• forum thread about iPhone charging
• Control an Arduino with an iPhone

• Arduino source files / programs are referred to as sketches sketches are generally saved in the below location

$HOME/$USER/Documents/Arduino

• Logic level - is a set voltages at which a device communicates. A common logic level is 5V, and newer logic levels work at 3.3V and 1.8V
• PWM Pulse Width Modulation - is used for Digital to Analog signal
  • PWM - Examples
    • the brightness of an LED
    • to vary the speed of the fan

digital resolution

• YouTube - Analog & Digital Signals

• LED’s are directional the shorter pin goes to GND.