Mature and stable ESP-12F WiFi module onboard with 4MB flash capacity. The I/O port and UART program download port for the WiFi module are all led out to facilitate secondary development. Power supply mode supports DC12V. Features a reset button and a programmable button for the onboard WiFi module. ESP-12F supports development tools like Eclipse/for Arduino IDE, and reference programs are provided for the Arduino development environment. Onboard 16-channel 24V/10A relay, output signal suitable for controlling loads with working voltages within AC 250V/DC 30V. Includes onboard indicator LEDs for power, relay status, and module activity. Two onboard shift registers (74HC595) control the relay switches. The 16-way relay is controlled by two cascaded 74HC595s, so the corresponding control program for the 595 is needed to open and close the relay. A reference program has been provided. Burning and writing port: GND, Rx, Tx, and 3.3V of ESP8266 are respectively connected to the GND, Tx, Rx, and 3.3V of an external TTL serial port module. IO0 must be connected to GND during download, and then IO0 and GND should be disconnected after download. Relay output terminal: NC: Normally Closed end, the relay is shorted with COM before de-energization and disconnected after de-energization; COM: Common end. NO: Normally Open end, the relay is disconnected before energization and shorted with COM after energization. Color: Green Material: Plastic Package Contents: 1 x Development Board (Only the above package content is included; other products are not.) Note: Light and different displays may cause the color of the item in the picture to be slightly different from the real thing. The allowed measurement error is +/- 1-3 cm.