Output Devices

In autonomous (not requiring any human intervention) Physical Computing and IoT systems the output from the processor is in the form of control signals to devices to take some action. There may be scenarios where you need to also provide output to be viewed by humans. The output devices listed below provide indicators or present data to be viewed by humans.

LEDs

There are two types of LEDs: single-color LEDs and RGB LEDs. While single-color LEDs can emit any one color, RGB LEDs can emit multiple colors. Single-color LEDs have two leads, positive (anode) and negative (cathode). RGB LEDs have fours leads. They can have a common cathode (negative lead) or a common anode (positive lead) and correspondingly three positive or negative leads, one for each of the primary colors (Red, Green, and Blue). By varying the power of the signal supplied to the RGB leads multiple colors can be emitted.

Buzzers

Piezoelectric effect is the ability of certain materials to generate an electrical charge when subjected to mechanical stress, such as pressure. A piezo buzzer works on the inverse piezoelectric effect, where applying an electrical voltage to a piezoelectric ceramic material causes it to vibrate and produce sound waves.

Buzzers can be an active, buzzing at a predefined frequency when a steady DC voltage is applied, or passive producing varied tones from an oscillating input signal.

Liquid Crystal Displays (LCDs)

An LCD is a flat-panel display that uses the light-modulating properties of liquid crystals, using a backlight or reflector to produce images in color or monochrome. LCDs can either have a backlight as the background with black lettering or a black background with the letters with the backlight.

LCDs are used in various applications, including LCD televisions, computer monitors, instrument panels, aircraft cockpit displays, digital cameras, and indoor and outdoor signage.

Organic Light Emitting Diodes (OLEDs)

An OLED is a type of light-emitting diode (LED) in which the emissive electroluminescent layer is an organic compound film that emits light in response to an electric current. This organic layer is situated between two electrodes, at least one of these electrodes being transparent. OLEDs are used to create digital displays in devices such as television screens, computer monitors, and portable systems such as smartphones and handheld game consoles.