A Programmable Accessory for. Rohit Chaudhri Computer Science and Engineering University of Washington

Transcription

1 A Programmable Accessory for Cell Phones Rohit Chaudhri Computer Science and Engineering University of Washington

2 Phone Logger -Initial MSRI Usage logger for low-tier phones Understand typical phone usage Voice calls, SMS, games/apps, missed call messaging Correlate usage with socio-economic status/mobility Infer human dynamics/behaviors (reality mining) Low cost, minimal intrusion Go beyond in-person interviews and phone logs Get a better understanding of how a poor person uses (mobile) technology - Toyama

3 Phone Logger -Requirements Usability logging Key presses UI navigation Apps used on the phone Communication usage Phone calls: inbound, outgoing, duration SMS: send, receive

4 Phone investigation Daemon software on mid-tier phones WinMo, Symbian, J2ME Expensive Changes the user experience Common low-tier phones NOT programmable Nokia S30, S40 (1100,1200/3, 1650,3300 etc.) Can we build an external, pluggable logger? Monitor usage via a connected device

5 External Interfaces GSM specified AT commands over data port Send/recv SMS, phone calls, monitor key press Implementation varies across vendors/models Not implemented on low-tier phones FBUS protocol Implemented on low-tier phones FBUS pin-outs available on pop port Can monitor communication usage Monitoring usability not possible

6 High Level Architecture Serial link to MCU Battery powered Memory card DTMF decoder Input to accessory Pop Port Audio out Serial Audioin MCU Storage DTMF Decoder Battery To headset Serial MCU Battery Storage Pop Port

7 Generic Capabilities Leverage phone for IO Display strings on phone display Possible on very few phones DTMF decoder for input from phone Also enables audio prompts as output Communications Initiate/receive voice calls and SMS Cell tower-id based location sensing Additional sensing via IO ports

8 Hardware 0.0 Dev board 2.0 Current version NXP s ARM7 board 60Mhz, 40KB RAM, 512 KB Flash, Several IO interfaces Memory card for additional storage ~$15 in prototype scale lower with cheaper processor (e.g. 8 bit Atmel -$2) Tested with Nokia 1200/3/8/9, 1650/61/62, 2660, 6020 Ref for supported phones (FBUS,AT,USB)

9 Logging Application Configure phone on start-up Phone notifies accessory Voice call initiated, received, hung up, rejected SMS sent, received Query cell tower-id for location Events logged to SD card Event log parser desktop User study MSRI support staff

10 Location Tracking MSRI-SP Road 10 mile round trip Accessory connected to Nokia 1200 Scan cell tower-id every 2 minutes Data stored on memory card, processed offline 1 Paisa (0.02 Cents!) to upload via SMS Unofficial Google API to map cell-ids to geo coordinates

11 Remote Sensing In the works Connect motion, temperature, voltage sensors Readings periodically sent via SMS Query/configure sensor remotely via SMS

12 Possible Deployments Refrigerator temperature/voltage sensing PATH Location tracking LabourNet, Operation ASHA (India) Energy plant monitoring Data to help distribution/maintenance.

13 Future Directions Deployments Sensing applications Biometrics, Telemedicine, Healthcare Biosensors hosted on device for on-the-field diagnostics Phone used for communication and control asset tracking (barcode reader) Integrate with cell phone Draw power from phone s battery Connect to smart phones to enhance sensing capabilities A better name than accessory, box, device!

14 Discussion Mobile apps in the developed world often target smart phones Location-aware, BT/WiFi-aware, movement-aware... Low-tier phones lack capabilities to support such apps Voice/SMS devices, lack hardware & software APIs Can low-tier phones be extended cost-effectively to enhance capabilities? Smart sensing, networked computing Sacrifice on user-experience (or perhaps customize to suit user?)

15 Scratch pad Price point - $15 (all developed in India) Where is this adding value? (ref G s discussion for nsdr paper) Low cost networked, programmable sensing platform. Enabling computing cost effectively in environments with minimal infrastructure money, network, lack of PC, unreliable power supply. But still need autonomous computing. Why wldthis be a good idea? Penetration of low tier phones in LIGs Updates to pow-wow SP road location trace Evolutions: rev 2 Operation modes disconnected(battery powered), running fm phones battery-integrated into phone s battery door. Deployment possibilities Perhaps end with a longer term vision for what this could evolve into.

16 Discussion Low-cost, networked, general purpose computing/sensing platform Smartphone minus the user experience? Applications/deployments will evolve the Applications/deployments will evolve the platform