1. Overview

The second-generation Jrk G2 motor controllers are designed to enable easy closed-loop speed control or position control (but not both!) of a single brushed DC motor. They feature integrated support for analog voltage or tachometer (frequency) feedback and a variety of control interfaces–USB for direct connection to a computer, TTL serial and I²C for use with a microcontroller, RC hobby servo pulses for use in an RC system, and analog voltages for use with a potentiometer or analog joystick. A free configuration utility simplifies initial setup of the device, provides access to a wide array of configurable settings, and allows for in-system testing and monitoring of the controller via USB.

Side-by-side comparison of the different Jrk G2 USB Motor Controllers with Feedback.

The table below lists the members of the Jrk G2 family and shows the key differences among them.

	Jrk G2 21v3	Jrk G2 18v19	Jrk G2 24v13	Jrk G2 18v27	Jrk G2 24v21
Minimum operating voltage:	4.5 V(1)	6.5 V	6.5 V	6.5 V	6.5 V
Recommended max operating voltage:	28 V(2)	24 V(3)	34 V(4)	24 V(3)	34 V(4)
Max nominal battery voltage:	24 V	18 V	28 V	18 V	28 V
Max continuous current (no additional cooling):	2.6 A	19 A	13 A	27 A	21 A
Dimensions:	1.0″ × 1.2″	1.4″ × 1.2″		1.7″ × 1.2″

1 The 5V logic voltage drops when powered from a supply below about 5.2 V.
2 Transient operation (< 500 ms) up to 40 V.
3 30 V absolute max.
4 40 V absolute max.

Features and specifications

• Easy open-loop or closed-loop control of one brushed DC motor
• A variety of control interfaces:
  • USB for direct connection to a computer
  • TTL serial operating at 5 V for use with a microcontroller
  • I²C for use with a microcontroller
  • RC hobby servo pulses for use in an RC system
  • Analog voltage for use with a potentiometer or analog joystick
• Feedback options:
  • Analog voltage (0 V to 5 V), for making a closed-loop servo system
  • Frequency, for closed-loop speed control using pulse counting (for higher-frequency feedback) or pulse timing (for lower-frequency feedback)
  • None, for open-loop speed control
  • Note: the Jrk does not support using quadrature encoders for position control
• Ultrasonic 20 kHz PWM for quieter operation (can be configured to use 5 kHz instead)
• Simple configuration and calibration over USB with free configuration software utility (for Windows, Linux, and macOS)
• Configurable parameters include:
  • PID period and PID coefficients (feedback tuning parameters)
  • Maximum current
  • Maximum duty cycle
  • Maximum acceleration and deceleration
  • 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

Jrk G2 21v3 USB Motor Controller with Feedback, bottom view with dimensions.

Jrk G2 18v19 USB Motor Controller with Feedback, bottom view with dimensions.

Jrk G2 18v27 USB Motor Controller with Feedback, bottom view with dimensions.

Note: This guide only applies to the Jrk G2 motor controllers, which have black circuit boards. If you have one of the first-generation Jrk 21v3 or Jrk 12v12 controllers, which have green circuit boards, you can find their user’s guide here.