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NFC-WISP: A Sensing and
Computationally Enhanced Near-Field
RFID Platform
Disney Research, Pittsburgh†
University of Washington‡
Yi (Eve) Zhao†‡, Joshua R. Smith‡, and Alanson P. Sample†
Traditional NFC Applications
Secure Payment Access Control
Information Retrieval Item Tracking2
Tap to exchange
ID
What else we can do with NFC?
3
It’s not only about the ID anymore…
Pushing beyond “tap to activate”
User Interfaces(Antenna modification)
N. Marquardt, etc, “Rethinking RFID: Awareness and control for interaction with RFID systems”, SIGCHI ’2010. 4
Battery-freehuman-to-computer interaction device
Pushing beyond “tap to activate”
Implantable Sensing-Glucose monitoring
(Fully custom ASIC)
A. Dehennis, etc, “A Near-Field-Communication (NFC) Enabled Wireless Fluorimeter for Fully Implantable Biosensing Applications,” IEEE International Solid-State Circuits Conference, 2013
5
Sense without wires and battery
Expensive long IC design cycles
Unique Features of NFC
6
Implanted SensorsUser Interfaces
• Wireless power transfer
• Ultra-low power communication
• Simple architecture & cheap
Motivation
• ChallengesFor research & fast prototyping
– High barrier to entry
– Expensive custom IC design cycles
7
Researchers
IC Design
• Opportunity
– Ubiquitous handheld readers
– Pervasive NFC tags
Motivation
8
Tools to explore next generation of
Near-Field RFID
before IC design
Sensors & Interface
Research area
…
NFC-WISP
• Fully programmable
(protocol & application)
• Passive(without battery) / Semi-passive(battery assistant) / Active(battery powered)
• Wireless charging
• Design for easy integration of peripherals and testing
• Build-in Sensors & User interface
• ISO-14443 Type-B protocol
Near-Field Communication - Wireless Identification and Sensing Platform
9
• MSP430
Hardware Overview
10
Topview
• User interface:Buttons & LEDsE-ink display
Bottom view
• Energy Storage:Ceramic cap
Battery / Super cap
• Header:ADC , SPI, UART, I2 C
2.5V SupplyReal time clockRectified DC voltagesTest points
• Sensor & Memory 3D Accelerometer
2MB FRAM
Thin-Film Li-lonbattery
System Architecture
11
ISO 14443 Type B ISO 14443 Type AISO 15393
Rectified voltage monitor & Li-ion battery management
Q ≈ 20 Optional
Challenge 1: Clock and Data Recovery
• Signal amplitude and Bit-width vary with distance and load
• 10% AM modulation
Mic
roco
ntr
olle
r(M
SP
43
0)
Low Pass Filter
Low Power Wake Up
High Speed Threshold
Baseband Downlink
Baseband Uplink
Data Wakeup
Modulator Envelope Detection
RF
Inp
ut
13.56MHz Crystal
Bit Line
Bit Line Reference
Challenge 1: Clock and Data Recovery
• Signal amplitude and Bit-width vary with distance and load
• 10% AM modulation depth
Envelope of received signal
Bit-line
Bit-lineReference
Data “b000..”
Data “b11”
13
Challenge 2: RF bandwidth
Power harvesting efficiency
v.s.
Communication bandwidth(ISO 14443 Type B require 847.5kHz)
Q=f0f2-f1
14
Challenge 3: Power Management
15
MSP430 start up
RectifiedVoltage (V)
4.2
2.7
1.8
5.6
Item Operation Voltage
Li-ion battery 2.7~4.2 V
E-ink 2.3~3.6 V
MSP430 1.8~3.6 V
Others 2.0~6 V
MSP430 powered off
Max Voltage
Disconnect battery
Connect battery
Regulated voltage2.5V
Challenge 4: Firmware
• Low power• Software defined NFC
protocol• Easily extendable
16
How about its performance?
17
Performance: Reading Distance
Category Mode Reader TypeTx Power
(mW)Distance
(cm)
ReadDistance
PassiveTI TRF7970AEVM 200 3
Nexus 5 <200 0.5
Semi-Passive/Active
TI TRF7970AEVM 200 11.5
Nexus 5 <200 1.2
Limited by
• Up-link (tag to reader)
• Protocol18
Performance: Energy Harvesting
• Limited by – Antenna design (Q)– Bandwidth of analog front end – Max Battery charging current
Category Mode Reader TypeChargingCurrent
(mA)
Charge hours for 10mAh battery
(20% loss)
Extra harvested
current
Sleep modeTI TRF7970AEVM 4 3
Nexus 5 1.9 6.3
NFC Reading mode
TI TRF7970AEVM 3.7 3.2
Nexus 5 1.6 7.2
19
Category Current/Power Duration
Sleep Mode(disable FRAM)
9.7uA
Sleep Mode(Enable FRAM)
12.7uA
Demodulation(REQB command)
2.6uJ 783uS
Modulation(ATQB command)
11.4uJ 1.6ms
Single read of Accelerometer 267nJ 45us
Single read of Temperature sensor (ADC)
369nJ 94us
Temperature sensing andE-ink updates 1 line
3.6mJ 0.57s
E-ink Update 1 frame 8.4mJ 0.57s
E-ink Update 4 frames 9.72mJ 0.98s
Performance: Energy Consumption
Estimate powerconsumptionfor yourapplications
20
NFC-WISP vs.
UHF WISP
Feature NFC-WISP UHF WISPPhysical layer Near-field (13.56MHz) Far-field (915MHz)
Harvestable Power ~10mW ~0.010mW
Reading Range 0.03m 8.0m
Mode Passive or Semi-passive Passive
Protocol ISO 14443 Type B EPC Gen 2 (18000-6c)
MCU MSP430F5310 MSPFR5969
Memory 2MB external FRAM + 32KB FLASH + 2k RAM
64K FRAM + 2K SRAM
Feature Ultra low power sensing & display
Ultra low power sensing
21
What can you do with an NFC-WISP?
Lots…
22
Application – Display tag
• Secondary screen for smart phone
NFC-WISP with 2.7” E-ink display • Energy Neutral• Dense energy storage needed
(battery or super cap)
23
NFC-WISP with 2.0” E-ink display • Also Energy Neutral• >300uF
(Without battery or super cap)
Protected logo
Protected logo
Protected logo
Does NFC-WISP only work when
tapping onto the reader?
24
No
Application – Data logger with
Display for Cold Chain Monitoring
25
Vaccine Food/Drink
…
Transportation
Application – Data logger with
Display
Cold Chain Monitoring Simulation
• NFC-WISP in Active Mode(with battery)
• Sensing– Temperature
– Orientation
– Movement state
• Real time display state on E-ink (without reader)
• Read historical sensing data with NFC reader
26
Motion
A B C D E F G
A: Moving milk box
B: Carry and put it into fridge
D: Heat box up
E,F: Change orientation
G: Read data with NFC reader
Temperature & motion logging
27
Application – Wireless Charging
Tx Power:1 Watt
Combine NFC RFID with wireless power
– A4WP (Rezence) (13.56MHz)
– Magnetic coupled resonance
28
Tx Power:1 Watt
NFC-WISP is Open Source!!
• http://nfc-wisp.wikispaces.com/
Wiki & Forums Source Code(BSD license)
Hardware CAD files(Schematics, layout & Gerbers)
…as of today
29
Future Work
• Dynamically optimize power harvesting efficiency
• Sensing enhanced cell-phone with NFC-WISP
• Implement more NFC protocols
• Explore more NFC application
30
Thank you & questions?
31
Backup slides start
32
… and more33
Challenge 3: Power Management
34
5.6
C) Falling Edge: Disconnect Battery (Passive Operation Only)
B) Rising Edge: Supervisor Enable (regular & battery controller)
A) Over-Voltage Protection @ 5.6V
D) Falling Edge: Warning (min voltage for E-ink)
E) Falling Edge: Supervisor Disable (system power down)
4.2
2.72.3
1.8
Rec
tifi
ed V
olt
age
(V)
Time
Linear Regulator
(2.5V)
Optional (Thin Film Battery
or Super Capacitor)
Charge Controller
SupervisorLow Voltage
Warning(2.3V)
NFC-WISPDigital Core
Voltage Measurement
Circuit
Full Wave Rectifier(3 Stage)
VRegulated
VRectified
SupervisorRising – 4.2VFalling – 1.8V
Enable
VRectified
RF
Inp
ut
35