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

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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

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How about its performance?

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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

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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

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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

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What can you do with an NFC-WISP?

Lots…

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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)

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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?

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No

Application – Data logger with

Display for Cold Chain Monitoring

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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

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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

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Application – Wireless Charging

Tx Power:1 Watt

Combine NFC RFID with wireless power

– A4WP (Rezence) (13.56MHz)

– Magnetic coupled resonance

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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

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Future Work

• Dynamically optimize power harvesting efficiency

• Sensing enhanced cell-phone with NFC-WISP

• Implement more NFC protocols

• Explore more NFC application

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Thank you & questions?

31

Backup slides start

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… and more33

Challenge 3: Power Management

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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