Media Interfaces (Aux, HDMI, Thunderbolt)

AUX: The Original Auxiliary Port

An auxiliary port, or AUX, is a standard communication port on a device that allows for the connection of audio signals. This port is typically used for headphones and headsets, microphones, speakers, and other audio devices, including some traditional audio technologies. When you connect these to a primary device, except for certain USB setups, you're usually using an auxiliary port.

On a traditional PC, the first computer port (COM1) is often set up as an audio auxiliary port. This is the initial serial port with a predetermined assignment for serial devices. RS-232 standardization is applicable to various PC audio attachments, many of which are converted to the 3.5mm or "1/8 inch" standard audio jack on much peripheral hardware. Using these audio ports often requires different types of adapters and fittings for backward compatibility as system components evolve from various manufacturers.

To understand how this system worked on traditional PC platforms, consider the general design for system resource configurations on a PC. Designers have designated each port as COM1, COM2, COM3, COM4, etc. Each COM location had an interrupt request (IRQ) address and input/output (I/O). The IRQ address is a signal sent from a device to the CPU indicating an event, like an audio signal starting or stopping.

Auxiliary ports and jacks are crucial for digital music, whether through external speakers or directly from a device. This has made the auxiliary jack extremely useful to smartphone users, where the single auxiliary jack lets you play music through headphones, watching movies or TV shows with high-quality audio directly or participate in conference calls through a headset.

However, in 2016 Apple removed the conventional auxiliary port from newer iPhone models, requiring the purchase of specialized headsets and other equipment. Despite Apple's defense of this move, it was unpopular with many users and remains an example of unexpected interface issues created by the manufacturer. Other companies followed suite, removing the interface across their products.

As many standard auxiliary ports are becoming obsolete, companies are finding ways to make new systems backward-compatible with older devices. Another significant design change is the integration of input devices and peripherals into primary devices, such as the transition from USB-connected webcams to built-in laptop cameras, and the shift from traditional mice to trackpads and touchscreens. The use of auxiliary ports is decreasing as there are fewer peripheral devices to connect them to, and this trend appears set to continue.

HDMI: High Definition Media Interface

HDMI is how Raspberry PI camera devices transmit uncompressed data from the sensor to the main board. It uses the extremely common ANSI/CTA-861 standard, and has a number of iterations since it first came out in 2003. It supersedes and is backwards compatible with DVI, Digital Video Interface. This is not an open source protocol, and HDMI requires licensing to use. Multiple standards exist: the standard type (A), the dual link type (B), and the mini and micro configurations (C and D). OasisX products use type A connections.

This protocol is also used to transmit data between a multitude of consumer devices, and enables the CEC, or Consumer Electronics Protocol. The CEC allows one user to control up to 15 connected devices using one controller. A common example is controlling a TV, a sound system, and a disk player using one remote control system. HDMI replaced the R-G-B color format with Y’-CB-CR. Y’-CB-CR is a method used to describe visualized colors based on color space. Y’, Y prime, represents luma, the brightness of an image. CB and CR are blue-different and red-difference color components. These signals have much more fidelity and less redundancy than prior RGB methods.

HDMI continues to be a widespread, popular protocol in consumer electronics across the globe, and will likely remain popular for the forseeable future. It is highly compatible with multiple standards and easily employed in many applications. HDMI’s longevity-over 21 years now-has cemented it within consumer electronics, and it is second after USB in common wired data transmission.

Thunderbolt: Media Over USB

Thunderbolt is another of the transmission protocols underpinning most daily consumer electronics that connect hardware to a computer. It debuted in 2011 with Apple’s MacBook Pro, replacing the august FireWire protocol, but did not truly enter the mainstream until iteration 3.0 aligned with USB standards. Since then, there have been two more iterations of Thunderbolt, with the most current standard-5.0- aligned to USB4 2.0 specifications. Thunderbolt 5.0 was released in 2024.

Thunderbolt 3.0 marked the start of popular adoption; since it matched the form factor of USB-C and was able to deliver power, it was now broadly applicable to multiple other peripherals and was no longer confined to Apple products. The resolution of intellectual property issues and the opening of a broader standard allowed for broader employment, especially after 2020 when Intel opened up the protocol for further use. Intel currently retains control over the certification process for Thunderbolt devices, however.

Today, Thunderbolt has arrived as the backbone of combined media and power transmission methods. This standard has driven improvements in hardware development, software integration, and format unification across technology manufacturers for their end users. Over a decade of unifying work has constructed the pillars of a combined data and power transmission capability. Pushing roots through various platform’s walled gardens, Thunderbolt became an infrastructure for device connection that that has become ubiquitous the world over.

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