For e-loading keypad setup, you need to add Arduino because ESP8266 boards have limited PINS. Just connect the Arduino's TX to ESP8266's RX. If they are on different power adapter source, link the module's ground. Please refer to Arduino for keypad for more information.

Supported ES8266 boards:

1. WEMOS
2. NodeMCU

2 ways to flash:

1. Using Android Phone With OTG
2. Using PC

Softwares to Download:

1. Install ESP8266 Loader
2. Download ESP8266 Firmware . Unzip the content of the zip file (esp8266-firmware-xxxxx.zip).

After downloading the needed softwares, connect the ESP8266 Board to your Android phone via OTG. Make sure you enable the OTG setting on your android.

Open ESP8266 Loader App and tap Allow on the permission prompts.

Then tap on the source item to select the esp8266 firmware.

Tap the green upload icon at the right to start uploading.