PCB Adapter: LEGO Bricks to Qwiic Sensors

By Rachael Azrialy, Tufts University

This guide will walk you through the steps and materials needed to fabricate a PCB that can connect your LEGO Brick to Qwiic Sensors to expand the possibilities of your projects!

1. 1 Dual Bidirectional I2C Bus and SMBus Repeater (PCA9515BDGKR)
2. 2 10kohm resistors SMD (CHP0805AFX-1002ELF)
3. 1 Qwiic connector SMD (PRT-14417)
4. Qwiic cables (at least one, any length)
5. Qwiic sensors (at least one)
6. 1.6mm thick acrylic
7. Super glue
8. Solder paste
9. Heat gun
10. Tweezers (optional)

Find and use the qwiic_gerb zipped folder that contains the gerber files for this PCB in this Github repository to download and order the printed circuit boards. Ensure the thickness is 1.6mm when ordering.

Use the qwiic_laser dxf file in this Github repository to laser cut the second layer of the adapter. Ensure the acrylic is 1/16in (~1.6mm).

Use superglue to glue the final laser cut acrylic you obtained in step 2 to the PCB. Ensure they are properly lined up, otherwise it will not fit in the LEGO Brick. This should make the thickness 3.2mm, which is the needed thickness for the LEGO Brick's socket.

Due to the small size of the electrical components that need to be soldered, solder paste allows for the most ease.

Place solder paste on the pads on the PCB and place the components on the PCB (ensure the chip is oriented so the 2A text on top of it is on the side closest to the Qwiic connector) Using the heat gun, heat up the solder paste to solder all components on the PCB.

Connect the adapter PCB to Port A in the LEGO Brick, and attach the Qwiic sensor to the PCB, as depicted in the photo.