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Tux-Phone

Tux-Phone. Deva Seetharam, France Telecom Research Surj Patel. BACKGROUND. Motivation. Many people think cell phone is the best thing since the sliced bread. Right? It is an excellent hacking and application platform. However, we are not able to exploit its full potential because….

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Tux-Phone

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  1. Tux-Phone Deva Seetharam, France Telecom Research Surj Patel

  2. BACKGROUND

  3. Motivation • Many people think cell phone is the best thing since the sliced bread. Right? • It is an excellent hacking and application platform. However, we are not able to exploit its full potential because….. Cyber Shepherd Of course, Paris Hilton Grameen Phone

  4. Motivation (continued) Cell Phone Vendors

  5. Motivation (continued) • Adding new hardware/software features to commercial cell phones is expensive: $10,000 licensing fee + royalty fee for every RFID reader added to cell phones.

  6. Motivation (continued) • The APIs and architecture are closed. It is difficult to add any new features. For instance, one cell phone vendor requires the following components just to read a NFC tag: Solaris 9, Oracle 9i Enterprise Edition, Bea WebLogic Server 8.1 SP2 Enterprise Edition, Java 2 SDK Standard Edition version 1.4.2 and support for SSH.

  7. PROPOSED SOLUTION

  8. Tux-Phone • An open cell phone platform named tux-phone. • Three important disclaimers: • It is not a novel idea. People have thought and written about similar equipment. • We just started building it. • The engineering process is fairly straightforward except for finding the right parts and putting them together while keeping it small.

  9. Computing Engine LCD Ringer Speaker Mic Keypad Battery System Architecture RF Module

  10. Computing Engine • Options • A custom microcontroller board with custom firmware • A custom microcontroller board with a small OS like Ethernut • An Off-The-Shelf (OTS) board with a custom OS • An OTS with Linux

  11. Computing Engine (continued) We decided to use an OTS board with Linux. • Advantages • Open source • Free • Excellent support for different protocol stacks • Active development community • Extensive support for application development • Disadvantages • Not power-efficient • Not a real-time operating system • Requires plenty of resources

  12. Computing Engine (continued) • We chose Gumstix, a tiny Intel XScale based Linux SBC. • Intel XScale® PXA255 400MHz • Full Linux • Small - 80mm x 20mm x 6.3mm • Wide operating voltage - 3.4 - 5.2V • Two headers for expansion boards • Excellent software support: • Busybox, Boa, uclibc, ssh, • Berkeleydb, Bluez etc.

  13. Embedded Network Enterprise Network Node 1 DB Node 2 Gateway / Reader GSM Module Remote Application Node n RF Module + Antenna • Requirement: A module that can handle all RF communication and provide AT command interface. • Not too many vendors. A few prominent ones are Siemens, Nokia, Falcom and Telit. • These modules were primarily designed for machine-to-machine (M2M) communications.

  14. RF Module + Antenna (continued) • We chose GM862 module from Telit. • Supports 900MHz, 1800MHz and • 1900MHz frequencies • Works with all SIM card • providers currently - AT&T, • T-Mobile, and Cingular. • 17mA average stand-by, • 3.5mA in low-power mode, • 250mA ave. operating current • Support for GPRS, Voice, SMS, • Fax and Camera • Data rate up to 57.6kbps

  15. Display • Gumstix CPU (PXA255) has a built-in LCD controller that can be used to drive LCD modules using the Linux PXAFB driver. • We are using SEIKO Color STN 1.5” (RNH942209R1A) Cell Phone Display.

  16. Gumstix Display (Continued) • Adding LCD support in PXA Linux kernel is fairly straightforward (and well-documented). However, hardware interfacing is tedious due to lack of a proper breakout board. Two options: • Use an adapter board • Create an appropriate breakout board. Breakout-gs Adapter LCD

  17. Audio • A cell phone requires three audio components: • Speaker • Microphone • Ringer • GM-862 supports both hands-free and handset mode. • We have tried only the handset mode.

  18. Speaker • GM-862 requires a speaker with the following characteristics: 16 ohm impedance, signal bandwidth of 150 – 8000 Hz at -3 db and maximum power output of 30 mw.

  19. Speaker (continued) • We are using Panasonic EAS-4D02C0 speaker. This speaker is relatively large (4 cm long) and we are looking for smaller alternatives. • In particular, we are considering Regal Micro speakers.

  20. Speaker (continued) • We are also considering fascinating speaker products from NxtSound, UK. Distributed Mode Behavior Distributed Mode Actuator • Sound waves are generated by initiating and exploiting multiple, organized bending resonances in the panel. Using this technology, LCD protective cover or the keypad can be converted into a speaker.

  21. Microphone • GM-862 manufacturer recommends balanced and buffered microphone. • Biasing circuitry is also necessary to eliminate noise. • We are thinking of using Star Micronics MAA-04B-SA2 Series. • This microphone is attractive because it is small (5.6 x 3 mm), wide operating voltage (1 – 10 v) and -45 db sensitivity.

  22. Microphone (continued) • Another interesting microphone from Star Micronics: 3 mm diameter MAA-03A-L.

  23. Gumstix Ringer • We are just using a piezo audio indicator (CEP-2242) as a ringer for simplicity reasons. • However, a sophisticated ringer can be built using the following design: Low Distortion Audio power amplifier (SSM2211) Audio Codec (UCB1400) Speaker GM-862

  24. Keypad • We are using a Gray Hill 3x4 keypad. • The keypad is connected to Gumstix using the following configuration. 3x4 KEYPAD KEY ENCODER Gumstix R1 R1 R2 R2 D0 – D3 R3 R3 R4 R4 MM74C922 DA C1 C1 C2 C2 C3 C3 C4 • This Keypad is large. It needs to be replaced with a small custom keypad.

  25. Battery • Gumstix takes 3.4 – 5.2 V supply and draws maximum 250 mA current (no bluetooth). • GM-862 module requires 3.4 – 4.2 V and draws a maximum of 1.9 A current. • Other considerations - , battery must be light, safe, rechargeable (several hundred times), easily available and must have a good shelf life. • Considered NiCd, NiMH and Lithium batteries.

  26. Battery (continued) • Nickel Cadmium • Available only in cylindrical shapes. • 3-4 cell pack would be required since a cell supplies only 1.2 v. • Cadmium is a toxic metal and requires special disposal. • Suffers from fast self-discharge. • Nickel Metal Hydride • Available in cylindrical and coin cell form factors. • High current capacity. • 3-4 cell pack would be required since a cell supplies only 1.2 v. • Suffers from fast self-discharge.

  27. Battery (continued) • Lithium Polymer Batteries • Available in 3.7V. • Current capacity – 2000 mAh • Can support continuous discharge at 2C • No special disposal requirements • Rechargeable for several hundred times (not as good as NiMH) • Fast recharge • Slow self discharge • Cool batteries – they were used to power iPods.

  28. Battery 85 GM-862 55 Packaging (Back) Gumstix

  29. 125 Microphone 52 Packaging (Front) LCD Speaker Buzzer Keypad 69

  30. Software Tux Application PXAFB Tux Driver RI LCD Keypad GM-862

  31. Software (continued) • Kernel space code is kept minimal due to the following (obvious) reasons: • Any misbehaving driver can impact the whole system • Kernel API changes much more frequently than the user space API • User space libraries have more features and functionality than kernel space libraries.

  32. Closing Comments

  33. Discussions • Why are you doing this? • To create an open hacking and research platform for us and for everyone. • What is the big deal? • Nothing. As it was described, building a cell-phone is simple, but not necessarily easy. • What is the main challenge? • Stitching together multiple components while keeping the size down is the main challenge.

  34. Discussions (continued) • How much would it cost? Approximately, $400.00.

  35. Discussions (continued) • Does it make sense? • Hope so. We have met several researchers/hackers/small businesses that could use an open cell phone platform like this one. • Why not use a Linux PDA? • Hardware schematics are usually not available. Modifying those PDA-based cell phones can be difficult. • What next? • Create a cell phone breakout board • Find a small antenna • Find a small keypad • Complete drivers • Complete applications

  36. Discussions (continued) • Is the project sustainable? • Not sure. Unlike software open source projects, as you can imagine, hardware projects are expensive. Unlike there is funding, it may not be possible to continue the project.

  37. Thank You! Gracias! Merci!

  38. Acknowledgements • Colin Cross – a master hacker and a friend • Gumstix community • GM-862 community

  39. Resources • Round Solutions – http://www.roundsolutions.com • Gumstix – http://www.gumstix.com • SparkFun – http://www.sparkfun.com • DigiKey – http://www.digikey.com • Mouser – http://www.mouser.com • Linux HOWTO – http://www.tldp.org • Linux Device Drivers - http://lwn.net/Kernel/LDD3/ • Linux Kernel – http://www.kernel.org • Blog – http://www.surjpatel.com

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