1. Pressure Logger Construction - sunny-day-flooding-project/tutorials_v2 GitHub Wiki

Tutorial Overview

The Pressure Logger is the part of the Sunny Day Flood Sensor (SuDS) that is installed in the storm drain or on a pole cut to a specific length for each specific location. The key components include the pressure transducer, the OpenLog Artemis (OLA) and Bluetooth Low Energy board (BLE) which work together to send data to the Communications Gateway. All electronics and batteries are secured in PVC housing that is waterproof.

Fully built pressure logger

Hardware & Equipment

Note: Each item has been hyperlinked to a website where it can be purchased from. Items that must be 3D printed or custom-ordered from SendCutSend are hyperlinked to the corresponding file for ordering or 3D printing. The files for such components can be found here or by clicking on the specific component.

The design files for the probe are located here and indicate which components must be custom-ordered or 3D printed, and include the part numbers of the components that can be ordered from general vendors.

Hardware List

Name	Amount Required	Picture
Open Log Artemis	1
Proteus Carrier PCB	1
Bluefruit LE UART Friend	1
4-40 Nylon Insert Lock Nuts	9
4-40 X 7/16" Pan Head Screw	5
4-40 X 3/16" Nylon Screw	3
4-40 X 3/8" Flat Head Screw	4
4-40 X 1/2" Pan Head Screw	2
Battery Holder	1
Lower Guide Ring	1
Retaining Block (3D Printed)	1
Stainless Steel Mounting Ring	1
6-32 X 2 1/4" Pan Head Screw	1
Blue Robotics Vent and Plug	1
4-40 Nylon Hex Nut	1
D-cell Alkaline Batteries	3
2" Schedule 40 Adapter Socket X 2 NPT male	1
2" Schedule 40 PVC Pipe (cut to 9.5")	1
PVC Straight Reducer 2" Female to 3/4" Female	1
2" PVC Cap	2
Inline Tee Adapter 2" Socket X 2 NPT	1
4-40 3/16" Nylon Spacer	2
Non-Hardening Thread Sealant	To be applied to pipe threads of adapter socket
Pressure Sensor Connector 4-pin Microfit	1
Battery Connector 2-pin Microfit	1
Connector Contacts	6
Mounting Plate (1/8" 5052 Aluminum Stock Laser Cut	1
m2.5 X 5mm Nylon Hex Standoff	2
m2.5 Nylon Hex Nut	2
m2.5 X 5mm Nylon Screw	2
4-40 x 1/2" Nylon Screw	2
Oatey Clear PVC Primer	1
Oatey Clear PVC Cement	1
Internal Retaining Ring for 14mm I.D.	1
Sintered Stainless Steel Filter-10 Micron	1
Pressure Sensor Housing	1	See design file-housing should be printed using plastic with low water absorption
Miniature Altimeter Module	1
Pressure Sensor Breakout PCB (see separate list under Carrier PCB and Pressure Components)	1
3/4" Schedule 40 PVC Pipe (cut to 24")	1
Devcon 2-TON Epoxy	1
Chemplex 710 Silicon Compound	1
3M Scotch-Weld Acrylic Adhesive	1
O-Ring Silicon Grease (O-Lube for silicon rings)	1
Heat Shrink	1 roll
Coaxial Cable	1

Carrier PCB and Pressure Components List

Name	Amount Required	Picture
Miniature Altimeter and Diving Module	1
Diode Schottky 15V 1A Powermite	1
TVS Diode 3.3VWM 10.3VC DO214AA	1 (note that this part provides over-voltage protection but can be left off if desired)
0.1 uF Ceramic Capacitor	1
RES SMD 2K OHM 1% 1/4W 0603	2
12C Clock Line, 22 Ga White	1
12C Data Line, 22 Ga Gray	1
Ground, 22 Ga Black	1
3.3VDC, 22 Ga Red	1
10uF CER CAP 0805	1
0.1 uF CER CAP 0805	1
10k OHM Resistor 0805	1
470k OHM Resistor 0805	1
1M OHM Resistor 0603	1
N-CH MOSFET 60V SOT23	1
MOSFET BVDSS: 8V-24V SOT23	1
Right Angle 2POS Header	1
JST SH 4-Pin R/A Connector	1
Right Angle 4POS Header	1
Stemma QT QWIIC JST	1
Sockets for Artemis and Bluefruit Modules	2
Pins from Artemis and Bluefruit Sockets	Will cut off sockets in assembly
Microsd Card	1

Equipment List

Ratcheting PVC cutter
Measuring tool
X-acto knife
Voltmeter
Soldering iron
Solder Sucker
DuPont Connector Crimper
Screwdriver
Wire stripper
Extractor Tool
Snap Ring Pliers
Large File
Deburring Tool

Initial Steps

The first step before proceeding should be to 3D print the required sensor housings and retaining blocks, as seen above in the equipment list.
Please read the entire pressure logger construction section before proceeding.

At various locations in the wiki, there will be sections where you will need to test various sensor components before proceeding. Additionally, there are known sensor difficulties that should be accounted for. Those instructions and notes can be found at Testing Steps and Known Issues

PVC Housing

Starting with the top part of the pressure logger, clean the following pieces with a degreaser:
- 2” PVC Cap (2)
- Inline Tee Adapter 2" Socket x 2 NPT
- Note: once items have been cleaned, do not push in the end caps as they will become stuck in the adapter
Construct the PVC Cap with the vent and plug:
- Drill a 10.2mm through hole in the PVC cap
- Insert and glue in the vent and plug with the blue cap facing outwards
- Use the 2 ton epoxy to glue the vent on top of the PVC cap
- Use the O-Lube to install the silicon rings on the Blue Robotics Vent and Plug

Vent and Plug orientation on PVC Cap

Attach both 2" PVC Caps to the Inline Tee 2" Adapter Socket x 2 NPT
- Note: when attaching any of the PVC parts together, use the PVC primer first followed by the PVC cement around whichever regions of each PVC part will be touching each other.
- Gently insert a PVC cap into the adapter to determine which end is less tight around the end cap
- Attach the PVC cap with the vent and plug into the end of the adapter that is tighter by pushing the end cap in while twisting slightly. The top of the end cap should be flush with the edge of the adapter.
- Attach the PVC cap with the without the vent and plug to the less tight end of the adapter.

Inline Tee Adapter with PVC Caps

Next, start construction on PVC for battery holder and carrier board by cleaning the following parts with a degreaser:
- 2" Schedule 40 Adapter Socket x 2 NPT Male
- 2" Schedule 40 PVC Pipe (cut to 9.5" using PVC cutter)
Also will need the stainless steel mounting ring, 3M Scotch-Weld Acrylic Adhesive, and a long Q-tip.
Take the 2" Schedule 40 Adapter Socket x 2 NPT Male and rest it so the pipe threads are facing downwards.
Using a long Q-tip, gently apply the 3M Acrylic Adhesive to the inner edge of the adapter socket.
Gently attach the stainless steel mounting ring to the inner edge of the adapter socket.

Mounting ring inside adapter socket

Attach the adapter socket to the cut 2" Schedule 40 PVC Pipe with the threaded end of the adapter socket facing away from the PVC pipe

Adapter socket to PVC pipe

Then, prepare for construction on PVC for the pressure logger:
Clean the following with degreaser:
- 3/4" Schedule 40 PVC Pipe (cut to 24")
- PVC Straight Reducer 2" Female to 3/4" Female
All major segments of the PVC housing should not be glued together until the carrier board, battery housing, and pressure logger are ready to be installed in the housing. Before continuing with PVC assembly, the carrier board, battery housing, and pressure logger should be constructed.
Prior to screwing the carrier board into the mounting ring, ensure all proper connector pins have been put into place.

Before continuing PVC assembly, the connector from the pressure logger should have been threaded first through the PVC straight reducer 2" female to ¾" female and then the 24" Schedule 40 PVC pipe
Using a 6-32 x 2 1/4" pan head screw, screw the pan head screw into the retaining block on the bottom of the mounting plate and through the stainless steel mounting ring.

Orientation of carrier board in PVC and retaining block hole

The hole in the grey block mounted beneath the carrier board shown in the photo above is where the 6-32 x 24 1/4" pan head screw should be screwed in.

Next, prepare to assemble to pressure sensor stack and attach to 3/4" Schedule 40 PVC Pipe

See section Pressure Sensor Assembly before verifying that the following steps have been completed properly.

Ensure that the pressure sensor has been appropriately attached to the pressure sensor breakout PCB

Reminder: the orientation of the wiring in the Microfit 4 pin is as follows: With the groove oriented upward, the grey wiring goes into the top left hole, the white in the top right hole, the red in the bottom left hole, and the black in the bottom right role. Always ensure the wiring is oriented in the correct way prior to potting the sensor. It is also critical to make sure the pressure sensor is reading accurate data before gluing into place.

Place the sensor into the 3D printed pressure sensor housing, and use the 3M Scotch-Weld Acrylic Adhesive to position the pressure sensor in the housing
Place a small amount of the Chemplex 710 Silicon Compound between the pressure sensor and the sintered filter. Be careful not to put too much of the Chemplex compound or there could be static pressure on the sensor. This might lead to incorrect readings. If too much Chemplex is applied, take the wood end of the long cotton swabs and remove some of the excess Chemplex.
Note: Do not touch the white gel in the sensor.
Apply the sintered filter to the inside of the pressure sensor housing, leaving a small gap between the filter and the applied Chemplex.
Install the snap ring on top of the filter using the snap ring pliers.
Pot the pressure sensor and breakout PCB from the back side of the housing using the 2-TON Structural Epoxy.

Before proceeding, apply the induction interference fix (see above). Then pot the sensor housing into the housing itself. Also read section below on 12C Signal Crosstalk Fix.

Epoxy potting in back side of the pressure sensor housing

Thread the wiring from the bottom of the pressure sensor breakout PCB through the clean 3/4" Schedule 40 PVC Pipe so the pressure sensor connector 4-pin microfit is hanging out of one end and the pressure sensor housing is outside the other end.
As stated above, the wiring should also be threaded through the PVC straight reducer 2" female to 3/4" female. Complete this step if you have not already done so.
Using the 3M Scotch-Weld Acrylic Adhesive, glue the assembled pressure sensor stack to the end of 3/4" PVC pipe.

Pressure sensor housing in PVC and orientation of filter and snap ring

Once the assembled pressure sensor stack has been glued into 3/4" Schedule 40 PVC, prepare to glue the 9.5" schedule 40 PVC to the inline tee adapter, and the 24" schedule 40 PVC to the 9.5" schedule 40 PVC.

Ensure that the carrier board has been screwed into the retaining block and into the mounting ring within the 9.5" PVC, and gather the assembled inline tee adapter, PVC primer, and PVC cement. Using the primer, coat the outside of the PVC threading on the PVC with the carrier board inside as well as the inside of the inline adapter tee end without the PVC caps. After the primer has been applied, apply the cement in the same way the primer was applied.
Apply non-hardening thread sealant for plastics to the pipe threads to ensure a proper seal.
Push and slightly twist the 9.5" PVC into the inline adapter until both PVC parts are secured together.
Then, using a shop towel and degreaser, clean the PVC straight reducer 2" female to ¾" female.
Using the PVC primer and cement, glue the PVC straight reducer to the end of the 9.5" PVC segment.
After attaching the PVC straight reducer, use the primer and cement to attach the 24" Schedule 40 PVC to the other end of the PVC straight reducer.

PVC Housing Assembly

Once assembled, vacuum test the housings. See deployment notes at end of wiki.

All PVC elements should be connected into one singular pressure sensor housing and the unit should now be ready for deployment.

After the housings have been tested, move onto completing the incomplete innards sets. Once these are complete, assign them to a sensor housing and label accordingly. To do this, put an SD card into every OLA with the correct settings (see instructions below on setting up the OLA). At this point, also troubleshoot any electronics that have not passed previous testing.

Building Electronics Carrier

The version 2 design uses the Open Log Artemis (OLA) board along with the Bluetooth Low Energy (BLE) attached to the Proteus carrier board. When working with electronic boards, make sure you are ground and handle all electronics on a static mat. Also, use caution when removing OLA and BLE boards as there is a potential to bend the pins holding the boards in place.

Carrier Board Assembly

First, gather the following parts:

10uF Ceramic Capacitor 0805
.1uf CER CAP
10k OHM Resistor 0805
470k OHM Resistor 0805
1M OHM Resistor 0603
N-CH MOSFET 60V SOT23
MOSFET BVDSS: 8V-24V SOT23
Right angle 2POS Header
JST SH 4-Pin R/A Connector
Right Angle 4POS Header

First, solder the initial parts on the Proteus printed carrier board in the following order:

10uF CER CAP 0805 to the connection pads marked C1.
0.1 CER CAP 0805 to connection pads marked C2.
10k OHM Resistor 0805 to connection pads marked R2.
470k OHM Resistor 0805 to connection pads marked R3.
1M OHM Resistor 0603 to connection pads marked R4.
N-CH MOSFET 60V SOT23 to connection pads marked Q1.
MOSFET BVDSS: 8V-24V SOT23 to connection pads marked Q2.
Right Angle 2POS Header to the connection marked J1.
Right Angle 4POS Header to the connection marked J3.
JST SH 4-Pin R/A Connector to connection marked J2.
- Note: Connections between each pad must be kept separate. It may be useful to do one corner connection first, and then place the 4-Pin connector onto that connection. Once the connector has been attached to one pad, it may be easier to then solder the remaining corner connections and gently push the 4-Pin Connector into place. Once the connector has been fully soldered into place, solder the remaining connections, while being careful to avoid joining connections.

Top of Carrier Board

Once the top of the carrier board has been soldered, flip the Proteus PCB over and create a jumper connection on the pads marked Jumper2.
Also must solder the bottom of the J1 and J3 pins, which are visible on the backside of the board.

Note: It is important to wash the carrier board after soldering with isopropyl alcohol and a toothbrush to clear excess rosin.

Bottom of Carrier Board

Flip the board back over.

Take two of the sockets for the Artemis and Bluefruit Modules.

Take one of the sockets, and place the pins in the 8 vertical holes under the U1 labeling and then place the other socket in the 8 vertical pin holes under the U2 labeling. The black segment of the socket should be exposed above the top of the PCB and the sharp end of the pins should be exposed on the bottom side of the PCB.

Once all sockets are pushed into place, flip the board over and solder each socket into the board.

Note: When soldering the vertical pins into place, each connection should form a volcano-shaped dome on the connection pad with the bottom widening toward the base of the pad. The pad should be completely covered by the solder.

Orientation of sockets through bottom of PCB

Once the socket pins have been soldered into place, take a pair of pliers and remove the excess length from each pin so that the PCB can be flush with the tabletop. When removing the excess length off each pin, snip the pins into a shop towel to prevent injury and losing the pins.
Save the length of the pins that have been cut off for soldering to the OLA and BLE.

Next, prepare to attach the BLE and Artemis Boards to the Proteus PCB.

Attaching Artemis and BLE Boards

First, the MEAS Jumper on the OLA board must be cut.

Use an x-acto knife or similar to cut the MEAS jumper on the OLA board (as described in the "Vin Pin" section in SparkFun's OLA Overview). Before powering on the pressure logger, either by battery or via computer, make sure you read the Pressure Logger Precautions. Since we are cutting the MEAS Jumper, you must be careful powering the OLA so that you don't fry the board.
Use a voltmeter on Ohm setting to check resistance between the 2 connected pins – before cut, it should be 0 (no resistance), after the cut you should see a large reading (e.g., mega-ohm order of magnitude).

Where to cut MEAS jumper

Once the OLA board has been cut, prepare to attach the OLA and BLE to the PCB.

Next, orient the board so that the labeling U1 and U2 are toward the top of the PCB and POUT1 and QOUT1 are toward the bottom.

Take the pins that have been cut off and insert 8 pins into each of the exposed socket holes. The narrower end of the pin should go into the socket.

Slide the OLA board onto the line of pins to the left of the labeling U1 and POUT1.

The pins should slide through the vertical line of holes to the right of the MEAS label on the OLA Board. Additionally, the holes in the corners of the OLA board should line up with the holes on the PCB.

Then, with the board still oriented the same way, slide the BLE board onto the remaining line of pins under the labeling U2. The pins should go through the vertical line of holes in the BLE board.

Like the OLA board, the holes in the right side of the BLE board should line up with holes in the PCB once the BLE has been put into place.

Similar to how the pins were soldered on the bottom of the PCB, solder the pins to the top of the OLA and BLE.

Using the pliers, cut off the end of the pins so that only the part that was soldered into place remains. Remember solder first and cut second.

PCB with OLA and BLE boards attached

Once the BLE and OLA Boards have been attached to the PCB, take a large file and file down the sides of the carrier board so that each side is smooth. It is important to be careful when filing to avoid injury from loose fiberglass.

Next, prepare to solder a jumper cable starting from the POUTSM connection to fit into the PIN1 connection.

Taking a small part of the black ground wiring, cut a small segment of wire to connect the holes labeled POUTSW and PIN1. Ensure that both ends of the cable have been stripped, exposing a small length of wire.

Insert the wiring from the top of the PCB so that the exposed end of the wiring is barely poking through the bottom of the board. Solder the bottom of the exposed wire on the bottom of the carrier board so that the wire is held into place and the connection is stable.

May be easier to insert one wire end at a time and solder one end into place before moving onto the other wire end.

Soldering Wire Jumper into PCB

Orientation of Wire Jumper in PCB

Finally, take the Stemma QT QWIIC JST cable. Push one end of the cable into the 4-pin connector soldered into the J2 connection on the PCB and push the other end into the QWIIC connector on the OLA board.

After this step, gather the following items to stabilize the Pi stack prior to installing the Pi on the mounting plate:

4-40 x 3/16" Nylon Screws (3)
4-40 Nylon Insert Lock Nuts (3)
4-40 x ½ Nylon Screw (2)
4-40 x 3/16" Nylon Spacer (2)
4-40 Nylon Hex Nut (5)
M2.5 x 5mm Nylon Screw (2)
M2.5 x 5mm Nylon Hex Standoff (2)
M2.5 Nylon Hex Nut (2)

Start by setting the 4-40 nylon insert lock nuts, 4-40 x 3/16" nylon screws, and 3 of the 4-40 nylon hex nuts aside for now. These will be used later to further secure the PCB to the mounting plate.

First, stabilize the BLE board:

Take the m2.5 x 5mm nylon hex standoffs and place them through the 2 holes in the end of the BLE board that align with the 2 holes in the rightmost side of the PCB board. The wider end of the standoffs should be beneath the BLE board and the skinnier end should be exposed above the BLE board.
Take the m2.5 nylon hex nuts and twist them onto the top of the standoffs until the hex nuts are flush with the BLE board and the standoffs are held into place.
Take the m2.5 x 5mm nylon screws and screw them into the bottom of the standoffs, completely securing the BLE to the carrier board

Next, stabilize the OLA board:

4-40 x 3/16" nylon spacers and align them beneath the two leftmost holes in the OLA board that also align with the carrier board. The spacers should be in between the OLA board and the carrier board.
Take the 4-40 x ½ nylon screws and screw them through the bottom of the PCB and through the spacer so that the threads of the screws are exposed above the OLA board.
Take the 2 remaining 4-40 nylon hex nuts and screw them onto the threads of the exposed screws until the hex nuts are flush to the OLA board. The OLA board should now be completely secured to the PCB.

Top View of PCB Stack

Side View of PCB Stack

The BLE and OLA Boards should now be completely secured to the Proteus Carrier Board and ready to be mounted to the mounting plate.

Electronics Carrier and Mounting Plate Assembly

Gather the following items:

M2.5 x 5mm Nylon Hex Standoff (3)
4-40 x 3/16" Nylon Screws (3)
4-40 x 7/16" Pan Head Screws (4)
The remaining 4-40 Nylon Hex Nuts (3)
The remaining 4-40 Insert Lock Nuts (10)
4-40 x 3/8" Flat Head Screws (4)
4-40 x ½" Pan Head Screws (2)
Mounting Plate
Battery Holder
Lower Guide Ring
Retaining Block
Heat Shrink

Prior to beginning mounting plate assembly, the battery holder wiring needs to be prepared:

Take the spools of red and black wiring and cut off a length of approximately 12-13 inches of the black wire and 2.5-3 inches for the red wiring.
Take the 2 connector contacts and crimp one end of each type of wiring into a connector contact. One end of each wire should still have exposed wiring and the other end of each wire should have a contact attached.
Take the red wiring and solder the end with the exposed wiring to the connection on the front of the battery holder (positive end). Once the wiring has been soldered to the battery holder, apply heat shrink to the solder around the connection and the wiring so that the solder is completely covered by the heat shrink.
Take the black wiring and solder the end with the exposed wiring to the connection on the back of the battery holder (the end with the spring). Once the wiring has been soldered to the battery holder, apply heat shrink around the soldered connection and wiring.
Take the battery connector 2-pin microfit. Insert the connector crimped to the black wiring in the top slot in the microfit and the red wire connector in the bottom slot.

Then, begin mounting plate assembly.

First, attach the lower guide ring to the mounting plate:

Take the mounting plate, 2 of the 4-40 x ½" pan head screws, the lower guide ring, and 2 of the 4-40 nylon hex nuts. Orient the mounting plate so that it is horizontal on the table. Place the lower guide ring on top of the end of the mounting plate so that the two holes in the guide ring are aligned with the two holes on the edge of the mounting plate. The flat edge of the mounting plate should be flush with the mounting plate.

Holding the lower guide ring in place on the mounting plate, screw in the pan head screws through the bottom of the mounting plate so that the threads of the screws are exposed above the edge of the lower guide ring. Once the screws have been inserted, screw the nylon hex nuts onto the ends of the pan head screw threads.

Next, attach the battery holder and retaining block to the mounting plate:

Take the mounting plate with the lower guide ring attached, 4 of the 4-40 3/8" Flat Head Screws, 4 of the 4-40 x 7/16" pan head screws, 8 of the 4-40 nylon insert lock nuts, and the retaining block. Place the battery holder on top of the mounting plate so that the end with the spring is oriented toward the lower guide ring, the 4 holes in the bottom of the battery holder are aligned with the 4 holes in the mounting plate, and the positively labeled end of the battery holder is oriented horizontally toward the other end of the mounting plate. If the holes are not in the bottom of the mounting plate or battery pack the holes might need to be manually drilled in. To do this, use a drill bit matching the 4-40 flat head screws and 4-40 pan head screws.

Holding the battery holder in place on the mounting plate, insert the 4 flat head screws into the top of the battery holder so that the screw head is flush to the bottom of the battery holder. The screw threads should be exposed under the mounting plate. Take 4 of the insert lock nuts and screw them onto the exposed threads, securing the battery holder into place.

Then, take the retaining block and align it under the 4 holes in the center of the portion of the mounting plate that is still exposed. Holding the retaining block in place under the mounting plate, screw the pan head screws into the top of the mounting plate so that the screw heads are flush to the mounting plate and the threads are exposed under the retaining block. Once the screws are in place, screw the insert lock nuts onto the ends of the thread to secure the retaining block to the bottom of the mounting plate.

Side View of Mounting Plate

Top View of Mounting Plate

Finally, secure the carrier board to the assembled mounting plate:

Take the M2.5 x 5mm Nylon Hex Standoff (3), the remaining 4-40 Nylon Hex Nuts, the 4-40 x 3/16" pan head screws, and the assembled PCB stack. Take the nylon hex standoffs and insert them into the 3 remaining empty holes in the uncovered end of the mounting plate. The wider end of the standoffs should be flush to the top of the mounting plate with the skinner end exposed below. Once the standoffs have been put into place, screw the 4-40 nylon hex nuts onto the skinny end of the standoffs, securing the standoffs to the mounting plate.

Then, align the holes in the end of the PCB stack near the OLA board and the one in the middle of the PCB stack with the holes in the top of the standoffs. The PCB stack will be installed next to the battery holder. Take the pan head screws and screw them through the PCB stack into the standoffs so that the screw heads are flush with the carrier board. The PCB stack should now be secured to the mounting plate.

Fully Assembled Mounting Plate

Note: images in this section have been compressed and are not true to size.

Testing the OLA Board

Once the Mounting Plate and Battery Pack have been assembled, it is necessary to test the OLA board to ensure that it is working correctly. The OLA must be tested before the PCB stack is sealed into the PVC.

First, put batteries into the battery carrier. Then, connect the sensor to the battery carrier by plugging the connector from the battery pack into the Pressure Carrier Board. Next, plug in the USB-C and connect the OLA to an open terminal system.

If the OLA powers on, double-check that the jumper on the OLA has been removed. If not, re-cut the jumper between MEAS on the OLA.
If the OLA does not power on, you are good to continue on.

Plug the batteries properly into the battery carrier. Using PuTTY or another terminal system, change the fluid density and conversion factor within the sensor settings. If the sensor settings are not updated, the sensor will not measure anything.

Pressure Sensor Assembly

Pressure Sensor Wiring

Gather the following items first:

White wiring
Grey wiring
Black wiring
Red wiring
Pressure sensor connector 4-pin microfit (1)
Connector contacts (microfit) (4)

Taking each spool of wire, use the wire stripper to strip the ends of each wire. The amount of wire exposed should be just enough so that the first "wings" on the connector contacts are on the wiring and the second set is on the wire's Teflon. So, a very short length of wiring should be exposed.

Then, cut each wire off of the spool to a length of approximately 37". The length will vary to fit the length of the ¾" PVC pipe used for each individual sensor. Once each wire has been cut off the spool, prepare to crimp on the contacts.

Using the connector crimper, crimp each wire end into the smaller size of the connector contacts. Once each wire end has a connector contact, insert the contacts into the connector 4-pin microfit. With the groove in the 4-pin microfit facing upward, insert the grey wire contact into the top left of the microfit, the white wire connector in the top right of the microfit, and red wire connector in the bottom left hole of the microfit, and the black wire connector in the bottom right corner hole of the microfit.

After the wiring has been inserted into a connector, take the ends of the red and black wires (the end with the exposed wiring) and insert them into the drill where the drill bit would normally go. The drill can then be used to twist the wiring together before being soldered to the pressure logger board. Note that the white and grey wires should remain untwisted.

See the epoxy potting photo above for an example of correct wiring (note that the white and grey wires are not typically twisted).

12C Signal Crosstalk Fix

Gather the coaxial cable.
Cut the grey and white wires with a couple of inches remaining and splice on the coaxial cable using the center conductor. Trim off the shield neatly.
At the other end of the coaxial cable, crimp on the sockets that go in the connector and leave those shields exposed for later access.

Then, remove the old grey and white wires from the connector and insert the coaxial cable into the appropriate spots. Clip the ground wire so the two shields and the two clipped ends of the ground wire can be connected together. Place heat shrink on the wire before soldering and testing.

Tidy up the connections using the heat shrink positioned on the wire before soldering and final testing.

Applied 12C Signal Crosstalk Fix

Pressure Sensor Soldering

Gather the following items:

Miniature Altimeter and Diving Module (pressure/temperature sensor). The white center of the module should not be touched to avoid pressure discrepancies
Diode SCHOTTKY 15V 1A Powermite, which provides reverse polarity protection.
0.1 uF ceramic capacitor, which is required and could be increased up to approximately 1uF
RES SMD 2K OHM 1% 1/4W 0603 (2). Note: Pullup may vary due to clock speed and wire length, typically 1k to 10k

Note: The following procedure is the most difficult part of construction if not well practiced.

Prior to soldering these parts on the pressure sensor breakout PCB, the following preparations should be made:

Clean boards before putting module on with brush in isopropyl alcohol bath.
Tin all circuit board pads with small, flat solder. Line up pads with notches on pressure sensors.

General Notes on Soldering and Board Orientation:

The cathode side of diode D2 on the pressure transducer board has a line. The line side goes toward the dot on the circuit board.
Tack one pad pushing down from top with tweezers for pressure, then recheck alignment.
The pads are fixed in place once solder wicks up into gaps.
Check that adjacent pads haven't shorted, and still show high resistance using a voltmeter. Exception: back right two and front middle two holes are wired together, so there should be no resistance between these pads. Check the resistance with really pointy voltmeter probes.
It may be easier to put solder on the end of the iron and then apply the solder to pads which may help with securing parts into place correctly.

Process for soldering on pressure sensor breakout PCB pieces:

Use Rosin core solder and rosin flux pen as needed to solder on the following pieces.

Solder Diode Schottky 15V 1A Powermite to connection pad labeled D1.
Solder .1uF Ceramic Capacitor to connection pad labeled C1.
Solder 1 RES SMD 2K OHM 1% 1/4W 0603 to connection pad labeled R1
Solder 1 RES SMD 2K OHM 1% 1/4W 0603 to connection pad labeled R2
Solder Miniature Altimeter and Diving Module to connection pad labeled U1.

Completed Pressure Sensor Soldering

Install wiring using PTFE, 22 or 24 AWG wire, stranded. Select the wire length appropriate for the planned probe length.

The white wiring should be soldered into the position marked CLK.
The gray wiring should be soldered into the position marked SDA.
The black wiring should be soldered into the position marked G1.
The red wiring should be soldered into the position marked VCC1.

Soldering wires into place

Clean the board with 100% Isopropyl alcohol and swabs. Reminder: Do not touch the white silicon gel on the pressure sensor
After cleaning, handle the board with gloves to minimize oil from hands.
Test the sensor to validate it is operational and provides reasonable data before you move on to the gluing operations.
Prep and clean plastic printed sensor housing using 100% Isopropyl alcohol and handle the housing with gloves after cleaning.
Clamp wires with a bench vise about 1" below the PCB so the pressure sensor is pointing straight up. Place the cleaned sensor housing over the PCB so the stainless rim on the pressure sensor sits centered in the housing hole. We recommend doing 2 sensor housing glue operations at a time since the glue dries fairly quickly.
Cut a wooden Q-tip on an angle to use as a pointed glue applicator.
Mix a small amount of 3M 8425 acrylic adhesive on a small piece of cardboard or other clean material.
Lift the housing up and apply glue on top of the PCB and around the stainless sensor body. Carefully reseat the housing.
Using the sharp Q-tip, apply glue to the gap between the sensor and plastic housing. Be careful to not touch the silicon gel of the sensor. Work around the entire circumference of the sensor. Ideally, the glue will provide the water-tight seal at this point in the assembly process.
Allow the glue to dry for at least 1 hour.
Remove the sensors from the clamp after about an hour. Turn the sensor face down and use the clamp to suspend the long wires so the sensor housing face is flat on the bench surface.
Use blue painter's tape to protect the sensor housing face and sides. Now glue and get on the sensor housing sides or down into the sensor cavity.
Mix the 2-ton epoxy and use a syringe or suction tube to suction glue into the applicator and the expel the glue into the rear cavity of the sensor housing. Fill the cavity up to about .2" of the back top. Move the wires around gently to reduce any air cavities. Let dry for the 24 hours.
Cut ¾" PVC to length. Clean up the edges with a deburring tool.
With gloves on, clean the tube with the degreaser and then 100% Isopropyl alcohol. The degreaser will also remove PVC writing which makes it look better. Make sure to clean the inside of the PVC tubing.
Remove the protective tape from the sensor housing after the glue has dried. Put a fresh piece of painter's tape over the face of the housing to protect the sensor face.
Perform a test fit of the sensor housing into the PVC tube. PVC tubes have enough variation to cause fitting issues. The sensor housing cannot be too loose or too tight. If too loose there may be gaps in the glue layer causing leaks. If too tight, the glue will be wiped off on insertion causing gaps and leaks. Preferably the outer diameter of the sensor housing should be between .01"- .02" smaller than the inside diameter of the PVC pipe.
Perform another sensor test and then feed the wires down the PVC pipe. Apply glue to the sensor housing into the PVC tube with the 3M DP8425 Adhesive. Apply a thin coat of the glue around the sensor housing and under the sensor flange as well as on the inside of the ¾" PVC pipe (after the wire is put in the pipe so glue does not get on the connector). Insert the sensor housing inot hte PVC. Glue should fill any void between the sensor housing flange and the cut edge of the PVC. Clean off any excess.
Make sure to completely coat. Allow the glue to dry for 1-2 hours.
Test and ready for assembly with the deployment housing electronics.

Final Pressure Logger Assembly

Ensuring PVC is fully waterproofed

Attach one end of a vacuum to the end of the PVC cap with the vent plug in it. Use the vacuum to remove 10 psi from the pressure transducer. Leave the pressure transducer for 10 minutes, and then check the pressure reading again.

If the pressure has remained steady with the -10 psi reading, the pressure transducer is properly sealed and air-tight.

To ensure the PVC is waterproof, dip the pressure transducer into a bucket of water and push air through using the vacuum pump. No air bubbles should be visible. Also, check for water drips on the inside of the casing.

The final step prior to deployment should be to calibrate the sensors and assign them a pressure transducer number and record their offset values. Please see section on calibration under pressure logger setup.

Testing Steps

Testing Check 1

The first testing check is to check the recognition of the sensor itself. This should be done after the sensor is potted into the sensor housing. This test is completed using a completed sensor with a PCB that is known to be working, with an OLA and Bluetooth board attached.

First, take an unknown sensor and plug it into the computer.
Go under menu 6 in the terminal, and check to see that option 1 is registering MS5803 (the pressure sensor).
If this option is shown, the PCB is recognized.

The next check is to see if there are reasonable pressure values being recorded.

These should also be visible under menu 6, and should be in the low 1000s in mbar.

Testing Check 2

Once sealed, the pressure logger should be vacuum tested. Attach one end of a vacuum to the end of the PVC cap with the vent plug in it. Use the vacuum to remove 10 psi from the pressure transducer. Leave the pressure transducer for 10 minutes, and then check the pressure reading again.

If the pressure has remained steady with the -10 psi reading, the pressure transducer is properly sealed and air-tight.

During this test, the whole sensor should be submerged.