An explanation of the ESP8266's ADC characteristics: 10-bit resolution, a single pin, and the voltage range difference between NodeMCU and the bare chip.
Building an SMS-controlled switch for a 12V lamp using a SIM900 shield and a relay, parsing ON, OFF, and STATE commands.
An explanation of ESP32's PWM architecture via 16 independent channels and the ledcSetup/ledcAttachPin/ledcWrite functions, compared to traditional analogWrite().
Wiring a 16x2 LCD fitted with an I2C backpack to ESP32 using just two wires, via the LiquidCrystal_I2C library.