Learn how to assemble a sensor node with a depth sensor for deployment in the field! This guide walks through solar panel setup, wiring, sensor connection, and enclosure assembly adapted on the open-source work from https://www.digitalwaterlab.org/build.
Place each ferrule one at a time into the crimping tool. Squeeze the handles firmly to crimp it. The ferrule should be tight and should not slip off if pulled gently
Optionally, label the red and black wires so it’s easy to connect them to the correct terminals later
Connect the barrel connector end of the solar panel to the female end of the solar panel extension cord
Step 3: Install the Solar Panel Wire
Gather materials:
2-pin screw terminal
Cable gland
Flathead screwdriver
Disassemble the cable gland:
Locate the pre-drilled hole on the bottom left of your enclosure meant for the solar panel wire
Identify the parts of the cable gland:
The cap (screws down to tighten the seal)
The rubber grommet (squeezes the cable)
The main body with threads (goes through the wall of the box)
The locknut (secures the gland inside the box)
Install the cable gland:
From the outside of the enclosure, insert the threaded body of the cable gland through the pre-drilled hole
On the inside of the enclosure, screw on the plastic locknut to secure the gland in place. Hand-tighten until snug
Now take the solar panel extension wire and:
Slide the cap over the wire
Feed the wire through the installed gland body and into the enclosure
Once the wire is positioned, push the grommet into place inside the cap, and screw the cap onto the gland body. This compresses the grommet and creates a tight seal around the cable
Check that the wire is secure and doesn’t wiggle or slide. Gently tug to test. The opening should now be watertight
Connect the ferrules to the terminal block:
Grab a 2-pin screw terminal block
Loosen the terminal screws slightly using a small flathead screwdriver. Do not remove them completely, just open them enough to insert the wires
Insert the red wire ferrule into the left terminal and the black wire ferrule into the right terminal
Hold the wire steady and tighten the screw down firmly. The ferrule should not move or pull out when gently tugged
Step 4: Attach the solar panel to the enclosure
Gather materials:
Mounting nuts (4 pieces)
Mounting screws (4 pieces)
Plyers
Phillips screwdriver
Attach the solar panel to the enclosure:
Set the enclosure lid face-up on a flat surface, with the sensor and cable gland holes facing toward you
Place the sheet metal on top of the lid so the long side of the bracket is aligned with the sensor/cable side of the box
Line up the 4 pre-drilled holes in the bracket with the mounting holes in the enclosure lid
Insert a screw through each hole from the inside of the bracket, going down into the lid
On the outside of the lid, place a mounting nut on each screw
Tighten each screw securely using a screwdriver on the inside and pliers outside
Step 5: Prepare the depth sensor
Gather materials:
5-pin screw terminal
Depth sensor
Flathead screwdriver
Wires (1 each of red, black and white)
Wire the depth sensor:
Cut x inches of red, black, and white wires
Use wire strippers to remove about 1/4 inch of insulation from both ends of the wires
Locate the pre-attached screw terminal on the back of the sensor
Insert one end of the wires into the terminal:
White → Data
Red → Power
Black → Ground
Tighten the terminal screws with a flathead screwdriver to secure each wire. Tug gently on each one to confirm the connection is snug
Connect the other end of the wires into the 5-pin screw terminal
Step 6: Attach the depth sensor
Gather materials
Depth sensor
Depth sensor mounting hardware
Attach the rubber ring to the threaded portion of the depth sensor
Insert the sensor stem through the large hole in the enclosure lid from the outside
On the inside of the lid, install the mounting hardware:
Screw on the hex nut until the sensor is secure
Step 7: Prepare and insert the battery
Gather materials:
2-pin terminal block
Battery
Extra large zip ties (2 pieces)
Ferrules (2 pieces, sized for 20 AWG stranded wire)
Ferrule crimping tool
Flathead screwdriver
Non-conductive battery foam
Scissors
Side cutters
Prepare the battery connection:
Slide a ferrule over each wire end, ensuring that all the copper strands are fully inserted into the metal tube
Place each ferrule one at a time into the crimping tool. Squeeze the handles firmly to crimp it. The ferrule should be tight and should not slip off if pulled gently
Connect the ferrules to the terminal block:
Grab a 2-pin screw terminal block
Loosen the terminal screws slightly using a small flathead screwdriver. Do not remove them completely, just open them enough to insert the wires
Insert the red wire ferrule into the left terminal and the black wire ferrule into the right terminal
Hold the wire steady and tighten the screw down firmly. The ferrule should not move or pull out when gently tugged
Insulate the battery:
Cut a piece of battery foam to fit around the battery
Place the battery between the foam layers, with one piece below and one above, creating a protective buffer on both sides.
Loop the zip ties around the foam-wrapped battery and pull them tight enough to hold it securely, but not so tight that it compresses the battery or distorts the foam
Step 8. Check the microcontroller board’s solar charge potentiometer
Gather materials:
2-pin screw terminal
Battery
Enclosure
Flathead screwdriver
Jumpers (6)
Laptop
Microcontroller board
Multimeter
USB voltage converter and power supply
Wires (red and black)
Attach 6 jumpersto the microcontrollerin the spots shown
Prepare the USB voltage converter and power supplywire
Cut one red and one black wire, long enough to reach your microcontroller
Strip about 1/4 inch of insulation from both ends of each wire
Insert the red wire into the positive terminal and the black wire into the negative terminal
Use a multimeter to check for 5.9V between the red and black wires. You may have to set the USB voltage converter and power supply to 5.8V for the multimeter to read 5.9V
Grab a 2-pin screw terminal block
Loosen the terminal screws slightly using a small flathead screwdriver. Do not remove them completely, just open them enough to insert the wires
Insert the red wire into the left terminal and the black wire into the right terminal
Hold the wire steady and tighten the screw down firmly. The wire should not move or pull out when gently tugged
Plug in the USB voltage converter and power supply’s terminal block into the bottom left terminal labeled X1 on the microcontroller board
Connect a partially discharged battery into the bottom right terminal labeled X11 on the microcontroller board
This calibration step won’t work properly with a fully charged battery. If the battery is charged, the LED may not respond
Adjust the charge potentiometer
Locate the silver potentiometer next to the charge controller chip
Using a small flathead screwdriver, turn the screw slowly
The center hole is shallow and can strip so it’s best to use a small flathead screwdriver instead of a Phillips
Turn clockwise until the charge LED turns on
If the charge LED is already on when you first connect the USB power supply:
Slowly turn the potentiometer counterclockwise until the charge LED turns off
Then, turn it clockwise slowly until the LED just begins to turn on.
The LED indicates that the solar charge voltage is high enough to begin charging the battery
Unplug the USB voltage converter and power supply
Unplug the batteryand charge it
Step 9. Prepare the microcontroller board
Gather materials:
Cellular antenna
Cellular module
Enclosure
GNSS antenna
Microcontroller board
MicroSD Card
SIM Card
Insert SIM card into the bottom of modem
Attach the GNSS to the bottom modem
Connect the GNSS to the small gold connector on the cellular modem labeled
Push straight down until you feel it snap in. Do not twist
Place the rough-sided Velcro strip to the back of the GNSS
Attach the antenna to the top modem
Connect the antenna to the small gold connector on the cellular modem labeled X1
Push straight down until you feel it snap in. Do not twist
Place the rough-sided Velcro strip to the back of the antenna
Attach the modemto the microcontroller
Align the modem’s pins with the header on the microcontroller
The antenna pin will be facing the top side of the board and the GNSS will be facing the right side
Press gently but firmly to seat it fully
Insert the microSD card into the microcontroller
Step 10. Insert the microcontroller board
Gather materials:
Phillips screws (6)
Phillips screwdriver
Place the battery inside the enclosure with the wire facing the bottom-side of the enclosure
Place the microcontroller inside the enclosure and secure the microcontroller with 4 Phillips screws
The modem should be facing the top of the enclosure
Connect the battery to the bottom left terminal on the microcontroller:
Take the 2-pin screw terminal carrying power from the battery and plug it into the bottom left terminal labeled X1 on the microcontroller board
Make sure polarity matches the picture
Connect the solar panel to the bottom right terminal on the microcontroller:
Take the 2-pin screw terminal carrying power from the solar panel and plug it into the bottom left terminal labeled X11 on the microcontroller board
Make sure polarity matches the picture
Connect the depth sensor to the microcontroller:
Insert the 5-pin screw terminal from the depth sensor into the matching labeled block on the board
Secure the GNSS and cellular antennato the nearest wall that has a soft-sided Velcro strip:
Secure loose cables:
Gently route wires to reduce clutter and avoid tangles
Step 11: Final Checks
You’ve now completed assembly of the depth sensor node! Before sealing the enclosure, double-check the following:
All screw terminals are fully tightened
No loose wires or exposed copper
Antennas are securely attached
Battery is secure and insulated
MicroSD card is inserted
All components fit neatly inside the enclosure
Congrats! You have built a depth node!Now you can learn how to program it.
