This adapter is designed to work with the ESP-12 (ESP-07 or other equivalent WiFi Modules) and permit to power supply the module with a 5V source and to interface the module directly to a 5V logic.
The module also performs the action of level shifter for serial pins from 5V to 3.3V so it is possible to interface it directly to the TX and RX pins of your microcontroller with 5V logic in complete safety.
No other external components are needed, because the ADP-12 already has all the necessary components to turn on the module in the “RUN” firmware mode (including some pull-up resistors for the lines GPIO0 and GPIO2).
Only 4 wires are needed to power and communicate with the module.
The ADP-01 also allows you to easily insert the module on breadboard and you need only 4 wires to power and communicate with the ESP-12 module. In fact it is enough to connect the power supply (to 5V and GND pins) and 2 serial communication pins (TX-> RX and RX-> TX).
There is also a protection diode against reverse polarity errors on the power supply pins.
If you want to reprogram the ESP8266 chip with another firmware, just connect pin 0 of the ADP-12 to GND and turn the power off / on again. In this way the module will enter in “programming mode”.
WARNING: do not use an input voltage higher than 5.5 V to avoid burning the ADP-12.