reg:exp

Prototyping for small screens

I've had an ongoing conversation with several fellow hardware sketchers about good methods for prototyping interactive products with small screens and custom I/O. The hardware input side is taken care of by projects such as Arduino and Wiring; however, finding a suitable screen has been harder. For me, the ideal screen should be: high-resolution with pixel-perfect reproduction of source images, full-screen refresh at >10fps, able to display/mirror an arbitrary region of a desktop PC screen (so you can leverage any and all PC applications), wireless (for both communication and power), available in different form factors from 2"-8".

While the perfect match is still elusive, I've recently come across a useful solution that I wanted to share: DisplayLink screens.

DisplayLink uses USB to add multiple additional displays to a PC or Mac. These show up as regular additional monitors to the OS. Small screens can be USB-powered as well - so while they're not wireless, there's only a single cable. The first screens are just hitting (Japanese) streets now. I recently received a Century LCD-4300U - 4.3" diagonal, 800x480 resolution, bus-powered. These displays aren't cheap ($200) but very convenient. A larger 7" screen with resistive touch input (Mimo UM-740) is on order. Video playback is not a problem, screens a bright and crisp.

Other methods I've personally tried out that fall short(er):

• iPhone / iPod Touch + Mocha VNC Lite: wireless, high resolution, mirrors any part of your desktop; two-finger zoom and pointer input. The major downside: screen refresh has took 2-5 seconds per screen when tested with my home WiFi network and Stanford's campus-wide wireless network. (Hayes Raffle suggested trying this.)


• VGA cable -> scan converter -> composite video signal -> LCD screen.
  Screens with composite video input are relatively easy to find, e.g., through Purdy Electronics. Since input is component video, screen refresh is not an issue. Downside: it's a mess of wires and a lot of resolution and crispness is lost in the scan conversion.

Other approaches from friends:

• Run your application on an Internet tablet: Take the smallest possible device that runs Linux/Flash Player/... and develop/deploy directly on that device
  
  
  
  • IDEO Labs - Hacked Nokia 770 tablet to take Arduino input (Dave Vondle):
  
  
  • Hayes Raffle: Using the Nokia N810 with Flash and Arduino
  
  

• Siftables (David Merrill): Small, wireless (bluetooth); high-level drawing API for realttime updates; Bitmaps need to be cached on-device as drawing pixel-by-pixel takes ~2-3 seconds over Bluetooth.


• IDEO Labs LiveView (Nick Zambetti) iPhone app that duplicates part of your pc screen on the phone. Similar to VNC solution proposed above. Haven't tested it yet to check latency.