The following shows how the parts are wired together. Assembly of the timer involves some creative use of wire length to suspend the QT Py and LIS3DH between the two rings.

  • Data In on ring one to A3 on QT Py
  • V+ on ring one to 5V on QT Py
  • Gnd on ring one to GND on QT Py
  • Gnd on ring two to GND on ring one
  • V+ on ring two to V+ on ring one
  • Data In on ring one to Data Out on ring two
  • LIS3DH to QT Py using STEMMA QT cable

Assembly

Begin by soldering the three wires to each ring, using piece of wire 5-6 inches in length.

Solder the blue wire to In (data input), the black wire to G (power signal ground), and the red wire to V+ (power 5V DC) on both rings. Solder the data input wire first, and follow the pattern indicated in the second image where green indicates the through-hole to use to solder the wire, and red indicates a through-hole to skip.

Trim any excess wire sticking up above the LEDs.

Choose a ring to be ring one.

Bend the wires on ring one to match the locations of the pins on the QT Py, with enough wire to suspend the QT Py above the ring.

The blue wire should match A3, the red wire should match 5V and the black wire should match GND.

Make sure the QT Py is parallel to the ring - if you lay the ring flat on your desk, the QT Py should also be horizontal.

Solder the wires to the QT Py.

On ring two, bend the signal (blue) and ground (black) wires around the ring so they match the Data Out and GND pins on ring one. You can hold the rings together to line up the wires and bend them until they are correct.

The red wire does not need to be bent and can connect directly from ring two to ring one.

Trim the wires so less than an inch is sticking up from the ring. The lengths should all be equal.

Solder ring two to ring one with the blue wire to Out (data output), the black wire to G (power signal ground), and the red wire to V+ (power 5V DC).

Trim any excess wire sticking up above the LEDs.

Gather the soldered QT Py and ring assembly, the double-sided foam tape, the STEMMA cable and the LIS3DH.

Attach the double-sided foam tape to the QT Py. This version required layering two pieces of foam tape together.

Plug the LIS3DH into the QT Py using the STEMMA QT connectors and cable.

Wind the cable and the LIS3DH through the rings so the cable is to the side of the LIS3DH and QT Py.

Use double-sided foam tape to attach the LIS3DH to the back of the QT Py. The LIS3DH should also be parallel to the rings - when you set the timer on the front of either of the rings, the LIS3DH and QT Py should both be horizontal.

You're ready to start timing!

Optional Diffusers

NeoPixel LEDs are quite bright. It's possible to control the brightness using CircuitPython, but you may also want to add diffusers to the rings. Here is a simple way to add some physical diffusion to the LEDs on the timer.

Get some double-sided tape and a piece of white or similarly light colored card stock, or other thicker paper product.

Use a ring as a guide to cut two circles out of card stock. Cut two strips the same length as the diameter of the circles, and round the corners of the strips.

Use a piece double-sided tape in the center of each strip to attach the strips to the circles.

Gently bend the strips away from the circles on each end to make two flaps on each diffuser.

Slip the flaps inside the ring to attach the diffuser to the ring. Orient them so the flaps are not blocking the USB port on the QT Py.

That's it!

This guide was first published on Oct 22, 2020. It was last updated on Oct 22, 2020.

This page (Assembly) was last updated on Feb 18, 2021.

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