MHL… no weak link
As the number of mobile devices in the smart home grows, it’s important for integrators to understand the benefit of making the link from phone to display. Paul Skelton reports.
In relatively recent years, you may have come across a port on some consumer electronic devices marked ‘MHL’ (or ‘HDMI/MHL’) and thought: “What the hell is that?”
MHL, or mobile high-definition link, is a communications protocol designed to connect a mobile device to a display or monitor while maintaining high definition audio and video transmission.
ADVERTISEMENT
“When we released the first MHL specification, we started with a simple idea of connecting a phone to a TV. This has now evolved into an advanced world of connectivity,” MHL, LLC president Rob Tobias says.
“Our product ecosystem has rapidly grown and the use cases continue to expand, making MHL the world’s most widely adopted mobile TV-out standard and the de-facto connectivity between mobile, consumer electronics and automotive products.”
The MHL specification was first published in 2010 and the first devices began shipping in 2011. Recently, MHL, LLC – the organisation founded to guide and foster the standard – announced that more than 650 million MHL-enabled devices have shipped, including phones, TVs, tablets, AVRs, Blu-ray players and in-car entertainment systems.
It would appear that a large ecosystem of MHL products is now firmly entrenched in living rooms around the world.
In August 2013, MHL, LLC announced an updated MHL 3.0 specification, which uses a bi-directional channel that’s significantly faster than MHL 2 and enables concurrent 4K video and high-speed peripheral support of mass storage and input devices such as a touch screen, keyboard and mouse.
The MHL 3.0 specification capabilities include:
- Support of 4K formats up to 2160p30.
- Simultaneous high-speed data channel.
- Improved Remote Control Protocol (RCP) with support for peripherals such as a touch screen, keyboard and mouse.
- Power charging up to 10W.
- Backward compatibility with MHL 1 and MHL 2.
- Latest HDCP 2.2 content protection.
- Enhanced 7.1 surround sound with Dolby TrueHD and DTS-HD.
- Connector agnosticism – uses as few as five pins.
- Support for simultaneous multiple displays.
Now, MHL, LLC has developed an MHL Alternate Mode (‘Alt Mode’) for the USB Type-C specification.
Using the MHL Alt Mode, a USB Type-C connector and cable can support the updated MHL 3.2 specification, which includes 4K video, multi-channel surround sound audio, HDCP 2.2 and is backward compatible with existing versions of the MHL specification.
“MHL Alt Mode enables a USB Type-C connector to support the MHL 3.2 specification, which includes 4K video, multi-channel surround sound audio and HDCP 2.2,” Rob says.
“This benefits consumers and systems designers because a single connector reduces costs and increases functionality.”
Part of MHL’s success comes from its support of popular connectors already present on mobile devices and displays, as well as proprietary connectors, Rob says.
“The dominant connector on mobile devices is micro USB but it was designed a long time ago, long before smart phones were invented.
“This means it has some limitations: it only has five pins, it can only carry a certain amount of power and it’s unidirectional.
“USB Type C is a reversible connector, so it’s a lot more user friendly from that perspective. It also carries a lot more power and it has 24 pins. So it makes sense that this will become a popular connector type, which is why we’ve ensured that MHL will work with it.”
Mobile devices designed with a USB Type-C receptacle and built to support the MHL Alt Mode will be able to connect to any MHL TVs, monitors, AVRs, Blu-ray Disc players, projectors, set-top boxes and automotive products using USB Type-C to HDMI Type A MHL cables.
Mobile devices with USB Type-C MHL Alt Mode can also connect to HDMI legacy displays using adapters that support MHL-to-HDMI protocol conversion.
“MHL is technology designed to be connector agnostic, so we can easily adapt to emerging connector technologies.
“We made sure the new Alt Mode supports all the legacy devices out there, so you’ll be able to connect it to your MHL displays, and we made sure it supported concurrent MHL audio and video with the USB functions and power charging.”
-
ADVERTISEMENT
-
ADVERTISEMENT
-
ADVERTISEMENT
-
ADVERTISEMENT