Overview
With integrated support for analog voltage or tachometer (frequency) feedback, the second-generation G2 family of Jrk motor controllers makes it easy to add closed-loop control of speed or position (but not both!) of a single brushed DC motor to a variety of projects. These versatile, general-purpose modules support five different 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. They also offer many settings that can be configured using our free configuration software utility. This software simplifies initial setup of the device and allows for in-system testing and monitoring of the controller via USB (a micro-B USB cable is required to connect the Jrk G2 to a computer).
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The table below lists the members of the Jrk family, including the original (green) 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 |
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| 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 |
| TTL serial, USB, Analog, RC control: |
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| I²C control: | |
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| Hardware current limiting: | |
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| Dimensions: | 1.35″ × 1.35″ | 1.85″ × 1.35″ | 1.0″ × 1.2″ | 1.4″ × 1.2″ | 1.7″ × 1.2″ | ||
| Price: | $49.95 | $99.95 | $49.95 | $99.95 | $99.95 | $149.95 | $149.95 |
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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. |
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Main features of the Jrk G2 family
- 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 pulse counting (for higher-frequency feedback) or pulse timing (for lower-frequency feedback), for closed-loop speed control
- 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
- Configurable parameters include:
- PID period and PID constants (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
Details for item #3149
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The Jrk G2 24v21 operates from 6.5 V to 40 V and can deliver a continuous output current of 21 A without a heat sink. Note that 40 V is the absolute maximum for this controller; the maximum recommended operating voltage is 34 V, and the maximum recommended nominal battery voltage is 28 V.
If you need to identify which version you have, you can just plug it into a computer through USB and the Jrk software will tell you. For quick visual identification without a computer, you can distinguish this version from the identically sized Jrk G2 18v27 by the number 100 on top of the tall silver electrolytic capacitors.
Included hardware
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The Jrk ships with a 0.1″ breakaway male header strip and two 2-pin 5mm terminal blocks. You can solder the terminal blocks to the four large through-holes to make your motor and motor power connections (see our short video on terminal block installation), or you can solder an 8-pin piece of the 0.1″ header strip into the smaller through-holes that border these larger holes. Note, however, that the terminal blocks are only rated for 16 A, and each header pin pair is only rated for a combined 6 A, so for higher-power applications, thick wires should be soldered directly to the board.
Pieces from the 0.1″ header strip can be soldered into the small holes on the logic connection side of the board to enable use with solderless breadboards, perfboards, or 0.1″ connectors, or you can solder wires directly to these holes for the most compact installation.
Note: A USB A to micro-B cable (not included) is required to connect the Jrk G2 to a computer for initial configuration.
The Jrk ships with a 0.1″ breakaway male header strip and two 2-pin 5mm terminal blocks. You can solder the terminal blocks to the four large through-holes to make your motor and motor power connections, or you can solder an 8-pin piece of the 0.1″ header strip into the smaller through-holes that border these larger holes. Note, however, that the terminal blocks are only rated for 16 A, and each header pin pair is only rated for a combined 6 A, so for higher-power applications, thick wires should be soldered directly to the board.
A 10-pin piece of the 0.1″ header strip can be soldered into the small holes on the logic connection side of the board to enable use with solderless breadboards, perfboards, or 0.1″ connectors, or you can solder wires directly to these holes for the most compact installation.
Note: A USB A to micro-B cable (not included) is required to connect the Jrk G2 to a computer for initial configuration.
Differences from the original Jrk motor controllers
The Jrk G2 family features a number of improvements compared to our original two Jrk motor controllers (21v3 and 12v12). Most importantly, the Jrk G2 controllers support both higher operating voltages and larger output currents while being even more compact than their predecessors. Other new features include:
- Hardware current limiting – the motor driver on the Jrk G2 uses current chopping to actively limit the motor current when it exceeds a software-configurable threshold
- More accurate speed control at low tachometer frequencies
- I²C interface provides an additional control option
- VIN measurement capability allows monitoring of battery or power supply
- USB Micro-B connector (instead of Mini-B as on the original Jrk controllers)
