Downloaded 37 times
Uploaded byOpenEnergyMonitor
OSHUG #26 Low Power Wireless Sensors
Low Power Wireless Sensors can provide concise environmental monitoring through small, low-power nodes. The document discusses wireless considerations for such nodes using standards like 868MHz. It then describes the hardware and software used in open-source monitoring nodes, including microcontrollers, wireless modules, and power optimization techniques. Practical applications discussed include home energy and temperature monitoring, heat pump oversight, and bee hive observation.
More Related Content
Similar to OSHUG #26 Low Power Wireless Sensors
OSHUG #26 Low Power Wireless Sensors
- 1. Low Power WirelessSensors Glyn Hudson @openenergymon OSHUG #26 16/05/13 ...and their role in helping us build a sustainable future
- 2. 2 Open-source sustainable technologies Technologythat empowers us to participate in creating a future where we live within ecological limits. openenergymonitor.org
- 3. 3 Sustainable Energy Tools tohelp us work towards sustainable energy in a way that adds up. Energy Stacks based on David MacKay's book: withouthotair.comTrystan's Stack 2012 Only 17% Sustainable Energy 2030 Target* 2012 UK Average 2012 Trystan *CAT zerocarbonbritain.com/
- 4.
- 5.
- 6.
- 8.
- 9. 9 An open-source web-appfor processing, logging and visualising energy, temperature and other environmental data ●Open-source, downloadable and installable on your own server (e.g RaspberryPi) ●Specifically designed with processing and visualising energy data in mind. ● Written in php, mysql, javascript and jquery ● Follows MVC architecture emoncms.org openenergymonitor.org/emon/emoncms github.com/emoncms
- 10. Visual Dashboard Editor Drop& drop, customisable graphs, re-sizeable widgets, buttons and live feeds
- 11. 11 Contents Technology of awireless node - Wireless considerations - Wireless Module Hardware - Mircrocontrollers - Low power optimisation - Battery Life Estimation Practical Examples - Home Temperature and Energy Monitoring - Home energy modelling & simulation - Heat Pump Monitoring - Bee Hive Temperature Monitoring The Future - Current Hardware Prototypes Live Demo?
- 12. 12 Wireless Considerations –ISM bands ● Industrial Scientific and Medical ● Licence exempt ● 433Mhz, 915Mhz, 868Mhz and 2.4GHz ● Commonly used for low power, low range wireless transmission ● Applications need to be interference tolerant ● 433/868/912MHz - Restricted duty cycle <10% ● Lower frequency's have less free space attenuation and better propagation – better range 2.4GHz 433MHz / 868Mhz / 915Mhz Wifi Doorbells Bluetooth Security Systems Zigbee Cordless telephones Weather Stations
- 13. 13 Low Power WirelessModules RFM12B (HopeRF) SRF (Ciseco) TI - CC1110 XBEE (Digi) NRF24L01+ (Nordic Semi) Interface SPI Serial / SPI Serial SPI Freq 868 Mhz 868 Mhz 2.4GHz 2.4 Ghz AES Encryption NO YES YES NO Power Supply 2.2V - 3.8V 2.0V - 3.6V 2.1V – 3.6V 1.9 – 3.6 V Rx / TX Power 14 / 23mA 20 / 36.2mA 35/ 38mA 11.3/13.5ma Sleep mode 1 132.2ua @ 2.6v 26uA Sleep mode 2 0.3uA 0.2uA @2.6v <1uA <1uA (900nA) Price (inc VAT) x1 May 2013 £4.79 £11.52 made in UK! £17 £4 Regulatory Approval FCC/ETSI No In Progress Yes No http://blog.homelabs.org.uk/wireless-connectivity/
- 14. 14 Microcontrollers ● Ciseco RFu– ATmega328 MCU plus SRF / RFM12B radio in XBEE form factor ● Designed & made in UK ATmega328 with Arduino Uno bootloader + commonly used + easy to develop for using Arduino IDE + easy to upload code and debug + active community - not the most low power option, but not too bad: 6.8mA running @ 16Mhz 3.3V 4.6uA while sleeping
- 15. 15 emonTx / emonTx Arduino Shield Energymonitoring node emonTx Low Power Temp Semi – populated emonTx with 2 x AA and DS28B20 temperature sensor NanodeRF Web-connected base station - Arduino clone with ENC28J60 Ethernet and RFM12B wireless onboard RFM12Pi RFM12B wireless Raspberry Pi expansion board. Uses Pi's Serial UART GPIO pins OpenEnergyMonitor Modules – ATmega328 & RFM12B wireless
- 16. 16 http://nathan.chantrell.net/tinytx-wireless-sensor/ ATtiny84 Based Nodes x http://harizanov.com/wiki/wiki-home/funky/ http://jeelabs.net/projects/hardware/wiki/JeeNode_Micro +Cheaper and smaller than ATmega328 + easily run off internal 8Mhz oscillator + Can use Arduino IDE (with some tweaks) - Does not support hardware serial - Requires ISP programmer to upload code - Harder to debug Examples with DS18B20 temperate sensor and DHT22 Humidity Sensor TinyTX – Nathan Chantrell Funky Sensor – Martin Harizanov JeeNode Micro – JCW JeeLabs
- 17. 17 Low Power Ticks- software ● AVR sleep mode – Disable all unneeded functions (e.g ADC) and put processor to sleep – Reduce current consumption from 6.4mA to 4.6uA ● Requires internal watchdog timer or external interrupt to wakeup ● Radio should also be put to sleep – if not needed for receiving packets – 14mA (Rx) / 23mA (Tx) reduced to 0.3uA when sleeping for RFM12B * Running @ 16Mhz 3.3V - 6.4mA * SLEEP_MODE_IDLE -the least power savings (2.8mA * SLEEP_MODE_ADC * SLEEP_MODE_PWR_SAVE * SLEEP_MODE_STANDBY * SLEEP_MODE_PWR_DOWN -the most power savings (4.6uA) https://github.com/jcw/jeelib/blob/master/Ports.cpp http://jeelabs.org/2011/06/26/current-measurements/
- 18. 18 Simple Low PowerRFM12B example ● Simple sketch to send out an ever increasing integer once every minute ● Estimated battery life of 3 years on a single 1300mAhr 3.3V LiPo battery – ATmega328 @ 16Mhz, approx average current draw <57uA http://jeelabs.org/2013/04/18/9-50-days-and-counting/ JeeLabs Real word test, 2.5 years and still going!
- 19. 19 Battery Life EstimatorTool http://oregonembedded.com/batterycalc.htm
- 20. 20 Low Power Tricks- Hardware ● Turn off sensor in-between reads – e.g. DS18B20 VCC powered from MCU digital I/O ● Don't use a voltage regulator – Eliminate quiescent current draw: MCP1702 1.6 uA , LM7805 5-8mA!) ● DC-DC boost converter ● Disable ATmega BOD – Arduino default is 2.6V (Brown Out Detection) ● Slow down – ATmega328 can work down to 1.8V with 4Mhz clock – default is 16Mhz ● Energy harvesting – Mini solar PV – Battery less operation – Super capacitor – PFET to disable RFM12B at startup Energy consumption of RFM12B packet transmission with ATtiny84. Duration 5.7ms, average: 10mA, peak 25mA http://jeelabs.org/2010/09/03/jeenode-goes-solar/ http://harizanov.com/2013/04/scope-screenshots/
- 21. 21 Practical Example –Home Temperature Monitoring
- 22. 22 Home Heating EnergyInput & Temperature Monitoring January 2011 - April 2013
- 23.
- 24.
- 25.
- 26.
- 27.
- 28. 28 Heat Pump Monitoring JohnCantor, heat pump consultant ● Remotely monitor heat pump performance ● Identify problems ● Optimise control by providing feedback www.heatpumps.co.ukhttp://openenergymonitor.org/emon/applications/heatpump
- 29.
- 30. 30 RF Link Ambient Temp probe Solar PV Battery Core temperature probe Winter2010 Bee Hive Monitoring Clive Hudson, Meirionnydd Bee Keepers http://openenergymonitor.org/emon/beehive/v2
- 31. 31 A 'normal' beetemperature week
- 32. 32 The Future -Hardware Prototypes emonTH TEMPERATURE & HUMIDITY open hardware emonTxV3 energy monitoring node openenergymonitor.org open hardware ● SMT design ● Enclosures
- 33.