Course Project Project team forming deadline has passed Project teams will be announced soon Next step: project proposal presentation Presentation slides and one-page proposal document are due on Jan 30 Important: include a project plan with itemized goals in your proposal Especially the ones for the first milestone You will have the chance to revise further objectives at each interim milestone First milestone: Feb 13 and Feb 20 ECE 1161/2161 Embedded Computer System Design 2 1
ECE 1161/2161 Embedded Computer System Design 2 Embedded Communication - I Wei Gao Spring 2018 2
Communication Technologies Tradeoff between data rate and communication range Data rate Communication range ECE 1161/2161 Embedded Computer System Design 2 3
Communication Technologies Considering energy consumption Energy consumption Communication range ECE 1161/2161 Embedded Computer System Design 2 4
Radio-Frequency Identification (RFID) Small tags Wirelessly send data when being triggered by a reader ECE 1161/2161 Embedded Computer System Design 2 5
Radio-Frequency Identification (RFID) Types of tags Passive Operational power scavenged from reader radiated power Semi-passive Operational power provided by battery Active Operational power provided by battery Transmitter built into tag ECE 1161/2161 Embedded Computer System Design 2 6
RFID Market Auto Immobilizers Automated Vehicle Id Access Control Animal Tracking ECE 1161/2161 Embedded Computer System Design 2 7
RFID Market Dock Door Conveyor Belt Forklift Printers Handheld Smart Shelves Point of Sale ECE 1161/2161 Embedded Computer System Design 2 8
Radio-Frequency Identification (RFID) Tag details ECE 1161/2161 Embedded Computer System Design 2 9
Communication Modes Near-field: inductive coupling LF and HF frequency bands Reader generates magnetic field Mini transformer Tag is powered by inducted current Tag is modulated to communicate Inductive Coupling N Reader S TAG ECE 1161/2161 Embedded Computer System Design 2 10
Communication Modes Far-field: backscatter UHF and microwave bands Backscatter Tag is powered by resonance Tag modulates backscatter by changing antenna impedance Reader TAG ECE 1161/2161 Embedded Computer System Design 2 11
Generic Tag Architecture Diode for directional transmission Write Path Receiver Antenna D S G Transistor for transmission control Memory Protocol Engine ECE 1161/2161 Embedded Computer System Design 2 12
RFID Protocols ECE 1161/2161 Embedded Computer System Design 2 13
Class 0 Protocol Operating frequency: 3.3 MHz for data 1, 2.2 MHz for data 0 FSK modulation ECE 1161/2161 Embedded Computer System Design 2 14
Class 0 Protocol Typical data stored in tag Globally unique identifier 96 bit EPC code 24 bit kill code 16 bit Cyclic Redundancy Check (CRC) ECE 1161/2161 Embedded Computer System Design 2 15
Class 0 Protocol Electronic Product Code (EPC) data standard ECE 1161/2161 Embedded Computer System Design 2 16
Class 0 Protocol Signaling ECE 1161/2161 Embedded Computer System Design 2 17
RFID Readers Implementation challenges Must deliver enough power from RF field to power the tag Must discriminate backscatter modulation in presence of carrier at same frequency 70db magnitude difference between transmitted and received signals Interference between readers Hugh volume of tag data readers need to filter data before releasing to enterprise network ECE 1161/2161 Embedded Computer System Design 2 18
RFID Reader Hardware Design Micro- Controller Crystal DAC Power Control Host Device Baseband & Protocol PLL VCO Coupler PA Coupler FPGA DAC RFID READER RF Module Regulation ADC AGC Filters I/Q Demod Filter Coupler Power Detect Transmit path Receive Path Frequency Synthesizer Digital ECE 1161/2161 Embedded Computer System Design 2 19
RFID Reader Software Stack Network Interface Network management Custom Custom Application/ Protocol Protocol Reader Protocol Application RFID Reader API Library Platform API Libraries O/S High-Level Interfaces Low-Level Interfaces File Systems Network Protocols Hardware ECE 1161/2161 Embedded Computer System Design 2 20
What s the Future Backscatter out of the reader Using other wireless signals on the air as the helper to backscatter Any wireless device can potentially become a RFID reader! Need redesign on both the wireless device and RFID tag ECE 1161/2161 Embedded Computer System Design 2 21
WiFi Backscatter WiFi signal as carrier wave WiFi signal as carrier wave Signal Reflection ECE 1161/2161 Embedded Computer System Design 2 22
WiFi Backscatter Key challenges At the tag: how to re-modulate the incoming signal? Data is encoded as absorption/reflection of incoming packets At the WiFi reader: how to decode the difference? WiFi packet detection ECE 1161/2161 Embedded Computer System Design 2 23
WiFi Backscatter Limitations Low data rate One bit per WiFi packet Short communication range Helper must provide strong power ECE 1161/2161 Embedded Computer System Design 2 24
Available RFID devices RFID tags With pre-loaded identifiers Available at all frequency bands RFID readers Can be used as I/O device via USB/SPI/I2C Use the starter kit for easier access WiFi/FM backscatter Fancy but adopt with caution ECE 1161/2161 Embedded Computer System Design 2 25