Playout & Transmission Global Viewpoint – February 2020

Long Live The GPIO

The humble GPIO has been a central part of many broadcast infrastructures for as long as there has been the need to provide control. It’s probably the simplest form of communication and is responsible for triggering a whole plethora of live on-air events. But with the introduction of the NMOS-07 specification, have we seen the end of the GPIO?

Whether operating a relay closure or lighting a LED, GPIOs have stood the test of time. They are easy to use, provide automated voltage level translation, and are relatively simple to install. There are even vendors who have made interface units that translate GPIOs and provide logical conditional programming for advanced event triggers.

So why would we ever want to go down the NMOS-07 path? To me, the clearest advantage is flexibility. NMOS-07 transfers over IP/Ethernet, leading to simpler systems that are easier to program and install. No soldering D-Type connectors and burning the ends of your fingers, and no need to crawl around the back of racks with your voltmeter trying to find intermittent connections.

NMOS-07 is designed to provide a mechanism to carry time-sensitive information including camera tally’s and push button information. A bespoke panel needed to operate system-critical equipment can now work over the broadcasters’ network without the need for dedicated wiring and Krone blocks. Any event can be programmed and if the software is written correctly, users can design their own solutions through either a GUI interface or XML-type configuration file.

This all sounds incredibly exciting. However, I believe there are challenges we must consider based on the fact that broadcasters demand order. In my view, flexible systems are the future but with flexibility comes the potential for chaos. For example, how do we document NMOS-07 messages? And how do we test to know if they’re working?

Without hardwired cabling and traditional system diagrams it can be difficult to get a picture in our heads of how an infrastructure works. Networks, by definition, are mesh based and the point-to-point connections largely disappear. In other words, how do we provide documentation? I suppose this question applies to all aspects of IP systems in broadcasting. There’s always the possibility that I’m expecting too much and in this new flexible world we no longer need a “system in our heads”.

With IP networks and computer systems, monitoring NMOS-07 events becomes much easier. But it’s important that the message generating and receiving devices have easily accessible logs. Dedicated monitoring equipment combined with a bit of network programming has the potential to monitor and log all NMOS-07 messages in a broadcast infrastructure.

I’m a great advocate of the new world of flexibility and the opportunities for NMOS-07 are immense, but there’s something to be said for the solid clunk of the GPIO relay. A bit like the reassuring clunk the airplane landing gear makes as it lowers into safe position for arrival in Vegas. Flexibility provides great opportunity, but we must be mindful of the need to maintain order, so let’s not write off the humble GPIO just yet, it’s served us well, and will continue to do so.

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