ESP-01 module requires 3.3V power and USB to serial converter. Arduino UNO acts as serial bridge between ESP and computer. RX pins need voltage divider to prevent damage
Interrupts detect GPIO state changes without constant checking. AttachInterrupt() function sets interrupt pins, ISRs, and modes. ISRs must have ICACHE_RAM_ATTR attribute. Three interrupt modes: CHANGE, RISING, and FALLING
ESP8266 12-E chip has 17 GPIO pins. Not all GPIOs are accessible in all development boards. GPIO numbers don't match board silkscreen labels
Latest version of Arduino IDE must be installed. Add ESP8266 add-on URL to Arduino IDE preferences. Install ESP8266 Community add-on through Boards Manager
MIT App Inventor enables creating Android applications for home automation. Project uses NodeMCU ESP8266 and relay module for control. App can be downloaded via QR code or APK file
LoRa operates at 433-916 MHz frequencies with 3000-8000m range. Features FEC Forward Error Correction for improved reliability. Supports data compression to reduce transmission time. Operates at 410-441 MHz frequency with 32 channels