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 withArduino

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