedded devices. It can be easily integrated into resource-limited devices due to its small form factor of only 18mm x 20mm.
In addition to the ESP8266EX chipset, the module also integrates an SPI flash with 32Mbits capacity, along with a SOP8-150mil package. The SPI flash is incredibly useful for storing user programs and firmware.