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Bricktronics Motor Driver

Bricktronics Motor Driver
Want to use LEGO Mindstorms NXT motors with your microcontroller development board? The Bricktronics Motor Driver lets you connect two NXT motors to our injection-molded NXT-compatible sockets, with the necessary electronics to allow your microcontroller to control the motors, plus get position feedback from the motors. Now available for purchase in the Wayne & Layne Store.

Features:

  • Supports two LEGO NXT motors:
    • Bi-directional speed and position control
    • Support for reading the position feedback from the encoders
  • High-current motor driving chip to handle high-torque and high-speed motor loads
  • Uses standard LEGO NXT cables
  • Works with any 5 volt compatible microcontroller
  • Pre-assembled circuit board, available either with or without header pins attached
  • Two convenient mounting holes for 4-40 or M3 screws.

Bricktronics Motor Driver

Kit contents and assembly instructions:
This kit is mostly pre-assembled, and comes in two configurations: With header pins attached, and without header header pins attached. If you want to attach your own wiring, the configuration without header pins attached will be the best choice (left image below). If you want to plug the motor driver right into a breadboard, the configuration with header pins attached will save you time and effort (right image below).

With headers installedWithout headers installed


What you need
The Bricktronics Motor Driver connects any 5v-compatible microcontroller to two LEGO NXT motors. Microcontroller, motors, and cables are not included. Both the LEGO Mindstorms NXT 2.0 motors and the LEGO Mindstorms EV3 motors are compatible with the Bricktronics Motor Driver.

Motors need more power than most electronics, and the LEGO NXT motors have special power requirements. You typically need between 600 – 1000 mA of current per motor, depending on motor speed and load. The LEGO NXT motors need between 7.2 and 9 volts for driving the motor, and also need between 4.3 and 5 volts for the encoder position feedback circuits. To power your stationary creations, our 9 volt 2000 mA wall adapter works great. If you want to power your creations on the go, our 6AA battery pack works well.

Software Libraries
The software libraries for the Bricktronics products was completely redesigned in 2015. The all-inclusive Bricktronics library has been broken into one library per motor/sensor, making it easier to add support for new sensors as well as making it easier to port the libraries to non-Arduino platforms. The new BricktronicsMotor library includes support for any use of the LEGO motors, including with the Bricktronics Shield, Bricktronics Megashield, or the new Bricktronics Motor Driver.

Electrical Interface
The Bricktronics Motor Driver board has 15 pins, divided into three parts: One set of five pins are for the power supply connections, and two sets of five pins are for the two motors.

Power supply connections:

To power the circuit board and the motors, provide a ground connection (GND), 5 volts DC (VCC), and your motor voltage (VM). LEGO NXT motors can be driven with up to 9v. Because motors require lots of current (up to an amp per NXT motor under heavy load), there are two connections each for GROUND and VM. If you are using both motors in a high-load situation, please use both connections for GND and VM. The 5v VCC is used to power the logic circuits in the motor driver chip, as well as powering the encoder position feedback in the motors.

Motor control and feedback connections:

Each motor has five connections:

  • Enable (EN) – Drive this pin low to disable the motor drivers, drive this pin high to enable motor drivers.
  • Direction (DIR) – Setting this pin high/low will drive the motor either clockwise or counter-clockwise.
  • Speed (PWM) – Once you enable the motor drivers and have set your direction, provide a pulse-width modulated signal to this pin to control the motor’s speed.
  • Encoder Tachometer pins (T1 and T2) – These two pins provide a quadrature encoded signal that tracks the motor’s rotation. More details here.

Closeup of motor driver interface pins

Open Source Hardware
This kit is open source hardware. We make the hardware source files like the schematic and the pcb files available for anyone to use as long as they credit us and release any modifications as open source hardware. The schematic and pcb files are available on the Bricktronics download page.

Note: Wayne and Layne, LLC and our products are not connected to or endorsed by the LEGO Group. LEGO, Mindstorms, and NXT are trademarks of the LEGO Group.