• ESP8266 offers a complete and self-contained Wi-Fi networking solution, allowing it to either host the application or to offload all Wi-Fi networking functions from another application processor.
• When ESP8266 hosts the application, and when it is the only application processor in the device, it is able to boot up directly from an external flash.
• It has integrated cache to improve the performance of the system in such applications, and to minimize the memory requirements.
• Alternately, serving as a Wi-Fi adapter, wireless internet access can be added to any microcontroller-based design with simple connectivity through UART interface or the CPU AHB bridge interface.

The D1 is an Arduino Uno-like wifi board based on ESP-8266EX.

• 11 digital input/output pins
• 1 analog input(3.3V max input)
• A Micro USB connection
• A power jack, 9-24V power input.
• Compatible with Arduino

Specifications: 

• 802.11 b/g/n
• Integrated low power 32-bit MCU
• Integrated TCP/IP protocol stack
• Integrated TR switch, balun, LNA, power amplifier and matching network
• Integrated PLL, regulators, and power management units
• Supports antenna diversity WiFi 2.4 GHz, support WPA/WPA2
• Support STA/AP/STA AP operation modes
• Support Smart Link Function for both Android and iOS devices
• SDIO 2.0, (H) SPI, UART, I2C, I2S, IR Remote Control, PWM, GPIO
• STBC, 1×1 MIMO, 2×1 MIMO
• A-MPDU & A-MSDU aggregation & 0.4s guard interval
• Deep sleep power < 5uA
• Wake up and transmit packets in < 2ms
• Standby power consumption of < 1.0mW (DTIM3)
• 20 dBm output power in 802.11b mode
• FCC, CE, TELEC, WiFi Alliance, and SRRC certified

• Board Dimensions: 68.6mm x 53.4mm (2.701″ x 2.102″) / Long x Wide
• Weight: 21.8g (0.769oz)