dseetharam etel 2006

Tux-Phone: 

Tux-Phone Deva Seetharam, France Telecom Research Surj Patel

Slide2: 

BACKGROUND

Motivation: 

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….. Grameen Phone Of course, Paris Hilton Cyber Shepherd

Motivation (continued): 

Motivation (continued) Cell Phone Vendors

Motivation (continued) : 

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.

Motivation (continued) : 

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.

Slide7: 

PROPOSED SOLUTION

Tux-Phone: 

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.

System Architecture: 

System Architecture

Computing Engine: 

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

Computing Engine (continued): 

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

Computing Engine (continued): 

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.

RF Module + Antenna: 

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.

RF Module + Antenna (continued): 

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

Display: 

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.

Display (Continued): 

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

Audio: 

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.

Speaker: 

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.

Speaker (continued): 

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.

Speaker (continued): 

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.

Microphone: 

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.

Microphone (continued): 

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

Ringer: 

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: Speaker

Keypad: 

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

Battery: 

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.

Battery (continued): 

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.

Battery (continued): 

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.

Packaging (Back): 

Packaging (Back) Gumstix

Packaging (Front): 

Packaging (Front) LCD Speaker Keypad 69 Buzzer

Software: 

Software RI

Software (continued): 

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.

Slide32: 

Closing Comments

Discussions: 

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.

Discussions (continued): 

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

Discussions (continued): 

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

Discussions (continued): 

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.

Slide37: 

Thank You! Gracias! Merci!

Acknowledgements : 

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

Resources: 

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