Pololu TReX Jr Dual Motor Controller DMC02

SKU: POLOLU-767 Brand: Pololu

Retired Product

Replaced by: POLOLU-1365
This product has been replaced by: POLOLU-1365
This product is no longer available. This page is only for reference.

Newer Motor Controllers Available! Pololu generally recommend Pololu's newer, easier-to-use Simple Motor Controllers over the TReX. The Simple Motor Controllers can accept RC, analog, or TTL serial inputs. Additionally they have a USB interface for quick configuration (no need for an external USB-to-serial converter like with the TReX). Pololu's newest G2 Simple Motor Controllers can also be controlled through I²C and have configurable current limiting. Each Simple Motor Controller only has a single motor channel, but they can be connected in mixing mode and used with two analog or RC joystick channels (x and y axes) to control both the motors in a differential drive robot just like the TReX. Note that unlike the TReX, the Simple Motor Controller does not have an RS-232 interface or serial override feature.

Pololu TReX Jr bottom with labels and dimensions

A novel blend of serial, RC, and analog motor control

The TReX Jr Dual Motor Controller, a lower-power version of theTReX Dual Motor Controller, is a versatile DC motor controller designed to seamlessly blend autonomous and human control of small robots. The TReX Jr can control two bidirectional and one unidirectional motor via three independent control interfaces:radio control (RC) servo pulses, analog voltage, and asynchronous serial (RS-232 or TTL). Using the compact MC33887 motor driver allows for a single-board design that reduces cost while maintaining a small package. As an added benefit, the use of the MC33887 motor driver allows operation to 24 V.

The TReX Jr uses five input channels to receive the RC or analog control signals. When operating in RC or analog mode, the five channels function as follows:

  • Channel 1: motor 1 speed and direction or, if in mix mode, turn left/right
  • Channel 2: motor 2 speed and direction or, if in mix mode, go forward/reverse
  • Channel 3: auxiliary (unidirectional) motor speed
  • Channel 4: can be used to enable “flipped mode”, which allows invertable robots to be controlled as normal when they are inverted
  • Channel 5: determines whether the motors are controlled by the channel inputs or the serial interface; this channel allows you to switch between autonomous and human control at will

The serial interface can switch instantly with one of the other two interfaces, allowing mixed autonomous and remote control. For example, a robot could be configured to run autonomously most of the time, but a human operator could override the autonomous function if the robot gets stuck or into a dangerous situation. If the serial mode is selected as the primary interface, high-resolution measurements of all five channel input signals (be they RC pulses or analog voltages) are made available to the autonomous robot controller, allowing for complex and unlimited mixing of operator control and sensor input. For example, the TReX would be a great motor controller for a remotely controlled balancing robot.

Pololu TReX Jr Dual Motor Controller with labels

Technical specifications

Dimensions1.75" x 1.75" x 0.5" (0.3"height without connectors)
Supply voltage5 – 24 V
Primary motor outputs2 bidirectional, 5 A peak, up to 2.5 A continuous (may be combined to control 1 bidirectional,5 A continuous)
Auxiliary output1 unidirectional, 10 A continuous
Speed control128 steps in each direction
Control interfacesRC servo pulses, analog voltages, or serial commands; master interface set by mode-select jumper
Input channels5 (RC servo pulses or analog voltages)
RC pulse measurements12-bit resolution, 1 us accuracy
Analog measurements10-bit resolution
Serial interfaceboth RS-232 and TTL (logic level), bidirectional
Baud ratessupports 11 common baud rates ranging from 1200to 115,200 bps
Expanded protocolAllows multiple Pololu servo and motor controllers on one serial line
Compact protocolAllows both motors 1 and 2 to be simultaneously set with just three bytes

RC/Analog control features

  • Battery Elimination Circuit (BEC) jumper lets the TReX Jr optionally power your RC receiver or analog controller
  • mix-mode jumper allows for single-stick motor control of differential-drive robots
  • automatic calibration for your particular RC or analog controller (the TReX Jr can learn the channel ranges)

Options accessable through the serial interface

  • all five high-resolution channel input values are available
  • remapped channel input values show what the TReX Jr would do if it were in control
  • optional 7-bit cyclic redundancy checking to ensure command/data validity
  • calibration values can be explicitly read and set
  • each channel can be reversed and parabolically scaled
  • current limit, acceleration, and maximum motor speed settings
  • the bidirectional motors can (individually) be set to coast or variable brake when in the deadband
  • upgradable firmware

Safety features

  • “safe-start” requirements prevent accidental motor activation at power-up
  • optional automatic motor shutdown on serial error, timeout, or input channel noise

Note: The TReX Jr does not require use of the serial interface to function; it will work right out of the box as an electronic speed control (ESC). You will not have access to the full suite of features the TReX Jr provides if you do not make use of the serial interface, though.

24" (600 mm) female-female RC servo extension cable.

Servo cable accessories

The TReX Jr has male 0.1" headers; for direct connection to an RC receiver or serial servo controller, Pololu recommend ordering one 6" female-to-female cable, 12" female-to-female cable, or 24" female-to-female cable per channel you intend to use (the TReX Jr can use up to five channels).

People often buy this product together with:

Servo Extension Cable 6" Female - FemaleServo Extension Cable 6" Female - Female

Dimensions

Size: 1.75" x 1.75" x 0.5"
Weight: 15 g

General specifications

Motor driver: MC33887
Motor channels: 31
Control interface: non-inverted TTL serial (2-way); RS-232 serial (1-way),
RC servo pulses, analog voltage
Minimum operating voltage: 5 V
Maximum operating voltage: 24 V
Continuous output current per channel: 2.5 A2
Peak output current per channel: 5 A3
Continuous paralleled output current: 5 A
Current sense: 0.5 V/A4
Maximum PWM frequency: 10 kHz
Minimum logic voltage: 2.7 V
Maximum logic voltage: 5.5 V
Reverse voltage protection?: Y

Notes:

1
Two bidirectional, one unidirectional.
2
On primary channels.
3
On the primary channels.
4
Current readings are converted to a digital number from 0-255.

Documentation and other information

File downloads

Recommended links

  • Arduino example code for the TReX

    This Arduino sketch, written by forum member mwomack, sets up a serial interface between the TReX and an Arduino and sends three basic data-query commands: “Get Signature”, “Get Mode”, and “Does Serial Control Motors?”. It can be used as a template for implementing additional commands.

  • More Arduino example code for the TReX

    This Arduino sketch, written by forum member gcebiker, sets up a serial interface between the TReX and an Arduino and sends commands to drive motors in response to joystick inputs to the Arduino.

  • Video of the RP5 Tracked Chassis Driven by the TReX Jr

    A video showing the RP5 Tracked Chassis as a radio-controlled platform driven by the Pololu TReX Jr motor controller.

This product is listed in:

Retired

Product Comments

Exact shipping can be calculated on the view cart page (no login required).

Products that weigh more than 0.5 KG may cost more than what's shown (for example, test equipment, machines, >500mL liquids, etc).

We deliver Australia-wide with these options (depends on the final destination - you can get a quote on the view cart page):

  • $3+ for Stamped Mail (typically 10+ business days, not tracked, only available on selected small items)
  • $6+ for Standard Post (typically 6+ business days, tracked)
  • $10+ for Express Post (typically 2+ business days, tracked)
  • Pickup - Free! Only available to customers who live in the Newcastle region (must order online and only pickup after we email to notify you the order is ready). Orders placed after 2PM may not be ready until the following business day.

Non-metro addresses in WA, NT, SA & TAS can take 2+ days in addition to the above information.

Some batteries (such as LiPo) can't be shipped by Air. During checkout, Express Post and International Methods will not be an option if you have that type of battery in your shopping cart.

International Orders - the following rates are for New Zealand and will vary for other countries:

  • $11+ for Pack and Track (3+ days, tracked)
  • $16+ for Express International (2-5 days, tracked)

If you order lots of gear, the postage amount will increase based on the weight of your order.

Our physical address (here's a PDF which includes other key business details):

Unit 18, 132 Garden Grove Parade
Adamstown
NSW, 2289
Australia

Take a look at our customer service page if you have other questions such as "do we do purchase orders" (yes!) or "are prices GST inclusive" (yes they are!). We're here to help - get in touch with us to talk shop.

Have a product question? We're here to help!

Write Your Own Review

Guides

The Maker Revolution

The Maker Revolution celebrates the creation of new devices and the modification of existing ones - ...
The Maker Revolution celebrates the creation of new devices and the modification of existing ones - ...

Projects

Raspberry Pi Video Looper Display Installation | Overshare Video Festival

IntroductionA suspended ceiling display of forty repurposed screens and displays, each screening cr...
IntroductionA suspended ceiling display of forty repurposed screens and displays, each screening cr...

Mailbox Delivery Notification System

Introduction During the Covid lockdown, I needed something to do. The Postman or woman does not de...
Introduction During the Covid lockdown, I needed something to do. The Postman or woman does not de...

PiicoDev Schematic System

Introduction: Hi everybody. Over the past few weeks, I have been working on an intuitive system th...
Introduction: Hi everybody. Over the past few weeks, I have been working on an intuitive system th...
Feedback

Please continue if you would like to leave feedback for any of these topics:

  • Website features/issues
  • Content errors/improvements
  • Missing products/categories
  • Product assignments to categories
  • Search results relevance

For all other inquiries (orders status, stock levels, etc), please contact our support team for quick assistance.

Note: click continue and a draft email will be opened to edit. If you don't have an email client on your device, then send a message via the chat icon on the bottom left of our website.

Makers love reviews as much as you do, please follow this link to review the products you have purchased.