All the functions of the WiFi Module are managed by the powerful system on chip (SoC) ESP8266, that combines a 32 bit micro-controller (and many peripherals, such as GPIO, I2C, ADC, SPI, PWM) with a WiFi radio.
|RST||External reset signal, active low||MOSI *||MOSI for SPI interface|
||10-bit ADC Analog Input 0-1V||SCLK *||Serial Clock for SPI interface|
|CHIP-EN||Chip Enable, active high||GND||Power Ground|
|GPIO16||General Purpose I/O||GPIO15||General Purpose I/O|
|GPIO12||General Purpose I/O||GPIO2||General Purpose I/O (connected to the LED)|
|GPIO13||General Purpose I/O||GPIO0||General Purpose I/O|
|VCC||+3.3V power input||GPIO4||General Purpose I/O|
||Chip Select for SPI interface||GPIO5||General Purpose I/O|
||MISO for SPI interface||RX||UART RX|
||General Purpose I/O (only on 12-D version)||TX||UART TX|
|GPIO10||General Purpose I/O (only on 12-D version)|
* Not managed from miuPanel firmware.
||(GPIO2)||Connected to GPIO2|
After power-up (or reset) the module can boot in two different modes, depending on the logic levels applied on pins GPIO0 and GPIO2 and GPIO15:
This module requires 3.3 V on VCC and 3.3 V for the logic. It does NOT tolerate 5 V!
If you use Arduino UNO, and you connect to the Wi-Fi module the RX and TX pins of Arduino, you will destroy the module.
Moreover, the 3.3 V source of Arduino Uno has inadequate current capability to power this module. You should use a separate 3.3 V source to power the module, with a current capability of 300 mA or higher, because the average current consumption of the Wi-Fi module is about 140 mA.