1 / 20

Introduction

Equinox : Subverting the Dominant Paradigm in Consumer Electronic Design John Miles . Introduction. - Who am I? - “Beware of programmers with screwdrivers.”

ayala
Download Presentation

Introduction

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Equinox: Subverting the Dominant Paradigm in Consumer Electronic DesignJohn Miles

  2. Introduction - Who am I? - “Beware of programmers with screwdrivers.” - I have a history of solving hardware problems with brute force…

  3. … and a pronounced tool fetish

  4. Evolution of Equinox

  5. Meet the ICF-CD873 …

  6. Meet the ICF-CD873 … • 20 buttons on top surface • Only “Snooze” is easily recognizable by touch • Impossible to set clock or alarm by feel • Blinding LCD backlight • Annoying “Voice Plus” feature • Never miss a 3:00 AM power glitch again!

  7. So, how do we fix it? • The ICF-CD873 is a good target for mockery, because it’s a perfect example of the “one size fits all” fallacy • Your desired features != mine • Maybe you want a radio with 20 buttons you can’t see • OK, enough about the buttons already, we get the idea • Let’s define my feature list…

  8. Wish List: Radio Performance • True “DC to daylight” radio coverage • Nowadays, this means at least DC-1 GHz • Imagine a 25-foot long radio dial… • All common modulation types • AM for standard AM broadcast, aircraft • WBFM for standard FM broadcast, TV audio • NBFM for weather, Amateur Radio repeaters, public-service bands • SSB/CW for HF Amateur reception • Oh, yeah… trunk-tracking scanners are hella cool. I want one of those, too. • Don’t care about CDs…

  9. Wish List: Clock Display • Large clock display with automatic dimmer • I couldn’t read the Sony’s display from 3’ away without glasses • Original plan was to use 1” LEDs • These gave way to Burroughs B7971 Nixies • Eventual solution: 7” LCD touchscreen with rendered B7971s • Even better solution: LASIK surgery :-P

  10. Wish List: Features/Ergonomics • It wouldn’t have taken much for me to be OK with the Sony’s feature set • Front-mounted controls (or at least haptically-correct ones) • Automatic time setting • Battery backup • No howlingly-stupid features (“Voice Plus”) • Ability to access receiver from anywhere

  11. The All-Important GAF (Girlfriend Approval Factor) • Receiver outgrew two smaller enclosures • 4U rack-mount server chassis = bad news in the bedroom, in more ways than one • Antenna connections, cabling also awkward • Ended up with dedicated client PC (Mini-ITX) in receiver’s first enclosure choice • GAF/WAF isn’t just snarky sexism in action, but a valid expression of a legitimate design goal. A design that considers the needs and tastes of “normal people” will LAST.

  12. Technical Highlights • Main Receiver • Quad-conversion superheterodyne • DC-1 GHz, all-mode coverage • Auxiliary Data Receiver (ADR) • Single-conversion, single-frequency superheterodyne • Continuously monitors King County trunked-radio system control channel at 868.175 MHz

  13. Technical Highlights • Each receiver has its own Atmel ATMega128 microcontroller • 8-bit 16 MHz CPU with 128K program memory, 4K RAM • Lots of parallel and serial I/O ports, timers, ADCs… • Supported by free AVR-GCC C++ compiler • Atmel C++ code cross-compiles under MSVC for module-level testing on bench via parallel ports • Board in photo is AVR-H128 from www.sparkfun.com; many other vendors offer similar development boards

  14. Technical Highlights • Main and auxiliary receiver controllers interfaced to Via EPIA Mini-ITX motherboard in server chassis via RS-232 • Trunking data (talkgroup updates, etc.) • Commands from server to receiver hardware on behalf of clients • Status/signal reports from receiver to server for distribution to clients • This is all low-bandwidth traffic (38.4 kbps, plain ASCII text for easy diagnostics) • Audio output from main receiver demodulator assembly sent to onboard audio line-in jack for digitization and streaming • Audio transmitted as 11 kHz mono • Local clients get 16-bit PCM • Remote clients get ADPCM

  15. Construction Example: Main Antenna Input Assembly • Receiver is built as array of interconnected modules • Better for RF signal integrity • Easy to change your mind! • Modules can be reused as-is in future revisions of the project, or in different projects altogether • Expensive parts like filters and coax relays scavenged from (formerly) high-end telecom / test equipment…

  16. Construction Example: PLL Synthesized Local Oscillator • Offers tuning resolution and coverage normally found in military / government receivers • This is the only professional-quality PC board in the receiver • More R&D time (months) than any other assembly

  17. Construction Example: Second Converter Assembly • Good example of “dead bug” home construction technique • Even hardcore RF tinkerers don’t realize this technique is usable beyond 1 GHz! • Among the best ways to work with RF at the prototype level, but… • Testing is important, since you can’t always model or predict exact circuit behavior • This is where your equipment fetish can really save the day!

  18. More Dead-Bug Action… • Short leads on components, direct connections to ground plane make your circuit ugly • That means ugly = good! • Electrons have surprisingly-little regard for aesthetics…

  19. Design Resources • Equinox receiver project page www.ke5fx.com/equinox/equinox.html • Download the client app and give it a spin! • John Miles, KE5FX, and Richard Hosking, VK6BRO, “A Versatile Hybrid Synthesizer,” QEX, Mar-Apr 2004 • Also available online at www.ke5fx.com/synth.html • Analog Devices ADIsimPLL design tool (www.analog.com) • AVR-GCC multiplatform C++ compiler (www.avrfreaks.net/AVRGCC/) • QEX/Communications Quarterly (www.arrl.org/qex)

  20. Component Sources • www.ebay.com • Business & Industrial • Industrial Electrical & Test • Electronic Components • Test Equipment • Alphatronics • In Tukwila, not far from Fry’s and other attractions • http://shop.vetcosurplus.com/catalog/ • In Bellevue, great selection of RF coax/connector hardware, much more • www.digikey.com • Largest selection / best service / moderate prices • www.minicircuits.com • Personal financial Armageddon for the RF hacker • www.jameco.com • Similar to Digi-Key • www.futurlec.com • www.sparkfun.com • Good sources for microcontroller prototyping aids, other parts

More Related