1. Overview

Pololu Jrk 21v3 USB motor controller with dimensions.

Bottom of the Jrk 12v12 USB motor controller with feedback with dimensions.

The jrk family of versatile, general-purpose motor controllers supports a variety of interfaces, including USB. 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.

There are two different jrk motor controllers:

The jrk 21v3 has a broad operating range from 5 V to 28 V. The continuous output current of 3 A (5 A peak) allow this board to control most small DC brushed motors.

The jrk 12v12 has an operating range from 6 V to 16 V. The high continuous output current of 12 A (30 A peak) allow this board to control many medium-sized DC brushed motors

Main Features of the Jrk 21v3

• 5 V to 28 V operating supply range.
• 3 A maximum continuous current output (5 A peak).
• Automatic motor driver shutdown on under-voltage, over-current, and over-temperature conditions.

Main Features of the Jrk 12v12

• 6 V to 16 V operating supply range.
• 12 A maximum continuous current output (30 A peak).

Main Features of all Jrk Motor Controllers

• Simple bidirectional control of one DC brush motor.
• Four communication or control options:
  • USB interface for direct connection to a PC.
  • Full-duplex, TTL-level asynchronous serial interface for direct connection to microcontrollers or other embedded controllers.
  • Hobby radio control (RC) pulse width (PWM) interface for direct connection to an RC receiver or RC servo controller.
  • 0–5 V analog voltage interface for direct connection to potentiometers and analog joysticks.
• Two closed-loop feedback options:
  • 0–5 V analog voltage.
  • 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 (Windows 10, Windows 8, Windows 7, Vista, Windows XP compatible).
• 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.

Specifications

_	Jrk 21v3	Jrk 12v12
Motor channels:	1	1
Operating voltage:	5 – 28 V	6 – 16 V
Continuous output current:	3 A	12 A
Peak output current:	5 A	30 A
Auto-detect baud rate range:	300 – 115,200 bps	300 – 115,200 bps
Available fixed baud rates:	300 – 115,200 bps	300 – 115,200 bps
Available PWM frequencies:	20 kHz, 5 kHz	20 kHz, 5 kHz
Reverse voltage protection?:	Yes	Yes
USB connector style:	USB Mini-B	USB Mini-B

Included Hardware

The jrk 21v3 and jrk 12v12 each ship with a straight 0.1″ breakaway male header strip and two appropriately sized 2-pin terminal blocks (3.5 mm pitch for the 21v3 and 5 mm pitch for the 12v12). To provide maximum flexibility, none of these parts are soldered to the board (unless you ordered our fully assembled jrk 21v3, which ships with these parts soldered in as shown in the assembled jrk 21v3 picture above).

For the most compact installation, you can solder wires directly to the jrk pads themselves and skip using the included hardware. The included hardware allows you to make less permanent connections. You can break the header strip into smaller pieces, such as an 8×1 piece and two 3×1 pieces, and solder these strips into the jrk’s I/O pads.

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

Note: A USB A to mini-B cable (not included) is required to connect this device to a computer.