Wiring Circuit

Solder the MCP9808 sensor and slide switch to the pins on the Feather nRF52840. 10-wire 28AWG silicone covered wire is suggested. Use the following wire lengths:

MCP9808 4-Wire Cable
160mm (6.3in)

Slide Switch 2-Wire Cable
50mm (2in)

The ground pin on Feather nRF82840 is shared across the slide switch and the MCP9808

Install Feather nRF52840

Place the Feather PCB on top of the standoffs on the bottom cover. Reference the photo for correct placement. Insert the PCB at an angle so the edge is underneath one of the tabs. Fit one of the mounting holes onto one of the standoffs.

Secure Feather

Firmly press the PCB down so it clips under the second tab. The two tabs will keep the Feather secured in place. Ensure the second mounting hole is properly fitted onto the standoff.

Installed PCB

The Feather PCB should be flush like shown in the photo. A clearance of 2mm allows for wiring on the bottom.

Installing Switch

Insert the body of the slide switch to the built-in holder on the bottom cover. Firmly press the switch into the holder to secure it in place.

Installed Switch

The actuator should be accessible on the outside of the holder.

Install Parts

The 400mah lipo battery can be secured in place with double-sided tap or mounting tack. Double check the slide switch and Feather nRF52840 are properly installed.

Install Flexible Strap

Insert the tabbed end of the strap to the slotted tab on the bottom cover closest to the Feather. 

Install MCP9808

Place the MCP9808 PCB over the two nubs on the end of the flexible strap. Firmly press the nubs into the two mounting holes on the MCP9808 PCB.

Installed MCP9808

The nubs are essentially squeezed into the mounting holes – This is only possible with flexible material like Ninjaflex, Cheetach or TPU filament.

Install Sensor Cover

Slip the cover onto the flexible strap to protect the MCP9808 sensor. The center hole in the cover should be properly lined up with the temperature sensor – if not, reverse the orientation of the cover.

Installing MCP9808 Wiring

Pinch the flexible strap to open up the channel in the middle of the band. Begin to fit the 4-wire ribbon cable into the channel. Press wiring down so it's flattened into place.

Installed Wiring

The silicone covered ribbon cable provides a nice grip combined with the flexible strap. By Design, the wiring will be kept in place when bending the strap inwards or outwards.

Install Case to Bottom

The case snap fits onto the bottom cover. Line up the cutouts with the features on the bottom cover. The case features a cutaway for the sensor wiring.

Sensor Wiring Clearance

The wiring from the sensor is fitted through the opening on the side of the case.

Install Loop Band to Strap

Insert the loop band through the end on the flexible strap.

Tension Loop

Grab the nub end of the loop brand and fit it through the two slots. Reference the photo for correct installation.

Installed Loop Band

Fit the nub end of the loop band through the slotted tab on the bottom cover. Firmly press the nub end through.

USB Access

The USB port is accessible for recharging the 400mah lipo battery and reprogramming.

Power Switch

Use the slide switch to power the circuit on and off.

Assembled Case

And there we have it! The case is assembled and ready to wear.

This guide was first published on Apr 07, 2020. It was last updated on Apr 19, 2024.

This page (Assembly) was last updated on Mar 08, 2024.

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