Bennest Precision Period Counter (PPC) system 2007/11/09 1 of 15
Contents
1. HEX EEROM contents ASC character translation EO 6C6F 7765 7374 2036 lowest 6 El 3420 6279 7465 7320 4 bytes E2 4E4F 5420 5553 4544 NOT USED E3 2062 7920 7468 6973 by this E4 206D 6163 6869 6E65 lt lt old values machine E5 2E41 4C4C 2061 7265 ALL are E6 2075 7365 722D 6465 user de E7 6669 6E65 642E FFFF fined E8 2863 2932 3030 3620 c 2006 E9 6A2E 722E 6265 6E6E 3 Yr benn EA 6573 740D OA0A 3153 est 1S EB 6F6C 6F50 7063 2063 oloPpe c EC 616C 2040 2032 3043 al 20C ED ODOA FFFF FFFF FFFF EE E70F 1A58 E5C8 0A33 EF 323C 2105 3200 OOFF EO 6C6F 7765 7374 2036 lowest 6 El 3420 6279 7465 7320 4 bytes E2 4E4F 5420 5553 4544 NOT USED E3 2062 7920 7468 6973 by this E4 3031 3233 3435 3637 lt lt new values 01234567 E5 2E41 4C4C 2061 7265 ALL are E6 2075 7365 722D 6465 user de E7 6669 6E65 642E FFFF fined E8 2863 2932 3030 3620 c 2006 E9 6A2E 722E 6265 6E6E 3 r benn EA 6573 740D OAOA 3153 est ise EB 6F6C 6F50 7063 2063 oLoPpe a EC 616C 2040 2032 3043 al 20C ED ODOA FFFF FFFF FFFF EE E70F LASS E5C8 DASS EF 323C 2105 3200 OOFF Bennest Precision Period Counter PPC system 2007 11 09 120 15 DRAFT USER CONTROL BYTES Eight bytes stored at line F are defined as follows2. EF 323C 2105 3200 OOFF A amp txbuffer fill character error indicator R S undefined reserved for future usage qn max sensor current 6 5 mA SEN undefined reserved for future usage oo Pint pressure meas t time 330 mS AG Tint temperature meas t time 600 mS A New a nnn nn nnn Sint sensor warmup time 500 mS line number i e line E From recent program source file T EPROM default contents ORG 0x2100 point to start of EEPROM templates Euser de lowest 64 bytes NOT USED by this machine de ALL are user defined ORG 0x2140 Ebuf de SP5e jr bennest 0x0d 0x0a Bid de OxOa S70929 Seppe Ox0d 0x0a ORG 0x2170 keep the calcos as high as possible be careful not to accidentally overwrite Ecofs de Oxe8 Oxde 0x18 0x06 Oxe8 Oxeb 0x08 Oxee define eight bytes user controls Eusr de 37 10 ms counts sensor warm up time Sint de 00 10 ms counts temperature meas t period Tint de 80 10 ms counts pressure meas t period Pint de 0 to be defined de 60 upper bound steady sensor current 6 5 mA approx scaling 256 33 mA 130 uA count de 0 to be defined de 0 to be defined de 0 to be defined Note in this example that Tint has been set to zero This inhibits the PPC channel from measuring a signal on the absent temperature input output data string reports only 4 byte pressure datum
3. Bennest Precision Period Counter PPC system 2007 11 09 13 of 15 DRAFT Warning Setting the temperature and or pressure measurement times to extreme values may Cause strange behaviour software doesn t error check these values Known limits values between 330 mS and 1200 mS are acceptable Test carefully if values outside this range are desired Example Send Y PPEF64646405320000FF lt cr gt to set Sint Tint Pint 1000 mS 64 hex 100 decimal WARNING DO NOT CHANGE VALUES STORED AT LINE E THESE ARE UNIQUE CALIBRATION CONSTANTS WHICH CONTROL THE INTERPOLATOR FUNCTIONS It is recommended that the user use the PPD command to view and record these values in a safe place Keystroke errors happen Bennest Precision Period Counter PPC system 2007 11 09 14 of 15 DRAFT Interconnect cable pinouts 2 pin 1 RD 2 BK 3 pin 1 BK 2 RD 3 ne 4 pin 1 BK 2 RD 3 OR 4 YL 8 pin 1 GN 2 OR 3 BN 4 WH 5 OR 6 WH 7 BU 8 GY RTD or thermistor RTD GND IN battery GND xx double crimp with shield drain wire 7 2V nominal ABMAX 15 volts sensor GND 6V sensor common sensor power temperature signal pressure signal logger data aux power sync VEXT VEXT GND uxiliary power input to system twisted pair ABMAX 30 volts paired with GY RX_EXT4 RX_EXT twist
4. OAOA 3153 Ascii strings sent at powerup EB 6F6C 6F50 7063 2063 for software ID purposes EC 616C 2040 2032 3043 ED ODOA FFFF FFFF FFFF EE E70F 1A58 E5C8 0A33 DO NOT CHANGE THESE BYTES EF 323C 2105 3200 OOFF timing control bytes see below A line number in Hex B send command string PPS lt cr gt to resume normal operation CHANGING PPC EEROM CONTENTS All EEROM contents can be overwritten EIGHT BYTES AT A TIME by sending a string in the following form ds PPEnkkkkkkkkkkkkkkkk lt cr gt i Rahs AVE tees gt eek wage ae T ight HEX bytes data payload line number in Hex command header A AAAA IMPORTANT overwrite command executes upon reception of trailing lt cr gt All eight data bytes 16 characters MUST be entered if data string is shorter than eight bytes trailing garbage characters will be written to EEROM Helpful hint it is OK to send a couple of extra characters at the end of the command line prior to the lt cr gt i e PPEF64646405320000FF00 lt cr gt Bennest Precision Period Counter PPC system 2007 11 09 11 of 15 DRAFT Example To overwrite contents at line 4 Send PPE43031323334353637 lt cr gt command will DUMP the original contents overwrite the selected line then DUMP the new contents
5. of the card see Fig 1 SENSOR POWER PROTECTION PPC provides 6 8 volts to sensor Sensor current is sampled during its power up and if it exceeds a programmable threshold nominally 6 mA the sensor power will be disconnected Data is reported as FFFFFFFF hex to signal this condition KNOWN BUGS NUISANCES PPC ascii output mode only IF signal is absent on pressure input data output ceases With temperature measurement enabled then IF pressure signal present but no temperature signal temperature signal is reported as all zeros COMMAND STRING DEFINITIONS see next page for explanations PPD lt cr gt Dump the EEROM contents PPEnkkk kkk lt cr gt Enter revised EEROM data at line n Bennest Precision Period Counter PPC system 2007 11 09 LO of 15 DRAFT VIEWING PPC EEROM CONTENTS Various control bytes stored in EEROM can be viewed and edited A To view these bytes send command string PPD lt cr gt default contents shown EO 6C6F 7765 7374 2036 El 3420 6279 7465 7320 E2 4E4F 5420 5553 4544 these eight lines 64 bytes total E3 2062 7920 7468 6973 are NOT used for control and can E4 206D 6163 6869 6E65 be freely redefined by the user E5 2E41 4C4C 2061 7265 e g for instrument ID purposes E6 2075 7365 722D 6465 E7 6669 6E65 642E FFFF E8 2863 2932 3030 3620 E9 6A2E 722E 6265 6E6E EA 6573 740D
6. 0 1 0 0 3300 3600 3900 4200 seconds Bennest Precision Period Counter PPC system 2007 11 09 2 of 15 DRAFT Fig 1 A minimum system top front view RTC PPC card with RS232 adapter attached say y a to sensor from battery RS232 adapter VC TXO trim Fig 2 A minimum system top rear view RTC PPC card with RS232 adapter attached RS232 adapter from battery to sensor Bennest Precision Period Counter PPC system 2007 11 09 3 of 15 DRAFT j hes inc LT i mensions d all OUTLINES WAWIXOW AJOLS Cabo ISYB RE e ETE ddd TINA es 2 NES 99d Tena ass odamna 9Se e Zeya __ 289 ddd TN Sag a SSeS Te dis Lu 290 1 ee ON SE 12 2S86e26 adIyiS L3BNHSOS Agee 139507 gas gg g g Je ewe Ip KGa kiA SILY Bul UNOowW BIC BEE D o2 wae LL LES gge d 1 Ol1dl Lv Gre GSB e2 09 m a Q 0 al E EE S co A Q al al Q 2a a 2 9 piece ce Sl 0 sin _ e PP aan Y SR S S 38 1 F L R Be as ce Stare ke aso ova E a yx aso sin x 25 O OL LLAPZENA ugo Fil DI ago aarsese aoe cedure c onde X g SL HHgee pl o E a Sruuas cooe ecesstors 8 Zz es 7 Dis ug as Lu a ALTTO 3 E Y a So im 19 2 9 yu np i a a v uge od aur
7. 20 636C 6F63 are NOT used for control and can E4 6B20 736F 6674 7761 be freely redefined by the user E5 7265 2E41 4C4C 2061 e g for instrument ID purposes E6 7265 2075 7365 722D E7 6465 6669 6E65 642E E8 0102 50FF F380 F9FF of PPCs sample interval delays E9 0900 0000 0000 0000 PPC presence table EA 0000 0000 2437 6852 EB 5443 2032 3030 3730 see user manual for details EC 3930 370D OAFF FFFF ED FFFF FFFF FFFF FFFE EE 1407 0907 173B 3200 start time EF 0000 0000 9600 4B00 rate control OO Se non functional factory ID NS ees Sa AAA control byte a line number in Hex B send command string T lt cr gt to resume normal operation CHANGING RTC EEROM CONTENTS All EEROM contents can be overwritten EIGHT BYTES AT A TIME by sending a string in the following form A Enkkkkkkkkkkkkkkkk lt cr gt NS RL OR NO CeO A ight HEX bytes data payload ds line number in Hex Oe command header IMPORTANT overwrite command executes upon reception of trailing lt cr gt All eight data bytes 16 characters MUST be entered if data string is shorter than eight bytes trailing garbage characters will be written to EEROM Helpful hint it is OK to send a couple of extra characters at the end of the command line prior to the lt cr gt i e E8010250FFF380F9FFOO0 lt cr gt See user manual for full details See below for equivalent PPC EEROM operations Bennes
8. B1 7D6E3840 O 4 byte averaged thermometer data ION 4 byte binary timestamp PES 10 bit supply voltage SE 10 bit battery current YYYYMMDDHHMMSS ascii timestamp software version ID AMA 5 see file RTCboot txt for more 6 disconnect power when done POWER OPTIONS PPC consumes 60 mW in continuous operation single channel The PPC is designed to operate from either a 6 volt SLA battery or a 7 2 volt lithium battery connected at the battery socket but 9 volt or nominal 12 volt batteries are also OK see below Overcurrent protection PTC may trip if battery voltage exceeds the 15 volt threshold of a protection zener IF AC power is available a small 12 VDC wall wart may be connected at the flying lead from the RS232 adapter This power input has polarity over voltage and over current limiting and will provide the PPC with a regulated nominal 7 8 volts diode summed with whatever battery is connected Note that if battery voltage is greater than 7 8 volts battery will power the card whether or not the AUX POWER input is active Bennest Precision Period Counter PPC system 2007 11 09 5 of 15 DRAFT INTERMITTENT operation In isolated deployments operating from a battery pack the power consumption of the system will likely determine the sample rate ina complex tradeoff between battery life sample rate and integration measurement duratio
9. DRAFT General A new pressure period counter PPC used with a Paroscientific Digiquartz Pressure Sensor provides higher resolution temperature compensated pressure data than has previously been available for deep ocean observations Pressure resolution of lt 30 ppb full scale at 1 Hz has been realized System data are stored on a compact flash card maximum 1 GB and can be downloaded on site Each system comprises 1 to 9 PPC channels and sensors a real time clock RTC a serial to compact flash logger SCF and batteries History An investigation began in late 2003 to determine whether a period counter circuit could be designed with improved resolution noise and power consumption which would be of significant benefit to the earth and ocean science community The PPC results from this work Several prototype units using a preliminary algorithm were deployed in September 2004 for an IODP CORK borehole observatory program with the following operating properties Pressure period measurement noise lt 10 ppb 800 ms integration time 1 Hz sampling Relative pressure resolution lt 100 ppb full scale 800 ms integration time Temperature period measurement noise lt 1 ppm 400 ms integration time Absolute pressure accuracy temperature compensated lt 1 ppm full scale Average power dissipation lt 30mW 4 channels 1 minute sampling Note 100 ppb resolution equates to 0 4mm head for a 4000 m sensor Current status Recent algo
10. Sluuaee FED UTD vda FED Ep u a D be ey a 3 A dt ag ae a 8 ugar ain e P wi amp sueazscon 50 u e vu S B ASEEMEOL 3 i B aaz 5 Sol en 3 su er2cam1son oDe TE ugar SED os 7 i 2 y ig E oa 7 a Y deus ERA a O I is xe 2 224 694 y PR y rie og LS usxaar zeny IQ 81 VERE a3 2x E pe estaa E Dz se 2 A Xx o D Y Isl Y Y ORN N vossue 220 oa 051 7 sen ee vap a Eze per o D om 80 Bary Y eenteD mz ES eer sou gt EN yate Doy G10 S a au 5 D2 0 0 IS go LL o sin amp Bl ol ai FAB J Dipl ya9don la ST IS aaen 9S4 O 819 usxneizenyP IRAN ye s T 619 3 POOR 5 amare o DAIS DOW iggy Geo Oy COS BRKT ND e av SNE ols ae 2 s84 amp 2 S18 vr seu y om O ano Ada gO lg r T zes ea eo Qoa w unl E n i Laat aNgo 3 sa ly NER awda uz att 25 Ierveanxz Bre 9 E ZrO mermar da tral E sere Da MECHANICAL 4 of 15 PPC system 2007 11 09 Period Counter ision Bennest Prec DRAFT QUICK START OPERATION with RS232 dongle attached ali connect sensor pinouts listed on last page Des connect RS232 plug to computer serial port run Hyperterminal or similar terminal program set up for 8N1 19200 baud oF connect PPC power either battery or AC adapter 4 observe 1 Hz data sentences 7h14070908000237 047226250701AF 7D6E6B2A 7h14070908000238 051213250701B0 7D6E011E 7h14070908000239 053211250701
11. ed pair TX_EXT4 TX_EXT 1HAz1 O S422 data from logger twisted pair external 1 Hz timing signal to RTC a RS422 commands to logger R end of document 2007 11 05 Bennest Precision Period Counter PPC system 2007 11 09 15 of 15
12. er enable send Q to disable goto CR_N N toggle NepEnbl flag send Q to disable goto CRexit HERO goto CR_P P PPC enable PPC passthrough in NORMAL mode goto CR_Q Q Quit ie power down the PPC circuits goto CR_R R Resume PPC enable PPC passthrough in CALIBRATE mode goto CR_S S Set the clock registers with values in top EEPROM goto CR_T T Time display one sentence per second goto CR_U 7 U Up the time advance one second goto CR_V V down the time retard one secondo goto CRexit W goto CRexit X goto CRexit HE goto CRexit Na T CRexit goto sp_1 all undefined commands hop back into outer routine Note that K L commands will execute at the next edge detected on the 1HZ_I O pin Be careful with these commands they can alter the clock s internal time Commands Q or control C will abort any pending sync operation Commands M and N are toggles but Q will cancel Factory use only Commands U and V will shift the clock s time in one second steps Bennest Precision Period Counter PPC system 2007 11 09 7 of 15 DRAFT VIEWING RTC EEROM CONTENTS Various control bytes stored in EEROM can be viewed and edited A To view these bytes send command string D lt cr gt default contents shown EO 6C6F 7765 7374 2036 El 3420 6279 7465 7320 E2 4E4F 5420 5553 4544 these eight lines 64 bytes total E3 2062 79
13. inimize nuisance switching this switchover will only occur after two or three successive voltage measurements have met the above requirements In NEPTUNE mode the RTC is testing the voltage once per second so reversion to INTERMITTENT mode will occur within 2 or 3 seconds Once in INTERMITTENT mode however the RTC is only testing at the programmed sample rate If for instance this has been set to 30 seconds the NEPTUNE switchover may not occur for 60 or 90 seconds Bennest Precision Period Counter PPC system 2007 11 09 6 of 15 DRAFT RTC COMMAND SET sending control C lt cr gt will always return the user to the default RTC timestring state From recent software CRjump jump table send to various routines depending on leading character in received serial string clrf PCLATH to guarantee we re pointing to this lowest subpage addwf PCL f note input characters MUST BE UPPER CASE goto CRexit A goto CRexit B goto CRexit PES goto dumpEE 7 D Dump EEPROM contents goto writeEEblock E EEPROM write command goto CRexit iste goto CRexit G goto CRexit JH goto CRexit A i goto CRexit yoa goto CR_K K sync to rising edge IO1HZ may cause loss of 1 second goto CR_L L sync to falling edge I01HZ may cause loss of 1 second goto CR E toggle 1Hz driv
14. n Longer integration times provide quieter measurements at the expense of power consumption See the MLCORK operating manual for details of the programmable features of the system 1 Hz NEPTUNE operation FEATURE ADDED 2007 09 01 When ample power is available the PPC unit can operate at a 1 Hz sample rate with fixed PPC parameters that implement a best possible measurement of the pressure input signal In NEPTUNE mode the PPC channels are powered continuously and every input signal edge is utilized for lowest possible noise ct ct NEPTUNE mode is available to the user in several ways Setting the NEPTUNE control byte in the RTC EEROM to 00 hex will force the unit into NEPTUNE mode independent of input voltage Similarly setting the NEPTUNE control byte to FF hex will force the unit into intermittent mode independent of input voltage IF the NEPTUNE control byte in the RTC EEROM is set to 8C hex then the unit will automatically switch into NEPTUNE mode and back to NTERMITTENT mode depending on the apparent input voltage The RTC monitors its available input voltage diode summed as described above If the voltage exceeds the threshold established by the 8C control byte then NEPTUNE mode is enabled If the voltage subsequently drops below the threshold the unit will revert to NTERMITTENT mode In an attempt to m
15. rithm improvements see plots overleaf provide the following performance PPC features Pressure period measurement noise lt 3 ppb 800 ms integration time Relative pressure resolution lt 30 ppb p p full scale 800 ms integration time Power dissipation per channel during measurement cycle 42 mW 0 mW when sleeping RTC features Maximum sample rate 1 Hz Clock accuracy 4 ppm 2 min yr Power dissipation sleeping lt 1 mW Power measurement cycle lt 5 mW SCF Minerva logger features Communications hardware RS422 RS232 Communication rates 4 8 to 230 4 kBaud Download protocols bytes packet custom 512 Xmodem 128 streaming Further information available John R Bennest ph fax 250 494 5145 Bennest Enterprises Ltd PO Box 1092 mail 12438 Victoria Road South SUMMERLAND B C CANADA VOH 1Z0 Bennest Precision Period Counter PPC system 2007 11 09 1 of 15 DRAFT PPC resolution vs standard period counter Paroscientific Model BB4000 2 s n 94223 lab air pressure and temperature raw data 800 ms integration e ii sean socia MR r relative pressure ppm E i Mod Wo ALT Y standard period counter 0 300 600 900 1200 1500 1800 seconds PPC thermal stability WE ee err 0 9 lt 30 ppb peak peak noise standard period counter o 2 D N relative pressure ppm o mn 0 4 0 3 signal source calibration TCXO 0 2 raw data 800 ms integration
16. t Precision Period Counter PPC system 2007 11 09 8 of 15 DRAFT BINARY DATA FORMAT Captured with MLTERM from a solo RTC PPC T card sampling every two seconds 24fca8b2 757d79b5 3fffff8c 24fca8b4 715747956 3fffff95 AKAAAAAA 4 byt pressur datum AAAAAA 3 byte thermometer datum AA l byte RTC unique ID AKAAAAAAA 4 byte timestamp PPC DATA DECODING pressure datum from example above interpret the 3FFFFF95 as follows pressure signal period in microseconds 20 1 hex2dec 3FFFFF95 2 32 Note that PPC will only correctly measure input signals with periods ranging between 20 us and 40 us 50 to 25 kHz frequency b temperature datum when enabled temperature signal channel includes divide by 4 prescaler prescaled signal is then processed by PPC circuit identically to pressure signal therefore temperature signal period in microseconds DS 1 hex2dec 375B7169 2 32 Bennest Precision Period Counter PPC system 2007 11 09 9 of 15 DRAFT PPC ABSOLUTE CALIBRATION Unit is factory adjusted to be within 0 1 ppm at 2 degC User can adjust the 12 8 MHz reference VC TXO if desired substitute a known signal frequency for pressure input o must be AC coupled o 3 to 5 V p p amplitude square wave preferred make adjustments with the blue multi turn trimpot located near the center of the top edge
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