I solved two ‘problems’ this week: adding remote power-on capability to my home theater PC (HTPC) and remotely switching input selections on an HDMI switch box — by reassigning a couple of unused buttons on our TV’s remote control.
My HTPC (the computer in my TV cabinet) is in a slim CoolerMaster case, which had remote power-on capability via its own remote control. The infrared receiver broke long ago but that was no biggie — I just got off my arse and turned the computer on manually and then operated it with my Rii mini keyboard/mouse.
Recently, I added an HDMI switch to my set up because my aging Samsung telly has only one HDMI input. The switcher doesn’t have a remote control, so I found myself making the arduous 1.5 metre excursion across the living room far too often. The time had come to be rid of all that pesky incidental exercise by way of an Arduino project.
I started with an infrared receiver module connected to an Arduino nano. The IR receiver both detects and decodes remote control signals, presenting the Arduino with nice, easy to work with codes. A temporary set-up of Arduino and IR receiver enabled me to record the codes associated with the buttons I wanted to use on the TV remote control and then it was time to build the main project.
Most Windows-based PCs are turned on by briefly connecting the green wire on the power supply to an earth or ground point. For this project, I piggy-backed this green wire to an Arduino output — which is either ‘high’ (5 volts) or ‘low’ (grounded). By switching that output from high to low and back again the PC will start.
My HDMI switch doesn’t lend itself to an electronic remote control solution, so I had to mechanically press the button the same way I did with my remote camera shutter release — a servo. Unlike that project, there is no need to calibrate the servo every time because it’s a more permanent set-up. What you see in the pictures is my proof-of-concept — I hope to make something more elegant one day.
To make this project useful it has to remain active, even if the PC is turned off. This was fairly easy to solve as PCs have 5 volt standby power that is always available. In this case the standby power had already been tapped for the original remote control detector circuit.
The Arduino nano is tiny so I had no issue fitting it into the computer’s case, and the IR detector just replaces the old dead one. The components I used in this project all came from one of those cheap Chinese super-sites and cost less than A$5 — a very inexpensive solution.
Altogether, less than a day of tinkering, testing and fitting it up. No additional remote controls. More couch time. 😉
A brief outline of the schematics and Arduino code can be found on the Infrared remote – technical guide page.