External WDTV Remote Control Power Switch – Part I

Today’s project is external power control for the Western Digital WDTV.  Today we will design the circuit and generate the PCB using positive photoresist process.  Tomorrow we will develop the software for controlling the device.

The WDTV is a digital media player for all your (legally-downloaded, of course) media files.  And it’s fantastic!  It can play all the 7337est formats like MKV in full motion 1080i with nary a stutter.  It’s got HDMI output and a teeny tiny remote control, and coupled with a TB or so of storage, it’s a one-stop shop for watching all those MKV and divx home videos that you recorded in HD in 1959.

Fig 1 – The Majestic WDTV


Uh Huh.  Well at least the manufacturers (WD) found a good way to leverage themselves into the “internet” video realm a little deeper.  They must have surveyed buyers of their gigantic HDD’s and found that most users were filling them up with umm, err, “home movies” and “original audio recordings”.  I for example, have over 4000 hours of my own beat poetry and interpretive dance vids on mine.  You should come by and watch for a month or two!

Long story short, they realized that connecting one’s PC to one’s TV just to play said avi files was totally l4m3!  So they built a tiny linux box to suck data from a USB drive and blast HDMI out the other side, all for $99.  Freakin brilliant.  It works a treat, and with the genius of B-RAD, has been hacked as the day is long.

But it has one diabolically annoying (and inefficient) trait – it never powers down!  Pressing the power button just turns off the LED’s – redonkulous!  I’m guessing there are some pretty good design compromises that went along with this, namely:

  • You’d have to remember to cache the “paused” locations for all the in-progress videos.  Woo, really tough stuff.
  • It takes an ass-long time to boot up.  Hide your uglies through trickery, consumers are stupid!

Both fair reasons to skimp on a real power down mode, but it causes some problems of it’s own.

  • Wasted power.  The thing is always on, dissipating it’s 9W or so of electricity.  At that rate, the earth will be a crumbled shell in 40 billion years!!!  hehe
  • The real problem – It never disables it’s HDMI output, so automatic HDMI switches go to WDTV land and NEVER COME BACK!  Now you have to get off your lazy ass and go switch the HDMI swapper manually.  Horrors!

So we’ve decided to post a little EXTERNAL power swapper for the WDTV.  Or any other low-voltage device that you may want to control via an IR remote control.

Truth be told, a guy named Dex did this a long time ago.  And it’s an awesome hack.  But it requires busting open the box and splicing into it’s guts.  Which we usually support, condone, and lobby for till we’re blue in the face!  But in this case it’s a bit less of a pain in the ass to do it externally, and you get a bit more flexibility in unplugging the thing if you decide that you never want to power down your WDTV ever again.  And perhaps you could even reuse this little IR relay board for some upcoming Halloween prank or something!

And the biggest reason of all: It gave us an excuse to use our brand new liquid positive photoresist!  Yay!   This first part of the tutorial will deal with the circuit, and the construction and assembly of the PCB.  Part II will deal with the software for decoding the WDTV’s Remote Control IR stream and doing the power up/down sequencing.  Here’s a pic of the finished monstrosity, sans micro.

Fig 2 – IR Controlled Relay Board for WDTV Power Switching

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