Missing: OLPC XO BTest-4 Keyboard LED Lights


Reading theCommunity News, I noticed that Bernardo Innocenti and Walter Bender are finalizing OLPC keyboard layouts for XO laptop mass production by Quanta Computer.

olpc keyboard light
B4(l) & B2(r) keyboards up close

And that reminded me of a big difference between the BTest-2 and BTest-4 "$100 laptops" I noticed when I reviewed both at the Washington Post.

If you look closely at the plastic bank just above the keyboard, you'll see what I saw was missing: the BTest-4 doesn't have keyboard lights.

Instead, the OLPC designers have moved the LED's to thinned out plastic areas on the front bezel for "glowing" camera and microphone "in-use" indicators - a security measure so neither can be turned on without the user knowing. And while I think that's an interesting, if a little paranoid, security measure, I do miss the idea of lights shining on the XO keyboard in a dark village home.

How many times have you been typing in the dark, so blinded by the screen light that you have to tilt the display down to illuminate your keyboard? And if the OLPC screen is in a low-watt mode, the keyboard will be even harder to read - a seemingly common and perfect use case for LED's shining on the keyboard.

Last but not least, wasn't the Children's Machine touted as the "brightest light source in the house"? The loss of the keyboard lights dims its chances of replacing the 60 Watt bulb as the illumination of choice in the developing world.

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"And while I think that's an interesting, if a little paranoid, security measure, I do miss the idea of lights shining on the XO keyboard in a dark village home."

Millions of XOs distributed to children. Someone cracks the security (government, rebels, foreign government, pedophiles, neighbors) and can "read" audio and video from a distance. Think about the consequences.

This ACTUALLY HAPPENS with MS Windows boxes.

Hacked machines are used to spy on their owners for fun&profit.

I think the biggest perceived threat would be the local government. By hard-wiring the light, this simply cannot happen without opening the machine. No ifs or buts.


Wayan says: "Last but not least, wasn't the Children's Machine touted as the "brightest light source in the house"?"

I can't remember anyone saying that with regards to the X0... To the best of my knowledge the only time that topic of illuminating the house came up was during the "60 minutes" segment when Negroponte was talking about how laptops that they had sent to that community in Cambodia were being used.

Plus for a light source it would be much more efficient to simply connect some LEDs to the USB's 5V source and put them on some flexible arm or something.


You and I both know that even a basic flashlight would be a more appropriate light source than a laptop computer screen to illuminate a house at night, but if you listen to Negroponte's many speeches, you'd get a whole other impression.

That laptops, and by association, the XO, are great illuminators in the physical as well as educational sense. Hence my sarcastic pun.

My bad, I absolutely didn't get that pun... :-|

The one thing I like the most about my ThinkPad is its LED light, that allows me to write in the dark, without worries about key location. And at least in the Andean schools here in Peru, a cloudy day can be quite dark, especially since many classrooms tend to be built without large windows and do not have electric lighting. So, yes, it would have been very nice to have some "illumination".


Funny enough, that very ThinkPad LED light that I too have on my new work laptop is what made me think of the keyboard lights (or lack there of) on the OLPC XO computer.

I only wish that the computer could sense the ambient light and automatically have the LED turn on. Do you know if that's possible on a T60?

Ambient light sensing can be done very cheaply by silicon phototransistors or cadmium sulfide photoresistors, but these have to be built in. The camera on the XO could, in theory, be used if it were provided with a diffuser to capture total ambient light, not just the light of the scene within its field of view. You wouldn't be able to use the diffuser and still take a picture - the two modes are mutually exclusive.

It would probably be better to rely upon the user's judgment to decide when to turn on the power-hungry illuminating LEDs. That's more a human interface problem.

Wayan, I just have a relatively modest T40, no hacks allowed since it's University property. As Lee says, power consumption could be a problem with XOs, and since (at least from the Peruvian experiment info I read) batteries are not as good as intended yet, they have probably decided to take it out to increase performance. Hopefully, it will return in a coming release. It would be great.

Eduardo Villanueva Mansilla,

"they have probably decided to take it out to increase performance"

From BTest-4 Release Notes
( http://wiki.laptop.org/go/BTest-4_Release_Notes ):

"Removed feature:

* The keyboard lights did not work well and added cost. We removed them. We have ideas on how to uniformly illuminate the keyboard cheaply in future generations but these ideas were too late for this generation of the OLPC system."

The keyboard lights that we first implemented cost well over $1. This is because they required cables, connectors, and a little circuit board on which the led was soldered. It adds up.

I figured out a way to put the LED keyboard light on the motherboard I first lightpiped up from the motherboard, and then used a prismatic sheet to refract the light to the keyboard for about $0.15 per keyboard light. However, just tilting the display forward achieved the basic ability to make out the keyboard keys while typing in the dark. The $0.15 keyboard light was better, but given the smaller size of the laptop, and thus the closer distance of the screen to the keyboard, the performance was adequate for a kid (also shorter and requiring less tilt) and thus we could omit the $0.30 on the bill of materials

It's quite simple to add an LED via USB port as a flashlight. There are many opportunities for peripherals for the XO laptop.

- Mary Lou Jepsen, Chief Technology Officer, OLPC

ps: thanks for the great work you continue to do at olpcnews

Mary Lou,

Thanks for the backstory on the keyboard lights. When I first saw them, I thought they were an innovative aspect of the OLPC design, and even though you say they're not needed on the XO-1, I still miss them if only for the design hint for other laptop manufacturers.

I have to agree with Lou Jepsen - this is a non-essential feature many laptops don't even have.

Leds as indicators of camera or mic use are essential to protect the privacy of kids who could be tricked into running a game that they did not know was spying on them.

Seems I am not the only one who misses the keyboard lights - so does Reynaldo H. Verdejo, their kernel driver writer:

"I'm not good with dates but I will go ahead and pretend the code made a few hundred keyboards shine for about two months, now its gone. It turned out the LEDs where not fulfilling their purpose not to mention they sucked too much power so they were banned.

These LEDs were for me like a badge for others; a way to open some doors. From there I have done a few things but sadly -- none of them 'shines' the way these folks did. I'm going to miss them, Can't help it."

Last weekend I gathered some resistors and LEDs which I had heavily used during my case-modding days. We might build a simple USB-powered keyboard light at a festival in the south of Austria later this week. Additionally we're thinking of writing a simple activity that allows you to control the light (turn on/off) via a software interface.

Of course that solution is going to be more complicated and expensive than what Mary Lou is working on but it could still be a nice add-on for some children.