rbx motor assembled

The Motor Brick is based on a 6V DC dual-axle geared motor that is commonly used for Arduino robotics.

dc motor dual axis geared

It is paired with a L9110H driver IC for motor control.

L9110 motor driver  L9110 pinout

The connections required are shown below:

rbx motor schematic

The JST RCY connector from the Motor Power Brick is used to power both the L9110 and the motor.

Control signals to IA and IB are supplied via the 4-pin JST XH connector from the Microcontroller Brick to control the speed of the motor.

Parts list

6V DC dual-axle geared motor 1
L9110H motor driver IC 1
4-pin JST XH connector (male) 1
2-pin JST RCY connector (male) 1
M2 self-tapping screw 3


Although it is possible to solder directly to the L9110H IC, I find it much easier to make the connections using a small piece of prototype board.

rbx motor circuit 01  rbx motor circuit 02

Start by soldering 2 short pieces of wire to pin 1 (OA; green wire in photo) and pin 4 (OB; purple wire in photo) of the L9110.

rbx motor circuit 03

Solder a 2-pin JST RCY female connector to pin 2 (VCC) and pin 8 (GND) of the L9110.

rbx motor circuit 04

Bridge pin 2 and pin 3 (both VCC) with an extra bit of solder.

rbx motor circuit 05

Solder a 4-pin JST XH female connector to the L9110. Cut off the red wire since we won't be needing it. Solder the black wire to pin 5 (GND), white wire to pin 6 (IA) and yellow wire to pin 7(IB). 

rbx motor circuit 06

Bridge pins 5 and 8 (GND) with a short piece of wire.

rbx motor circuit 07

This is how it looks IC side up.

rbx motor circuit 08

With the motor leads positioned as shown in the photo, solder the green wire (OA; pin1) to the top lead, and purple wire (OB; pin 4) to the bottom lead.

rbx motor circuit 09

Secure the L9110H assembly to the motor housing with some hot glue.

rbx motor circuit 10


Print the enclosure parts on a 3D printer.

rbx motor 3dview

Insert the DC motor into the longer portion of the enclosure. The slot located at the back of the enclosure lets the connectors exit and is situated on one side. You should insert the DC motor such that the mounted L9110 assembly is located on that side. 

Also insert the two axle adapters onto the motor axle. One axle adapter is slightly longer than the other. The longer adapter is meant to be mounted on the same side as the L9110 assembly. It compensates for the asymmetry introduced by the extra space allowed for the controller so that when everything is put together, the axle adapters protrude the same distance from the enclosure.

rbx motor assembly 01 rbx motor assembly 02

Mount the front portion of the enclosure and secure with 2 x M2 screws. 

rbx motor assembly 04

Insert the cover piece at the back where the wires exit, and secure with a M2 screw.

rbx motor assembly 03

Line up two 2x1 brickbases on a faceplate, two rows apart. Surround the brickbases with a few other bricks to assist in alignment.

rbx motor assembly 05

Add two drops of superglue on each brickbase and mount the module, with the back of the module in line with the brickbases at the back. Press and hold for 60s.

rbx motor assembly 06

The brickbases at the back should line up with the back of the enclosure.

rbx motor assembly 07

The finished module:

rbx motor assembled

The motor will still have a little room to move within the enclosure. Mount the enclosure on a faceplate with walls on each side, and insert an axle into each side of the motor. Jiggle the motor slightly so that the axles are perfectly aligned in the holes with the least tension.

rbx motor assembly 08

Secure the motor brick by adding a little hot glue both at the front, and (optionally) at the back.

rbx motor assembly 09 rbx motor assembly 10

As with the superglue, you don't want to overdo this because it can make it harder to disassemble the module if it is ever required. Inject just a tiny glob, and press it down using the body of a screwdriver.