Wear-Hard FAQ Version 1.0 8/20/97 1 Introduction This is the second of two FAQs being written about wearable computers at the MIT Media Lab. The first FAQ, Wearable Computers, is primarily focused at general information about wearable computing. It covers non-technical questions regarding interfaces, basic hardware specifications, and user interfaces. The focus of this document is on the resources and knowledge needed to actually build and use a wearable computer. It is almost entirely composed of hardware and software specs, tips, tricks, and hacks that are needed to make wearables happy. 1.1 Wearable Resources Okay... you've looked at wearables and think they're really cool. So cool, in fact, that you want to make your own. But now you're a little confused about where to begin and where to ask questions. Here are the major resources for wearable computers, and a little bit of info about what they can tell you: Wearable Computing FAQs: These are a good first source for information about wearables. If you think you have a common question, just started learning about wearables, or are looking for an overview of what's going on, this would be the place to start. Wearable Computing Webpage: The Intro to Wearable Computing Webpage (http://wearables.www.media.mit.edu/projects/wearables) is probably the next place to look. While the format needs a little bit of help, it will be updatated more frequently than the FAQs, and will cover a very wide range of topics. Wear-Hard list and server: The mailing list wear-hard@haven.org is a resource that performs a variety of purposes. If you have a question that can't be found in the FAQs or webpages, then ask it here. If you want to discuss design ideas, cool softwear hacks, or just find out what's happening in the wearable world, this is the place! To subscribe, please send mail to wear-hard-request@haven.org with the text "subscribe" included in the body of the email. When submitting a question, please give a decent amount of background information regarding the problem. Don't say something like: "My Private Eye won't display an image". Do say: "My Private Eye won't display an image. I'm using the standard Lizzy design, with the PE driver board. The display seems to be getting power - it buzzes - but the screen stays dark. What should I do?!" Wear-hard also acts as a message server. You can request messages stored in it's archives to answer recent questions that have not been added to the FAQ or to the webpage. The list is moving into the moderate traffic range. At some point the list will probably be split into separate aspects of wearable computing to help people deal with this overload. 2 General Wearable design 2.1 Why use the Lizzy design? Why not just hack around a laptop? Laptops tend to be: Too heavy Low battery life Too big Obscure, undocumented hardware - hard to hack difficult to upgrade (Recently) too hot! not robust I have found that people will simply not wear machines that are too awkward. You have to remember my application ... 24 hour intelligent assistance ... thus anything that is not comfortable or doesn't provide good battery life for a day is out. Using the wearable as your primary machine also puts constraints on the minimum amount of horse power ... its a tool, not a toy. The Lizzy design balances these factors. [Thad Starner] 2.2 Are there any companies that build wearables? Yes. Check out the MIT wearables webpage (http://wearables.www.media.mit.edu/projects/wearables/) under "Links to commercial wearables sites." [Brad Rhodes] 3 Displays 3.1 What should I look for in a good display? A general suggestion I'd make to everyone planning displays: the question is not how small you can make the display. The question is what kind of tradeoff you want to make between size/weight, resolution, color, power consumption, and cost. You could make a display the size of a pin for less than a dollar if you didn't mind that it could only display morse code. Given that tradeoff, what do you want to do with your wearable? If it's pure text, you're probably best off with a P4 or P5 (if you can find one). If you want graphics (color or just greyscale) then you'll want one of the LCD screens. If you just want a few bits of information, you can probably get by with the tiny Iota 8-character display. Or you might want to go completely audio. Depends on your application. All the displays we know about are listed at: http://wearables.www.media.mit.edu/projects/wearables/display.html If you know of another one, post it to the list with a URL and we'll add it. [Brad Rhodes] 3.2 What are the MIT media folks using for their eyepieces? The old P4 Private Eye is the workhorse currently. In the process of switching/working on the P5 Faxview modification that PED has just announced as our supplies run out. We also work with our own assemblies and pre-production prototypes - we'll announce these with contact info as they become available for real. Don't believe the hype about a display until you can actually buy one (as in, see if they'll accept your check). Everything we know about (including hype) has pointers on the web site. [Thad Starner] 3.3 Private Eye - Reflection Technology The Private Eye, manufactured by Reflection Technology, is a LED based display that can produce a monochrome image at 720-280 resolution. It uses a vibrating mirror to create this image. 3.3.1 I can't buy a private eye! Why? Reflection technology is in the middle of an upgrade. The model currently used by the Media Lab, the P4, is not being produced. The only way to incorporate one into your system is to buy it used. There are 25,000 of them out there and rumor has it that some have been sold at garage sales for $60. Currently, we are trying to get Reflection technology to sell the next display, the P5. They should be available really soon (as of 8/30/97) The next display is the P7 (yes, it appears that they skipped the P6 designation), scheduled for production in early 1998. This display is 12 bit color, around 640x480 resolution, and should sell for under $100. 3.3.2 I understand the P7 is expected to support color and VGA resolution. How many levels of brightness does Reflection Technologies expect the P7 to support? It is supposed to be a 640x480 VGA LED 4096 colour display. [sten.eriksson@udac.se (Sten Eriksson)] 3.4 The default boom-mount is horrible... what are different ways of mounting the PE? The main mounts are the saftey-goggle mount and the hat mount. Both can be seen on the main web pages: http://wearables.www.media.mit.edu/projects/wearables/Lizzy/pe.html 3.4.1 I tried the eye-glass mounted private eye, and was surprised at how noisy it was. Loud enough that others could hear it! Did you use the Silicon 2 glue? The glue provides some mechanical insulation against vibration/noise. My guess is you have a small air gap where the display is banging against the glasses. The other possibility is that you have a badly put together PE. The vibrating mirror may be glancing off the case. Sometimes this happens with the ones Phoenix did. The Reflection ones tend to be solid - they have a silver tag around the core. As a benchmark, when in a quiet room you should be able to hear the display, but walking around outside you shouldn't (granted I'm in a windy city). As another benchmark, after you wear your glasses for an hour, you shouldn't be able to feel the vibration. [Thad Starner] 3.4.2 Who are all the different companies involved with this? This all started with Reflection Technology making the original Private Eye - what is now the P4. They are not making the P4 now, but are instead focusing on developing the P5 (faxview display) and the P7. They are not going to sell the P5 in single units. However, they have agreed to sell through PED, Inc. PED, Inc. () will act as a reseller for Reflection Technology. Their main goal is to replace the P4 with the faxview. To do this, they will sell modified P5s. At first, they are going to sell the basic faxview display and a basic terminal emulator for it. As more hardware is designed, the P5 will be sold with extra features. Eventually, we hope that this will support an X display... When the P7 comes out, Reflection will sell you several thousand for a very low per-unit cost. They won't sell you individual units, but you might be able to get a developer's kit for around $10k. As soon as the technology takes off, they should become much cheaper and affordable. 3.5 CyberDisplay 3.5.1 Is the "developers kit" really necessary for our uses? Is there any way to get single items otherwise? 3.5.2 What kind of a connector to they have? The Kopin cyberdisplay has a specific interface which requires a bit of effort to hook up to standard VGA (chip and component level hacking). It is 320x240. It also requires a bit of effort to get appropriate optics. [Thad Starner] 3.5.3 How available are they? Are there resellers? There are companies working on integrating all of this in a package to sell. However, they are not available yet. These companies know about this list. When they have something for real, they will post. [Thad Starner] 3.6 Virtual Boy 3.6.1 Could you make a display out of this? Yes. But it's not worth it. The final image would be 384x240 and is a real pain to get working. See the web page for more info. [Josh] 4 Hard Drives 4.1 How are the drives mounted in the cases? I have my hard drive in the case, sandwiched between the case and the 3-board PC-104 stack. To cushion it from the case I've taped in an old foam mouse-pad, and have a bit of duct-tape on top of it to insulate it from the PC-104 boards. Basically held in by friction (it's pretty tight), but I've never had a problem with physical shock. (electrical shorts is a different question). [Brad Rhodes] Mounting the hard drive on the inside held in place by the foam is a good way to keep the shock down. Allowing the components a bit of play (nylon standoffs, foam, etc.) is much better than coupling them firmly to the case. [Thad Starner] 4.2 Would a RAID array be useful for wearables? IDE can only control 2 drives per controller. You'd need to go SCSI. 2.5" SCSI drives are harder to find and more expensive. [Thad] 4.3 How about flashRAM? Flash is hideously expensive. [Thad] 5 Wireless Communication 5.1 I'm looking for advice on medium to longer distance (1+km or cellular) wireless communication devices, with as much bandwidth as I can get... CDPD (links on main Media web page) is probably the best right now for long distance, though 13kbps max. I know Philly has coverage (used it), but I don't know about the Lehigh region. We use the Sierra Wireless PocketPlus modems which use the serial port. Drivers are on the web page under Software. We'll have hardware mods to these things on the web page shortly as well. There are also PCMCIA Type 3 modems that do the same thing. Another trick, if you want to risk FCC ire, is to take a Richochet or Wavelan and unlimit its transmitter. A better trick is to search out the new modems for the unlicensed 5GHz region...I believe there is a RangeLan....if you find anything, please post. Finally, you could always get an amateur radio license!!! [Thad] 6 Motherboards 6.1 Has anyone played with a ZF Micro SBX/386-40? I can't get Linux to load on it, the error is always: hda: irq timeout: status=0x50 { DriveReady Seek-Complete } OK, I solved the problem by putting the line "hda=1572,16,63" into lilo.conf. [Jorge Codina ] 7 Power 7.1 Has anyone thought of using the newer cellular phone batteries? Not that I know of. We have been shifting to Lithium Ion batteries; the type used in newer video cameras. I don't know how long you could run off of a cellular battery. I seem to remember that they only give you around an hour of talk time using the phone... [Josh] 8 Twiddler - Handykey 8.1 How long does it take to get a Twiddler from HandyKey? We are currently shipping (Fedex 2nd Day) 3 - 5 days from receipt of orders. In December - January we were upgrading the Twiddler design and had up to 6 week delays, but we are now current and have Twiddlers in stock. [Chris George, Handykey Corp.] 8.2 The Shift/Caps Lock key seems broken- it's all upcase/numbers The Twiddler has both Caps Lock (0LLLL) and Number Lock (0MMMM). 8.3 I've been using the Twiddler for a while... One of the thumb keys just fell off! This is actually a fairly common occurance for hard Twiddling users. The thumb keys are bound into a single unit by small bits of plastic that eventually fall apart with enough use. There are two main ways to fix this... Getting another plastic key unit from Handykey or gluing the keys in place. Replacing the key unit is more of a temporary fix, as the keys will fall off again. If you take the cover off of the Twiddler, you will see that the plastic thumb keys rest on small pressure-sensitive buttons - miniature keyboard keys. The keys can be glued in place using Crazy Glue or the like. Just use half a drop the bind the key to the top of the button. You don't want to use to much, as it will glue the button into one position!! You can also use some form of Silicon glue instead of Super glue. It gives a much softer feel to the key, and you don't risk gluing the key into a locked position. 8.4 I used the superglue fix, but now the key is stuck! This also happens. The best way to get it off is using nail-polish remover (or, for the well stocked labs, true Acetone) and q-tips. Gently work the button from side to side and keep wiping it down with more acetone. The black color of the button may come off, but the button should still function. 8.5 Have people hacked the Twiddler to draw power directly, or are they still using the keyboard power supply? Here we're still getting twiddler power from the keyboard port. There's a Y-split so you can attach a real keyboard without disconnecting the twiddler. I've heard you shouldn't do that without powering down first, but I've never followed that advice and never had a problem. [Brad] 9 Softwear 9.1 What is a good book to use for learning Linux? The Linux User's Guide from Que is pretty good....what I learned from, even though that was several years ago. Stay away from Linux Secrets - a book with flames on the cover. [Thad Starner] You might want to try "Slackware Linux Unleashed" It's a great book/reference, has Slackware96 and lots of stuff on an extra CD. Put out by Sams Publishing. Downside: It's $49.95 (ISBN: 0-672-31012-0) [Eric eric@allbookedup.com] When I was starting out w/Linux, I found that having hard-copy of docs helped a whole lot, as more often than not, I was bouncing about, recompiling, rebooting, etc, as I was setting things up, and having something to look at aside from the screen was handy. I used a lot of the FAQ/HOWTO files for setting up the specifics of my system... If you're up to purchasing a book, Running Linux looks good as far as system setup and configuration. I myself didn't use it initially, so this is a retrospective opinion...Hence, ymmv. If you've got things all configured and want to get down to learning the nuances of various shell commands and whatnot, get Linux in a Nutshell. I use it often, myself. Essentially, it's like a better version of the Linux man pages, with a few extra tidbits here and there on various topics. Which reminds me of the most impressive resource available online...The Linux Documentation Project. Head to http://sunsite.unc.edu/mdw/ for that. Essentially, it has every piece of info you'll ever need, and then some. I've only had a brief time to even take a peek at what's there, but it looks impressive. [Vandibere Hanson/Jeremy Lemieux (vndibere@oitunix.oit.umass.edu)]