Teardown and Design

The Hue Bridge has two screws that you need to remove before you can pop off the back. Even with the screws out, popping the back off is tricky—it has an interesting snap-in mechanism. Here’s what the back looks look like; the two white “feet” at the bottom are covering the screws. I used tools from iFixIt to get this open.

Once you open it up, you can see the back side of the PCB, and the snap-in connecter I mentioned earlier.

The PCB is connected to the front of the Bridge using a ribbon connector. This cable provides the power and signals for the LEDs and the Link button.

The main PCB has the two primary components of the Hue Bridge, an ST Microelectronics STM32F217VE Microcontrollerand a Texas Instruments CC2530 ZigBee Controller.

There is also an RF range extender (CC2590) coupled to the CC2530. The STM MCU has an integrated Ethernet controller, but as a whole the design has very few components. It’s clear that the majority of the cost for the Starter Pack is in the bulbs and not in the Bridge. (Based on the total kit price, the Bridge is $20 more than the cost of the three bulbs, though of course that leaves plenty of room for profit margins.) The image below shows the antenna for ZigBee:

I’ll cover the technology behind the Hue Bridge in a moment, but the choice of microcontroller for this design is a clear indication that this is primarily a purpose-built device. That is, it does not have the horsepower to extend to different types of applications due to the limitations of the CPU and the amount of memory. Nonetheless, it is well suited for the function at hand; let’s look at the specifics of the technology behind Hue before we get into a discussion of what it can and cannot do.

Philips Hue Setup Technology
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  • melgross - Friday, March 1, 2013 - link

    I began moving to compact fluorescents a couple of decades ago, and now I'm moving to LEDs. Until recently, LEDs have been too expensive ($125 for a 450 lumen bulb), but have dropped considerably ($30 for an 800 lumen bulb). One problem was that the brightness of LED bulbs weren't really known because standards weren't there, or being followed. I'm now finding that they are.

    I've experimented with a lot of these over the years, including naked chips up to 100 watts (vast light output, but terrible color, and requiring a massive heatsink. Which reminds me, the reason why these bulbs weigh so much is because of the heatsinks. That rear portion of the bulb is an aluminum casting, which you can tell by tapping on it. LEDs do get very hot. It's the lack of infrared light in the output that keeps LED light cool. But the LEDs need a sink for the self heating they undergo (a major reason why OLED phone screens are so dim. The hotter an LED gets, the shorter the lifespan, and OLEDs can't run nearly as hot as can these silicon, carbide, etc. models can.)

    But one disappointing part of this review is the lack of information as to the output of these bulbs. ARsTechnica also did a review of these some months ago. I don't remember if they said what the output is. Without knowing that, it's difficult to know how useful these are. For some people, dim rooms are fine, but for others, the room must be bright. So what are these equivalent to? Are we getting 400 lumens, 500, 600?
    Reply
  • BravoRomeo - Sunday, April 7, 2013 - link

    Philips specs the Hue at 600, depending on color temperature. Supposedly it derates itself if it gets too hot, so you might loose some brightness in a poorly ventilated fixture.

    I found the Hue bulbs comparable to a 60W GE Reveal incandescent. In fact, it was able to tune the color of Hue to exactly match the Reveal bulb, but without the heat... All you do is shift the hue a notch or two towards red/yellow and away from green, and a touch less saturated, which is what the filtering on the Reveal bulb does. Very impressive.
    Reply
  • foxalopex - Friday, March 1, 2013 - link

    I've bought a few LED bulbs over history and they've impressed me. They're definitely the next generation compared to compact fluorescents. They turn on instantly and you never have to worry about breaking the bulb if you turn it on and off a lot. Granted there are some problems too. Cheapo LED bulbs like the ones you can get from Walmart sometimes have the problem of the ballast dying if used for a long time. I have some expensive ones too and they've worked great except for slight FM radio interference. They're also horrifically expensive but that's not a surprise since the LED components are pretty pricy. Still I think it's just a matter of time. Reply
  • JeffFlanagan - Friday, March 1, 2013 - link

    Changing colors don't seem very useful unless the user is on LSD, but being able to red-shift home lighting after sunset could be very helpful for people who have trouble sleeping.

    Installing f.Lux on my PC to dim and redden the screen at night has greatly improved my ability to fall asleep, and I'd like to do the same with all my lighting.
    Reply
  • halbhh2 - Friday, March 1, 2013 - link

    "not to mention compared to incandescent lights you’re already cutting power use per light by about 55W, so it should come out as a large net savings..."

    'should' ??

    Not.

    Why did the reviewer stop there, without doing the very easy math?

    Perhaps because the real cost comparison is the *opposite* in reality.

    For instance, you might run 10 bulbs an average of 10 hours a day 365/year, saving about $200 on electricity in 1 year vs. incandescent.

    And incandescent is *not* even the competition here, since most households run a mix of bulbs which include numerous compact flourescents. That's the real comparison.

    In other words, the opposite conclusion is more valid: instead of a "large net savings" expect a *significant net cost*.

    And that's fine if you really want these. Just don't fool yourself into thinking you are saving money.

    Shame on the reviewer.
    Reply
  • JarredWalton - Friday, March 1, 2013 - link

    Full quote instead of your ellipses:

    "For the Starter Pack and three bulbs, you’re looking at around $1 per year, not to mention compared to incandescent lights you’re already cutting power use per light by about 55W, so it should come out as a large net savings (though not compared to running non-connected LED lights everywhere)."

    Obviously, we could have listed CFLs along with LEDs, but that's not the point. The point is whether the additional power draw incurred by the use of ZigBee (home automation) is a concern, and the answer is that no, it's not. Compared to CFL (14W), even running 24/7 for a year you'd only be spending an extra $7-$8 per light. If you can get the CFL for about $2 compared to $60, you might break even over the life of the bulb but probably not. But then, a $2 CFL doesn't offer the colored lighting options or home automation, which is the main attraction here.
    Reply
  • halbhh2 - Friday, March 1, 2013 - link

    Ok, but I just did not read it that way, and I'm not a poor reader. Perhaps you should clarify the text, so that it doesn't give the wrong impression. Reply
  • Qwertilot - Monday, March 4, 2013 - link

    Surely the energy use should be a concern?

    Its seemingly 0.4 watt continous vs 5 watt for the actual bulb, so if the light bulb is on for an average of two hours a day you've just *doubled* its yearly power usage. For many bulbs it'll be worse than that.

    While the overall amounts aren't massive it really does seem to be horribly gratitious.

    If this is going to scale out to whole houses/lots more devices then it badly needs some way to power the radios almost entirely off when not required. Some master controller device and a mode where they poll every minute or something.
    Reply
  • darkcrayon - Wednesday, March 6, 2013 - link

    You could help save energy with them in other more unusual ways... I have mine set to turn off automatically when I leave my apartment which guarantees I can never leave them on by mistake - Using a proximity app that senses if my iPhone is in range. And my hallway light comes on to greet me when I get home after a certain hour. Of course, running a server to handle that easily negates that power difference (of course the server is for a myriad of other purposes and not just for home automation control). Reply
  • glugglug - Tuesday, March 5, 2013 - link

    > And incandescent is *not* even the competition here, since most households run a mix > of bulbs which include numerous compact flourescents. That's the real comparison.

    Which brings up what for me is the main flaw in this product.

    The bulbs are type A (LED approximation of a standard light bulb).

    Most fixtures where you would use that type of bulb have a cover over them so a CFL is suitable and already uses almost the same power as an LED.

    This would be a lot better if they made the bulbs for PAR30/PAR20/PAR38 where LEDs are a much better fit, and the only 2 real choices are LED or incandescent/halogen, because CFLs are absolutely blinding in those types of fixtures.
    Reply

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