Introduction: IOT123 - ASSIMILATE SENSOR HUB: ICOS10 GENERIC SHELL (HOOKUP WIRE) Assembly

About: The tension between novelty and familiarity...

UPDATE

We recommend you use the IDC circuit (not HOOKUP) for more reliability. This HOOKUP assembly is okay for non mission critical operation if you have time to verify the circuit. I found some wires (top layer of panels: red/yellow) not long enough, and that continuity/isolation tests were needed during and after most assembly processes. The IDC design minimizes the solder points, offers better structure at the headers (sensor contacts) and solves any strain relief problems.

SUMMARY

Slated are several ASSIMILATE SENSOR HUBS. They have a common metadata and sensor dump interface with I2C ASSIMILATE SENSORS. That means a new sensor can be developed, and the MCU that hosts it does not need to be reprogrammed to accommodate the new functionality - just plug it in and reboot. The sensor data will be automatically published to a MQTT server. We expect to develop ASSIMILATE ACTORS support: post a MQTT topic that the HUB listens to, and then routes the message to an actor (relay, indicator etc).

One range of the ASSIMILATE SENSOR HUBS is the ICOS10: a geometry based on the upper 3/4 of the Platonic Solid "Icosohedron", which can host 10 sensors. This separates the individual sensors which can affect one another's readings and provides room for larger compound mashups.

The range is expected to support different MCUs and power arrangements, so the reusable tasks have been split up into separate instructions. The main hardware functions of the HUBs are developed as inch square daughter boards that can be swapped out for enhanced/different functionality.

This article concentrates on the assembly of the outer shell of the housing that has 10 sockets for sensors and a panel for accessing power for the unit. This shell may be useful for other IOT projects.

Step 1: Materials and Tools

    Bill of Materials and Sourcing list.

    1. 3D printed parts (1 set)
    2. 3D printed Header Jig (1)
    3. 3D printed Void Punch (2)
    4. 3P Female Headers (20)
    5. Ø 0.8mm wire (1m)
    6. Hookup wire (~1m)
    7. Female-Female Dupont Jumper Wire
    8. Wire Cutters (1)
    9. Small Pliers (1)
    10. Solder Flux Pen (1)
    11. Solder and Iron (1)
    12. Hot Glue and Gun (1)
    13. Strong Cyanoachrylate Adhesive (1)
    14. 4G x 6mm self tapping countersunk screws (~20)

    Step 2: Assembly

    There are variations on how the circuit can be arranged; this assembly assumes a common connected layout for all sensor sockets. The individual instructables for the variations will cover any changes to the steps covered here.

    PREPARING THE PANELS

    Any changes on the circuit designs will be impacted here. As each panel is joined (steps below), the headers/key are added/glued, the wires are soldered (in and out) and the 3P header pins and wires are hot-gued for strain relief/insulation. PANEL (1) will only have out wires, joining to PANEL (2); the rest have wires in and out.

    Prior to starting any assembly the panel voids can be widened for fit with the VOID PUNCH. On first use, the HEADER JIG may need some fine adjustments with a needle file. Some light vegetable oil (if no intention of painting) may create a release barrier where glue is used.

    50mm 28AWG wire was used on the first 6 panels (1-6) and 100mm wire on the last 4.

    So this process occurs before any joining i.e. on PANEL (1), and after a panel has been joined with a wire hinge.

    1. Place 2 of 3P FEMALE HEADERS down in the HEADER JIG.
    2. Carefully apply adhesive on the long side of the KEY and slide it into position at right angles with a 3P FEMALE HEADER.
    3. On the outside of the added panel, insert the protrusions from the HEADER JIG into the VOIDS on the PANEL.
    4. When flush with inside of panel apply Cyanoachrylate Adhesive in the cracks of the HEADER/KEY/PANEL. Wait to dry.
    5. Bend the pins down in the direction of the out wires. Apply Solder Flux and Tin.
    6. On all but PANEL (1) solder the hookup wires from the previous PANEL (in wires) , onto the pins on the 3P HEADERS (color layouts in diagram above). On the last socket panel, use the DuPont connectors i.e. cut in half with a female connector left to connect to the MCU.
    7. Carefully solder the "out wires" onto the same pins.
    8. Covers HEADER/WIRE joints with hot glue thinking of strain relief as you do it.
    9. Detach panel and headers from HEADER JIG, from the underside by gently pushing the 3P Headers out of the JIG a little of each one alternating.

    JOINING THE PANELS

    When the wires are inserted, they can be cut off flush with outer hinges afterwards.

    1. Take 2 PANEL TYPE 1's, align Side (2) holes on PANEL (1) with Side (1) holes on PANEL (2) and insert wire using pliers/cutters.
    2. Align Side (2) holes on PANEL (2) with Side (1) holes on a new PANEL TYPE 1 "PANEL (3)", and insert wire using pliers/cutters.
    3. Align Side (2) holes on PANEL (3) with Side (1) holes on a new PANEL TYPE 1 "PANEL (4)", and insert wire using pliers/cutters.
    4. Align Side (2) holes on PANEL (4) with Side (1) holes on a new PANEL TYPE 1 "PANEL (5)", and insert wire using pliers/cutters.
    5. Align Side (2) holes on PANEL (5) with Side (1) holes on PANEL (1), and insert wire using pliers/cutters.
    6. Align Side (3) holes on PANEL (1) with Side (1) holes on a new PANEL TYPE 1 "PANEL (6)", and insert wire using pliers/cutters.
    7. Align Side (3) holes on PANEL (2) with Side (1) holes on a new PANEL TYPE 1 "PANEL (7)", and insert wire using pliers/cutters.
    8. Align Side (3) holes on PANEL (3) with Side (1) holes on a new PANEL TYPE 1 "PANEL (8)", and insert wire using pliers/cutters.
    9. Align Side (3) holes on PANEL (4) with Side (1) holes on a new PANEL TYPE 1 "PANEL (9)", and insert wire using pliers/cutters.
    10. Align Side (3) holes on PANEL (5) with Side (1) holes on a new PANEL TYPE 1 "PANEL (10)", and insert wire using pliers/cutters.

      The order of the remaining panels is not important, basically connecting the 2 sides of the later panels...
    11. Align Side (3) holes on PANEL (10) with Side (1) holes on a new PANEL TYPE 2 "PANEL (11)", and insert wire using pliers/cutters.
    12. Align Side (2) holes on PANEL (11) with Side (2) holes on PANEL (6), and insert wire using pliers/cutters.
    13. Align Side (3) holes on PANEL (6) with Side (1) holes on a new PANEL TYPE 2 "PANEL (12)", and insert wire using pliers/cutters.
    14. Align Side (2) holes on PANEL (12) with Side (2) holes on PANEL PANEL (7), and insert wire using pliers/cutters.
    15. Align Side (3) holes on PANEL (7) with Side (1) holes on a new PANEL TYPE 2 "PANEL (13)", and insert wire using pliers/cutters.
    16. Align Side (2) holes on PANEL (13) with Side (2) holes on PANEL PANEL (8), and insert wire using pliers/cutters.
    17. Align Side (3) holes on PANEL (8) with Side (1) holes on a new PANEL TYPE 2 "PANEL (14)", and insert wire using pliers/cutters.
    18. Align Side (2) holes on PANEL (14) with Side (2) holes on PANEL PANEL (9), and insert wire using pliers/cutters.
    19. Align Side (3) holes on PANEL (9) with Side (1) holes on a new PANEL TYPE 3 "PANEL (15)", and insert wire using pliers/cutters.
    20. Align Side (2) holes on PANEL (15) with Side (2) holes on PANEL PANEL (10), and insert wire using pliers/cutters.

    ADDING THE COLLARS

    When the outer shell is complete with triangle panels and 3P Headers/keys, the unit will be stable enough for the collars to be applied. The placement can be made by using a ASSIMILATE SENSOR plugged into a socket. Repeat the following for each of the socket panels (10 of):

    1. Insert the SENSOR firmly onto the SOCKET.
    2. Apply a ring of Cyanoachrylate Adhesive to the flat side of the COLLAR.
    3. Insert COLLAR over SENSOR, lining up the screw key, an press firmly onto the panel of the SOCKET.
    4. When dry (~10 seconds) carefully remove the sensor.

    AFFIX THE BASE

    The individual instructions for the different MCU varieties will supply the base and the housing.

    1. Assemble the base and housing as instructed.
    2. Connect wires as instructed.
    3. Affix BASE to SHELL with 10 off 4G x 6mm self tapping countersunk screws.

    Step 3: Odds & Sods

    The Socket Caps

    When the Sensor Sockets aren't occupied, the caps offer some protection to the contacts. Rubbing a light oil on the 3P Female headers may stop them accidentally getting glued.

    1. Insert 2 temporary 3P Female Header on 2 3P Male headers to be installed.
    2. Add Cyanoachrylate Adhesive to the exposed short end on the 3P Male headers.
    3. Insert the glue end into the caps and press in firmly.


    The Feet

    If the site for the hub is unstable, raised or inverted, you may want to fix it to a surface. The feet are supplied with the generic shell parts, but they screw into the base of the ICOS HUBS which are specific to a MCU/use-case. They can be screwed on the base in each corner at that stage.


    The Screw-in Collars

    The collars shown throughout this page are the quick install collars. The ASSIMILATE SENSORS can be pushed-in and pulled-off easily. If you need to secure the sensors for any reason, the screw-in collars can be used instead. The 4G x 20mm screw needs to be removed from the individual SENSORS, they are then pressed into the socket (the 3P Female Headers and Key), and a 4G x 30mm cap head self tapping screw is screwed through the collar into the sensor hole.

    Step 4: Next Steps

    Enhancements

    The assembly duration can be shortened by using 6 core ribbon cable, 2x3 IDC Female Sockets and long pin 3P Female headers for the panel socket wiring.

    Already slated is an automatic MQTT publish of any data dumped.

    We are also considering ASSIMILATE ACTORS (relays, indicators, other output) that listen for MQTT commands for topics that are built based on metadata of the ACTOR. So the ACTORS will benefit from the same plug and play architecture.

    3V3 or 5V

    The initial I2C breakouts and pullups will be separated onto a daughter-board handling 3V3 only. This daughter-board will swap out if needed for a logic level converter for both 3V3 and 5V I2C bus. The orange (5V) and yellow (3V3) collars/lids depict the voltage of the sensor/actor.

    Power off during Sleep

    If the MCU will sleep and wake at interval (e.g. 5 minutes), the sensors can be powered off as well. This too will be packaged as a daughter-board, low side switch, cutting the ground to both 5V and 3V3.

    Check out these related builds.