Place a piece of woven fabric in a 6-inch or larger embroidery hoop.

Arrange eight sewable NeoPixels in a heart on your fabric.

Trace around your pixels with a pencil or a disappearing-ink embroidery pen.
Start stitching the data lines between each pixel according to the circuit diagram. Begin by bringing the thread from back to front, leaving a 6-inch tail, and stitching around the inward facing arrow of one pixel, piercing through the fabric from front to back. Repeat a few times to secure the pixel to the fabric. Tie the tail in a knot with the working thread at the back.
Use a running stitch to make your way to the outward-facing arrow on the next pixel, using your trace marks for guidance in pixel placement.

After you've stitched around the pixel's pad a few times, tie the thread in a knot at the back.

Apply tension to thread tails and dab clear nail polish onto the knots.

Allow to dry, periodically tugging on the thread tails to keep the knots tight.

Only clip thread tails short when completely dry to prevent unraveling!

Continue making short connections between each pixel's data connections, making sure the arrows all point in the same direction along the chain. Refer to the circuit diagram.
Use a running stitch to trace around the perimeter of the heart, connecting to each pixel's power (+) pad as you go. Connect this thread to Vout on GEMMA at the back.

Use another thread and running stitch to connect up all the ground (-) pads of the pixels, circling the inner perimeter of the heart. Connect this thread to GND on GEMMA at the back.

Connect the first pixel's inward-facing arrow to D1 on GEMMA.

Tie off and seal all knots before trimming thread tails.

Put a piece of tape or fabric behind GEMMA where it overlaps any stitches it shouldn't touch.
Use a multimeter in continuity-testing mode to test out your circuit. Make sure power isn't connected to ground, and verify that all points that should be connected are, indeed, connected.

Plug in the USB cable and test out the pixels using the strandtest sketch included in the Adafruit NeoPixel library for Arduino (change the value of PIN to 1 before compiling).

Are they all working? Great! If not, unplug and re-evaluate your circuit. Clean up any frayed or loose bits of thread, re-stitch any loose spots and double-seal your knots. Probe again with your multimeter before reconnecting via USB.

If you're happy with the flashing lights, you're done! Sew your new circuit swatch into a brooch or onto your Valentine's outfit, and rock your new flashy accessory.

But if you want your heart to turn on only when the moment's right, continue on to add a light sensor, perfect for revealing your heart from under a jacket, hat, or hemline.

The circuit isn’t finished yet, but let’s get the final code onto the board before continuing, so we can test it along the way…

This guide was first published on Feb 26, 2014. It was last updated on Sep 30, 2017.

This page (Stitch Circuit) was last updated on Feb 14, 2014.

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