Pololu Jrk 21v3 USB Motor Controller with Feedback

SKU: POLOLU-1392 Brand: Pololu Guides (1)
The jrk 21v3 motor controller is a highly configurable brushed DC motor controller that supports four interface modes: USB, logic-level serial, analog voltage, and hobby radio control (RC). The controller can be used with feedback for closed-loop speed or position control, or it can be used without feedback as an open-loop speed control. The continuous output current is approximately 3 A in the recommended operating range of 8–28 V, with derated performance down to 5 V and transient protection to 40 V. The board ships with connectors included but not soldered in, allowing for custom installations.
$119.95 AUD, inc GST
$109.05 AUD, exc GST

In stock, ships same business day if ordered before 2PM
Delivered by Tue, 18th of Jun

Quantity Discounts:

  • 5-10 $105.77 (exc GST)
  • 10+ $103.59 (exc GST)
- +

1 from local stock, 1 supplier stock; your order will dispatch between Dec 1 to Dec 10. And yes, stock levels and lead times are accurate!

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Shipping:

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  • $10+ Express (2+ days*, tracked)
  • FREE Pickup (Newcastle only - must order online*)

Shipping costs may increase for heavy products or large orders.

Exact shipping can be calculated on the view cart page.

*Conditions apply, see shipping tab below.

Not recommended for new designs: Pololu strongly recommend Pololu's newer and better (and smaller) Jrk G2 21v3 USB Motor Controller with Feedback over this controller, as it offers increased power and many other improvements at the same price. Pololu are continuing to offer the original Jrk 21v3 for now as a legacy product for those with systems designed specifically for this controller.

The Jrk 21v3 is a versatile, general-purpose motor controller that supports a variety of interfaces, including USB. The broad operating range from 5 V to 28 V and continuous output current of 3 A (5 A peak) allow this board to control most small DC brushed motors. Analog voltage and tachometer (frequency) feedback options allow quick implementation of closed-loop servo systems, and a free configuration utility (for Windows) allows easy calibration and configuration through the USB port. A USB A to mini-B cable (not included) is required to connect this controller to a computer.

Key improvements over competing products and earlier Pololu motor controllers with feedback include:

  • USB connectivity with emulated serial (COM) port allows direct motor control from a PC.
  • Ultrasonic PWM to eliminate switching-induced motor shaft hum or whine.
  • Robust, high-speed communication protocol with user-configurable error condition response.
  • High internal resolution (12 bits) for smooth and flexible calibration to various input and feedback devices.
  • Current sensing and limiting.
  • Reversed power protection.
  • Field-upgradeable firmware.

The table below lists the members of the Jrk family, including the original (green) and newer G2 (black) versions, and shows the key differences among them.


Jrk
21v3

Jrk
12v12

Jrk G2
21v3

Jrk G2
18v19

Jrk G2
24v13

Jrk G2
18v27

Jrk G2
24v21
Recommended max
operating voltage:
28 V(1) 16 V 28 V(1) 24 V(2) 34 V(3) 24 V(2) 34 V(3)
Max nominal
battery voltage:
24 V 12 V 24 V 18 V 28 V 18 V 28 V
Max continuous current
(no additional cooling):
2.5 A* 12 A 2.6 A 19 A 13 A 27 A 21 A
USB, TTL serial,
Analog, RC control:
Yes Yes Yes Yes Yes Yes Yes
I²C control: Yes Yes Yes Yes Yes
Hardware current limiting: Yes Yes Yes Yes
Dimensions: 1.35" × 1.35" 1.85" × 1.35" 1.0" × 1.2" 1.4" × 1.2" 1.7" × 1.2"
1 Transient operation (< 500 ms) up to 40 V.
2 30 V absolute max.
3 40 V absolute max.
* Reduced from “3 A” based on newer, more stringent tests. The value now is directly comparable to the rating for the newer G2 21v3.

Main Features of the Jrk 21v3

  • Simple bidirectional control of one DC brush motor.
  • 5 V to 28 V operating supply range.
  • 3 A maximum continuous current output (5 A peak).
  • Four communication or control options:
    1. USB interface for direct connection to a PC.
    2. Full-duplex, TTL-level asynchronous serial interface for direct connection to microcontrollers or other embedded controllers.
    3. Hobby radio control (RC) pulse width interface for direct connection to an RC receiver or RC servo controller.
    4. 0 V to 5 V analog voltage interface for direct connection to potentiometers and analog joysticks.
  • Two closed-loop feedback options:
    1. 0 V to 5 V analog voltage.
    2. Frequency/tachometer digital input up to 2 MHz with 1 ms PID period.
      (Open-loop control with no feedback also available.)
  • Simple configuration and calibration over USB with free configuration program for Windows.
  • Configurable parameters include:
    • PID period and PID constants (feedback tuning parameters).
    • Maximum current.
    • Maximum duty cycle.
    • Maximum acceleration.
    • Error response.
    • Input calibration (learning) for analog and RC control.
  • Optional CRC error detection eliminates communication errors caused by noise or software faults.
  • Reversed power protection.
  • Field-upgradeable firmware.
  • Optional feedback potentiometer disconnect detection.
  • Comprehensive user’s guide.

Specifications

Motor channels: 1
Operating voltage: 5 V to 28 V
Continuous output current: 3 A
Peak output current: 5 A
Auto-detect baud rate range: 300 bps to 115,200 bps
Available fixed baud rates: 300 bps to 115,200 bps
Available PWM frequencies: 20 kHz, 5 kHz
Reverse voltage protection?: Yes
USB connector style: USB Mini-B

The Jrk 21v3 is the smaller of two Jrk motor controllers. For a higher-power version, see the Jrk 12v12.

Included Hardware

The Jrk 21v3 is available in two versions: “fully assembled” with terminal blocks and 0.1" male header pins pre-installed (left picture above), and connector-free (right picture above). The connector-free version includes a straight 0.1" breakaway male header strip and two 3.5mm, 2-pin terminal blocks, but these parts are not soldered to the board, which allows for custom installations.

The three mounting holes are intended for use with #2 screws (not included).

Example Feedback System – 4 Methods of Control

USB control.

TTL serial control.

RC / pulse width control.

Analog control.

Dimensions

Size: 1.35" x 1.35" x 0.4"1
Weight: 0.23 oz

General specifications

Motor driver: MC33926
Motor channels: 1
Control interface: USB; non-inverted TTL serial;
RC servo pulses; analog voltage2
Minimum operating voltage: 5 V
Maximum operating voltage: 28 V
Continuous output current per channel: 3 A
Peak output current per channel: 5 A
Current sense: 0.5 V/A3
Maximum PWM frequency: 20 kHz
Minimum logic voltage: 4 V4
Maximum logic voltage: 5 V
Reverse voltage protection?: Y
Partial kit?: Y
Version: original 21v3 (28 V max, 3 A max continuous)

Notes:

1
Without included hardware.
2
Autodetects baud rates between 300 and 115,200 bps, or can be set to any fixed baud rate in this range.
3
Current readings are converted to a digital number from 0-255.
4
In RC mode, the pulses can be as low as 2V.

Documentation and other information

File downloads

Recommended links

  • The Haunted Organist

    A spooky animatronic skeleton using the Jrk USB Motor Controller. See the final result. By Mark Goodson, October 2009.

  • R2D2 dome position control

    A replica of the famous Star Wars droid R2D2 that uses the Jrk USB Motor Controller for position control. See the video which shows the Jrk Configuration Utility in action, or read the blog post which has more information. By ggpipe, February 2010.

  • Microsoft .NET Framework 3.5

    The Microsoft .NET Framework version 3.5 is required for many Pololu configuration, control, and utility programs under Windows. Most computers will have this installed already or can automatically install it over the internet, but you can also get .NET 3.5 directly from Microsoft at this link. If you are installing on a computer without internet access, make sure to get the Full Redistributable Package.

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.

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