IEEE Module

Transcription

1 Design of a Versatile Low-cost IEEE Module for Long Term Battery Operation Alexander Klapproth, Stefan Knauth and Rolf Kistler HTA Luzern - Lucerne University of Applied Sciences CEESAR - Centre of Excellence for Embedded Systems Applied Research Contact: Prof. A. Klapproth alklapproth@hta.fhz.ch EuZDC 2007 Lucerne University of Applied Sciences / Slide 1

2 CEESAR Research Center Center of Excellence for Embedded Systems Applied Research Lucerne University of applied Sciences Building & Home Automation Embedded Control and Realtime Wireless Indoor Localisation Lowpower-Lowcost Solutions. Strong background in research & development cooperations with industry partners Researchproject funding possible depending on topic, risks and goals EuZDC 2007 Lucerne University of Applied Sciences / Slide 2

3 Overview ZigBee for the aware home fire & smoke detector motion detector door control window control heating / cooling energy monitoring & control Benefits: > more comfort > less energy consumption > enhanced security lighting control remote control Source: Texas Instruments Inc. EuZDC 2007 Lucerne University of Applied Sciences / Slide 3

4 Contents Design of a Versatile Low-cost IEEE Module for Long Term Battery Operation Introduction Hardware Components Design Applications EuZDC 2007 Lucerne University of Applied Sciences / Slide 4

5 Requirements Initial Vision: Autonomous Radio Device for Sensor Applications Low-Power Durability >= 10 Years, Stand-alone alone Small Minimal Footprint Open Standards based on PHY/MAC layers, full access to resources, freely programmable Low-Cost For large quantities (> pieces/year) Production cost < 10 EuZDC 2007 Lucerne University of Applied Sciences / Slide 5

6 Make or Buy? Make (RF-IC, SoC) if High quantities Medium/long term project High cost pressure Sophisticated system requirements Have access to required competence and support Full application integration Buy (Module) if Low quantities (typically <20k units) Short time-to-market Low initial costs Basic system requirements Lack of RF competence >> Depends on the project, requirements and company >> Looking at the requirements: Make Source Criteria: Texas Instruments Inc., Cirronet EuZDC 2007 Lucerne University of Applied Sciences / Slide 6

7 Building Blocks Interface Periperals, GPIOs Antenna Power Source MCU Firmware RF-IC Balun, Match Feed CLK Source EuZDC 2007 Lucerne University of Applied Sciences / Slide 7

8 SoC, SIP, RF-IC, NwkProc? SoC (System-on-Chip) SoC MCU, RF-IC Usually results in smaller footprint Close coupling of MCU and RF-IC Stack, Application less overhead good performance/power consumption SIP Small number of external components MCU RF-IC Simple system design Stack, Application Low system bill-of-materials costs MCU/RF-IC Tandem Flexibility Use your processor and environment Choose the RF frontend you like RF-IC may have better radio characteristics Hybrid Systems: Network Processor -> ZigBee on RF-IC SIP -> MCU & RF-IC in one package not on same die MCU/RF-IC MCU Stack, Appl. NwkProcessor MCU Appl. RF-IC RF-IC Stack EuZDC 2007 Lucerne University of Applied Sciences / Slide 8

9 SoC/SIP: Selection Criteria (1) There are a lot (of differences) EuZDC 2007 Lucerne University of Applied Sciences / Slide 9

10 SoC/SIP: Selection Criteria (2) Taking the specific requirements! EuZDC 2007 Lucerne University of Applied Sciences / Slide 10

11 Antenna: Types (1) Chip Whip PCB 1. Size 2. Cost 3. Performance Remarks - Assembly, fitting, mounting Design crucial, orientation issues Chip antennas have a reasonable performance compared to their size EuZDC 2007 Lucerne University of Applied Sciences / Slide 11

12 Antenna: Fractus Chip Antenna Performance Criterias High, stable Bandwith Good omnidirectional radiation pattern Reasonable Gain High Efficiency Stable Impedance Fractal Technology Space-Filling, multiple-scale geometries Performance optimisation of multilayer antennas Standard materials and processes Other chip antanna provides Antenova: Rainsun: EuZDC 2007 Lucerne University of Applied Sciences / Slide 12

13 Balun, Match & Feed Line Balun Feed Ballanced to Unballanced General: Achieve compatibility between two components or systems Here: Convert the differential SoC RF output to the single-ended antenna Match Balun Z SoC RF out = Z Antenna = 50 Ω Balun No active matching circuit it needed d Feed Line Z SoC RF out = Z Feed = Z Antenna = 50 Ω Feedline must have 50 Ω Can be realised with surface microstrips and/or as passive electric circuits (LC). Trade off between number of components and footprint Match EuZDC 2007 Lucerne University of Applied Sciences / Slide 13

14 Feed Line Calculate the dimensions of the microstrip Freeware AppCAD from Agilent: EuZDC 2007 Lucerne University of Applied Sciences / Slide 14

15 Energy Source Lithium Battery Cell Standard Component Used in Photocameras High Energy Densitiy Sufficient Discharge Current Coin cells can t provide 27mA Low self discharging g constant No voltage regulation needed Easy to fit (solder flags) Alternatives Ambient energy harvesting Accumulators, super capacitors Inductive energy transmission EuZDC 2007 Lucerne University of Applied Sciences / Slide 15

16 Layout 24GH 2.4 GHz HFD Design Rules Ground planes The bigger the planes the better Solid ground plane below the chip Vias Close to decoupling capacitors Vias on the ground pad under the chip Several vias to connect layer grounds Components Place two coils 90 to each other Use exact same values Microstrip Distance 2 times it s width from anything Length min. Lambda / 4 Antenna Move away from circuitry Antenna clearance zones Follow the reference designs! Sources: Texas Instruments Inc., Fractus EuZDC 2007 Lucerne University of Applied Sciences / Slide 16

17 Verification HF design needs to be verified Return Loss Span 200 MHz Span 500 MHz Radiation Pattern Horizontal Vertical Packet Burst Radiation Frequency Spectrum EuZDC 2007 Lucerne University of Applied Sciences / Slide 17

18 Software: ZigBee, IEEE or Proprietary? Options Pros Cons ZigBee - NWK only - Multi-hop routing - Ressource usage - APS, ZDO - Tree, Mesh - Execution time - Profiles - Mgmt. Functions - Packet overhead -Interoperability -Licensingg IEEE MAC IEEE PHY -Simple MAC - Reduced MAC - Full MAC From very simple to fully featured - Node addressing - PAN associateion - Channel Access - Security - Acknowledges compliant - Fits 100% the requirements - Not ZigBee - No NWK Layer - Packet overhead - You cannot communicate with anyone else - Development time for high-level features EuZDC 2007 Lucerne University of Applied Sciences / Slide 18

19 Software: Low Power No low power without smart SW Use SW controlled hardware features Chose appropriate power mode Stop CPU during RF RX/TX Adapt the output power Switch to internal RC oscillator when radio is not used Turn off analog radio part Shut down peripherals Execute code from RAM Optimise data transmission protocol Minimise RF TX/RX on time Optimise packet length Consider data patterns Burst data if possible Consider power availability if unevenly distributed Use MAC protocol features (beacon, polling, short addresses, intra PAN bit ) Source: TI/Chipcon Design Note DN103 EuZDC 2007 Lucerne University of Applied Sciences / Slide 19

20 Application: KISS Temperature Sensor Send a temperature value to a collector every 10 min. Optimised for Low Power Star Topology Small number of nodes Simple IEEE frames No channel access Random Sleeping time + RC osc. One way transmission (no ACKs) No transmission checks Internal temperature sensor About 20 years lifetime (not proved yet) EuZDC 2007 Lucerne University of Applied Sciences / Slide 20

21 Application: Power Point Page Flipper Flip the PowerPoint slides using WeBee 3 WeBee 3 side KISS Temperature Application PC Side IEEE USB dongle from USB IA OEM DAUB Access on IEEE or PC ZigBee level e using Windows DLL ZigBee DLL Receive Message, find PowerPoint Window and Application send Windows Notification Message Windows MSG PC: 1 CCP File, 220 Lines of Code Power Point USB Dongle Drv. Custom Windows EuZDC 2007 Lucerne University of Applied Sciences / Slide 21

22 Thank you! Lucerne University of Applied Sciences Embedded systems applied research UPnP Wireless / IEEE / ZigBee Low resource platforms / Java on 8 Bit Localisation Industry research partner Partner for research consortia EuZDC 2007 Lucerne University of Applied Sciences / Slide 22