Communication systems engineering
Communication systems engineering
Perpetual environmentally powered sensor networks
IPSN '05 Proceedings of the 4th international symposium on Information processing in sensor networks
A building block approach to sensornet systems
Proceedings of the 6th ACM conference on Embedded network sensor systems
On the limits of effective hybrid micro-energy harvesting on mobile CRFID sensors
Proceedings of the 8th international conference on Mobile systems, applications, and services
A case for custom silicon in enabling low-cost information technology for developing regions
Proceedings of the First ACM Symposium on Computing for Development
Sustainable sensing for a smarter planet
XRDS: Crossroads, The ACM Magazine for Students - Green Technologies: From Pollution to Pixels
MELOS: a low-cost and low-energy generic sensing attachment for mobile phones
NSDR '11 Proceedings of the 5th ACM workshop on Networked systems for developing regions
Ekho: bridging the gap between simulation and reality in tiny energy-harvesting sensors
HotPower '11 Proceedings of the 4th Workshop on Power-Aware Computing and Systems
AudioDAQ: turning the mobile phone's headset port into a universal data acquisition interface
Proceedings of the 11th international conference on Information Processing in Sensor Networks
MusicalHeart: a hearty way of listening to music
Proceedings of the 10th ACM Conference on Embedded Network Sensor Systems
Energy efficient GPS sensing with cloud offloading
Proceedings of the 10th ACM Conference on Embedded Network Sensor Systems
Proceedings of the 10th ACM Conference on Embedded Network Sensor Systems
The CLEO mobile sensing platform
Proceedings of the 10th ACM Conference on Embedded Network Sensor Systems
Septimu2 - earphones for continuous and non-intrusive physiological and environmental monitoring
Proceedings of the 10th ACM Conference on Embedded Network Sensor Systems
Open data kit 2.0: expanding and refining information services for developing regions
Proceedings of the 14th Workshop on Mobile Computing Systems and Applications
EnGarde: protecting the mobile phone from malicious NFC interactions
Proceeding of the 11th annual international conference on Mobile systems, applications, and services
Retrofitting smartphones to be used as particulate matter dosimeters
Proceedings of the 2013 International Symposium on Wearable Computers
The mote is dead: long live the discarded smartphone!
Proceedings of the 15th Workshop on Mobile Computing Systems and Applications
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We endow the mobile phone with a low-cost, open interface that can parasitically power external peripherals, and transfer data to and from them, using analog, digital, and serial signaling, using only the existing headset audio port. This interface, called HiJack, allows the mobile phone to easily integrate with a range of external sensors, opening the door to new phone-centric sensing applications. In this paper, we characterize the signaling and power delivery capability of the audio jack, design circuits and software to transfer data and harvest energy, and evaluate the performance of our designs. We also use the mobile phone's audio channel to create a layered communications stack that supports low-level, analog signaling and high-level, multiplexed data communications with external devices. Our design supports a single, bi-directional communications channel at a data rate of 8.82 kbps over a Manchester-encoded serial stream, using just a few discrete components and the hardware peripherals found in almost any microcontroller. Our harvester delivers 7.4 mW to a load with 47% efficiency using components that cost $2.34 in 10K volume. Integrating the pieces, we present a combined system for delivering data and power over audio, and demonstrate its use by turning an iPhone into an inexpensive oscilloscope.