Motion Sensor based on EnOcean STM 300
Contents
1. APPLICATION NOTE 311 Green Smart Wireless MOTION SENSOR BASED ON ENOCEAN STM 300 400 1 Purpose of this application note Purpose of this Application Note is to show how to build a maintenance free ambient light powered radio motion sensor based on the EnOcean Dolphin core devices The demo concept implements the following function a lamp is manually switched on when entering the room and remains on as long as a presence is detected in the room finally the lamp automatical ly switches off within a certain time after the room is vacated The use of the multipurpose STM 300 400 enables simplified hardware due to its customer programmability 2 Motion Sensor System Description The system consists of two modules both EnOcean based a Light powered motion sensor as radio transmitter and b Line powered radio controller with switching actuator and Lamp ON push button gt a Fig 1 Ambient light powered Fig 2 STM based Motion Fig 3 Line powered TCM Motion Sensor sensor front view based radio controller 3 Principle After pressing the Lamp ON pushbutton at the controller Fig 3 its integrated timer au tomatically switches the light on for a certain adjustable time length i e for 5 minutes like a timer switch for staircase lighting The controller expects further presence messages in this time period This time is sufficient for charging the empty energy storage capacitor of the ambient2. This time period can be flexible programmed into the STM device EnOcean www enocean com Subject to modifications Christian Bach Sep 2015 Page 4 6 APPLICATION NOTE 311 Green Smart Wireless enocean STM 300 400 based motion sensor FDN306P 470uF 470uF OR 100uF 33K LPv521 33n an DO 3M3 3M3 a cf Riv R8 I Oy cia i ca i BATES4AW TS i 22 47k C5 R19 l Gain a o aR r20 in2 10n C12 C15 1M8 WXIDO 29 wa eld STM 300 400 af a ca em OL oO Su 5 Lee mi oF ui Ly 7 O 0 Q 10k 29922 RT ze e LSP6 Fig 6 Realization example simple HW principle based on STM 300 400 8 Firmware example A very simple free firmware DEMO for this STM 300 demonstrator called MotionSensor ZIP with a transmission cycle of only 5 seconds and EEP2 1 profile A5 07 01 is also provided into attachment for STM 300 DA modules only as example as is without any liability To use this Firmware following tools steps are needed E Following current tools are required o Keil C51 compiler o DolphinAPI o DolphinStudio o DolphinView o MotionSensor FW APPLICATION NOTE 311 Green Smart Wireless enocean Compile the Firmware or use the precompiled hex file from the Output Folder Using DolphinStudio program first the STM device Start DolphinView and press the learn button on the board The sensor identifies itself automatically transmit
3. V correspondingly to the STM 300 400 start up level the motion detector circuit is NOT powered so all the current generated by the solar panel i e 5 uA is available for initial charging The minimum needed storage capacitor value results using the formula C x U 2 1 xt E C gt I1xtx 2 U where 5 WA t 30 seconds U 2 6 V so C gt 120 UF needed for auto re activation E Cx0 3 V 2 25 mA x 3 ms gt C gt 500 uF for a maximal voltage drop lt 0 3 V To fulfill both conditions the greatest value has to be chosen respectively C must be gt 500 UF let s chose 680 uF Since the typical tolerance of good tantalum capacitors in this range IS 20 in worst case the capacity will be at least 544 uF 680 20 UF Finally the needed solar panel area results from the maximal current requirement 5 uA av erage current at 3 V and initial charge time start up within 5 minutes whichever current value is greater C x U 2 Ic x t where C capacity uF U voltage volt Ic charging current intensity uA and t time seconds The charging current required for start up within 5 minutes is therefore in worst case Ic UA C x U 2 x t 680 20 uF x 3 V 2 x 300 s 4 uA lt 5 uA According thus the minimum required supply current is 5 uA 50 Ix Since one transmission exhausts 3 ms x 25 mA 75 pAs every 75 seconds while the charg ing Current amount during this time is 1 uA difference between the delivered current
4. light powered motion sensor via its solar panel thereby ensuring its start up and long term function cyclically transmitting presence messages when motion detected The transmitter is an EnOcean STM 300 400 device that in the case of a motion arising sends a radio telegram at customer set time intervals only presence messages type Lamp ON Therefore each time a Lamp ON message from the radio motion sensor is received within this time period the controller timer will be re triggered and the Lamp ON time subse quently re initialized for a new period of i e 5 minutes Thus the lamp remains ON for next 5 minutes and stays switched on as long as further presence messages are received in this time period The controller SW implemented re triggerable controller timer therefore func tions as missing pulse detector for Lamp ON messages i e if no message Is received with in this preset time period the controller will automatically switch the lamp off at the end of that time period Once the lamp is switched off it can be automatically switched back on by a detection radio telegram within the next 30 seconds only Thereafter it can only be switched on by manually pressing the on button on the controller again This concept means EnOcean www enocean com Subject to modifications Christian Bach Sep 2015 Page 1 6 e APPLICATION NOTE 311 Green Smart Wireless enocean MOTION SENSOR BASED ON ENOCEA
5. right to make changes without prior notice For the latest documentation visit the EnOcean website at www enocean com
6. steadily high until VDD falls below VOFF about 2 V Thereby the motion sensor circuit will be only now continuously powered through the P channel MOSFET After every motion detection telegram the STM device wake input will be inhibited for the next 75 seconds to save energy VDDLIM is used to protect the STM 300 400 by limiting its supply voltage to VDD lt 5 V a The used motion sensor PIRI is i e a miniature PIR sensor from Murata ee IRS B340STO2 SMD micro motion detection quad Fig 5 Its output a Signal is processed by the amplifiers LPV521 Rail to Rail I O working voltage gt 1 6 V current consumption lt 0 4 uA from NS Fig 5 Only the dynamic signal component motion will be filtered and amplified by about 80 dB This amplified and filtered signal is added to a window comparator realized with two MAX920 comparators Nanopower 1 8 V upwards current drawn lt 0 4 UA open drain Their outputs are connected as a logical wired OR gate through a common 1M8 resistor to UVDD 1 8 V Therefore the high WAKE input voltage level is kept at 1 8 V without using a limiter despite the wide working voltage range 2 5 V of the motion detector circuit When a motion is detected the MAX920 output sinks to Lo and the STM device wakes up sends a Lamp ON telegram and starts its internal i e 75 second inhibit timer No further motion detection will lead now to a new wake up and radio transmission within the next 75 seconds
7. N STM 300 400 that the lamp is always switched off automatically by the controller either after a maximum of e g 5 minutes programmable time after the room was vacated or if a fault arises radio link broken independent of room vacation Additional master override EnOcean radio switches can be also implemented The practical realization of such an EnOcean i e TCM device based controller actuator is simple and therefore needs no further explanation here 4 System Requirements for the Motion Sensor Demo Minimum working environment light level at the solar cell shall be 50 Ix Please note on the ceiling you may have only about one tenth of the illumination measured on the desk Charge time start up for the energy storage capacitor shall not exceed 5 minutes in the lowest specified illumination environment Otherwise stated this time is the charge up latency time from when the lights are manually turned ON after the room was in total darkness Motion sensor shall transmit motion information to the wall box receiver i e once every 75 seconds 5 minutes after the last received motion detection telegram i e room is vacated the light will be automatically turned off The energy stored should be enough for next 30 seconds after the lights were turned off totally darkness to enable the transmitter to send a last Lamp ON telegram in case motion is detected within this time auto re activation period 5 Block Diagra
8. and the circuit current consumption without transmitting 75 s x 1 WA 75 pAs meaning the recovery condition between two transmissions is also fulfilled According to diverse data sheets for indoor solar cells i e from Sinonar Trony a 2 5 cm large single solar cell is needed to generate the needed current 50 Ix EnOcean www enocean com Subject to modifications Christian Bach Sep 2015 Page 3 6 e APPLICATION NOTE 311 Green Smart Wireless enocean MOTION SENSOR BASED ON ENOCEAN STM 300 400 Voltage considerations the operating voltage of the chosen module should be selected so that the power point voltage is near the required operating voltage of the application The required voltage of gt 2 9 V 50 Ix due to an additional serial Schottky diode voltage drop is assured by 8 serially connected single cells according to the same data sheets The last sentences give the following essential key data for the indoor solar panel gt 2 5 cm single cell current requirement x 8 cells voltage requirements thus giving an effective solar panel area of gt 20 cm One single Sinonar SS 5649 solar panel 8 cells 27 cm would deliver the required power 7 uA 3 V NOTE solar cells work as a current generator and while the output voltage is only light de pendent to the illumination over decades the current varies direct proportional with the il lumination and solar cell single area Therefore the current depend
9. ence is linear while the delivered power is not quite linear slightly reduced due to its voltage component and leak age currents influence at very low illuminations as shown below As rough conservative estimation indoors and for small area amorphous solar panels few cm an operating current in the range of 10 uA cm 200 Ix FL can be considered This value can be roughly linear extrapolated using a small derating factor for lower illuminations and or smaller area That corresponds i e to 4 5 A cm 100 Ix Additionally amorphous cells deliver indoors nominal power densities of around 4 uW cm 200 Ix respectively lt 2 UW cm 100 Ix 7 Circuit Description and Implementation of a STM 300 400 based Motion Sensor The following described concept uses the integrated new features of the STM 300 400 i e customer programmable energy management facilities and therefore is very simple Hard ware implemented functions i e ultra low power timers or voltage supervisor used by the previous implementations can be now software implemented For details please consult the latest STM 300 400 user manual After pressing the Lamp ON pushbutton at the controller the controller turns the light on for a certain time i e 5 minutes The voltage generated by the solar panel will now rise Slowly due to the empty C3 and C4 At VDD gt VON about 2 5 V the STM 300 C starts up This generates at the WXODIO CCO a Hi level that remains
10. m of the Motion Sensor Solar panel Block Diagram Motion Sensor Unit Fig 4 Block Diagram 6 Energy Balance Calculation The most important aspect of the dimensioning is to have lowest possible energy consump tion Since the energy is the product between current voltage and time this can be achieved in several ways Design and build the sensor circuit itself as frugally as possible A long time current con sumption of about 5 A 4 uA continuous 1 WA averaged for transmissions can be achieved using adequate components Ultra low power electronic devices must be chosen Therefore only PIR passive motion detectors types are suitable driven by currents below 1 uA A customer programmed STM 300 400 device periodically waked up through motion events will be used as transmitter EnOcean www enocean com Subject to modifications Christian Bach Sep 2015 Page 2 6 e APPLICATION NOTE 311 Green Smart Wireless enocean MOTION SENSOR BASED ON ENOCEAN STM 300 400 Consider 50 Ix as worst case for the solar panel Important considerations regarding energy management i e solar panel dimension ambient light conditions transmitter power and number of transmissions minute In order to maintain the required nominal transmitted power P i e range wide the only place where energy savings can effectively be made is the time factor t E P x t This means i e considering for a supply voltage of 3 V a tra
11. nsmission current consumption of 25 mA makes a power consumption of 3 V x 25 mA 75 mW From this requirement results the transmission current averaged over time A STM 300 400 radio telegram is only about 3 1000 second long e g the average power when transmitting every second is reduced by a factor of 333 actually about 225 uW e g 75 uA 3 V This still seems to be a lot but this power is what would be required if the transmission cycle were one time every second W V x Ain 1 s So if the number of messages will be limited i e to one telegram every 75 seconds which is 75 times less current consumption again i e 1 uA as long time averaged current by sending one message every 75 seconds Energy storage capacity value requirements Not too large so that a start up voltage of 2 6 V can be reached within i e 5 minutes after switching the light on 50 Ix This should ensure that the motion detector is operational within this time period On the other side the storage capacitor value shall be large enough to assure full recovery of the energy between two consecutive messages i e maximal volt age drop on the storage capacitor lt 0 3 V i e from 3 V to 2 7 V during one transmission to assure the full recovery between two transmissions and function of the sensor and also to work properly at least 30 seconds after the light is switched off auto re activation period Important please note that until the capacitors are charged to 2 6
12. ting its EEP in the LRN telegram see screen shot below E Monitor the motion detection using the EEP View as showed below DolphinView Basic 3 1 0 0 Expires 31 12 2011 File View Window Help COM3 EOTKGWOJA GATEWAYCTRL 2 3 0 0 vf lt Q Connect F5 fle DisconnectiFe f Firmware Download Node List EEPView Remote Management Statistics Telegram Analyzer Telegram Transmit H Export Profiles eep2 1 xml X G Reload XML Chart time resolution 1 minute a Workspace Count 1 EnOcean Equipment Profile ID 00801974 RORG 0xA5 4BS Telegram ull vevice_1974 EEP FUNC 0x07 Occupancy Sensor TYPE 0x01 Occupancy Learn Telegram Time 2011 4 15 18 08 42 121 EEP A5 07 01 Manufacturer EnOcean GmbH 008 Data Telegram Interpretation v Unassigned Count 6 LRN Bit Data telegram i 18 09 20 18 03 30 A PIR Status PIR off 255 18 08 50 18 09 00 18 09 20 18 09 30 Description irecti ID i TimeDiff Signal 34 dBm 18 08 42 574 00801974 4B5 00 00 00 452 Tipt z5 18 08 47 649 00801974 4B5 r j 00 00 05 075 18 08 59 237 00801974 4B5 00 00 11 587 Fig 7 DolphinView monitoring data from Motion Sensor Demo Disclaimer The information provided in this document describes typical features of the EnOcean radio system and should not be misunderstood as specified operating characteristics No liability is assumed for errors and or omissions We reserve the
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