New G2 Simple Motor Controllers

Posted by Jan on 15 November 2018
Tags: new products

Last week, we released updated (G2) versions of our Simple Motor Controllers. We released our original Simple Motor Controllers just over eight years ago as our most economical basic motor controllers for brushed DC motors using up to a few hundred watts. The “simple” in the name came from our trying to have fun with all the requests we had from our customers, many of whom wanted “just” this one feature. Of course, everyone wants a different feature in their minimal motor controller, so the Simple Motor Controllers actually have quite a few options, but we make it easy to set up with configuration over USB.

Status tab in the Pololu Simple Motor Control Center G2.

Input settings tab in the Pololu Simple Motor Control Center G2.

Pololu Dual G2 High-Power Motor Driver 24v18 Shield for Arduino.

Over the last few years, we have been updating our higher-power motor drivers (H-bridges with external MOSFETs) to use newer MOSFETs and MOSFET drivers, and we refer to them as our G2 high-power motor drivers. These drivers are available as small, single-channel boards, as well as dual drivers in Arduino shield and Raspberry Pi HAT form factors. Earlier this year, we brought the improved motor drivers to our Jrk G2 Motor Controllers with Feedback for those wanting to make their own closed-loop servo systems.

Now, the G2 motor driver technology is available on our Simple Motor Controllers as well. For the most part, this is not as big of a change as with the other G2 motor control products, but we did add a few nice features while maximizing backward compatibility. Key improvements over the originals include reverse voltage protection, configurable hardware current limiting, and the addition of an I²C interface for yet another control option—the others being USB, analog voltage, hobby RC servo interface, and asynchronous serial (UART). Additionally, the highest-power units (the SMC G2 18v25 and 24v19) use a four-layer board with double-sided assembly, which lets them be much smaller than their original SMC 18v25 and 24v23 counterparts:

Side-by-side comparison of the original SMC 18v25 and the newer SMC G2 18v25.

The lower-power units have the exact same size and generally have the same connector locations as the original Simple Motor Controllers:

Side-by-side comparison of the original SMC 18v15 and the newer SMC G2 18v15.

The most notable difference from a form factor and connection standpoint is the change from the USB mini-B connector on the older motor controllers to the micro-B connector on the G2 models. The following table shows the main specifications of all of the old and new Simple Motor Controllers:

Original versions, not recommended for new designs
(included for comparison purposes)
G2 versions,
released November 2018

SMC
18v7

SMC
18v15

SMC
24v12

SMC
18v25

SMC
24v23

SMC G2
18v15

SMC G2
24v12

SMC G2
18v25

SMC G2
24v19
Minimum operating voltage: 5.5 V 5.5 V 5.5 V 5.5 V 5.5 V 6.5 V 6.5 V 6.5 V 6.5 V
Recommended max
operating voltage:
24 V(1) 24 V(1) 34 V(2) 24 V(1) 34 V(2) 24 V(1) 34 V(2) 24 V(1) 34 V(2)
Max nominal
battery voltage:
18 V 18 V 28 V 18 V 28 V 18 V 28 V 18 V 28 V
Max continuous current
(no additional cooling):
7 A 15 A 12 A 25 A 23 A 15 A 12 A 25 A 19 A
USB, TTL serial,
Analog, RC control:
Yes Yes Yes Yes Yes Yes Yes Yes Yes
I²C control: Yes Yes Yes Yes
Hardware current limiting: Yes Yes Yes Yes
Reverse voltage protection: Yes Yes Yes Yes
Dimensions: 2.1″ × 1.1″ 2.3″ × 1.2″ 2.1″ × 1.1″ 1.7″ × 1.2″
Price: $39.95 $44.95 $49.95 $59.95 $64.95 $39.95 $39.95 $49.95 $49.95
Available with
connectors installed?
Yes Yes Yes No No Yes Yes No No
1 30 V absolute max.
2 40 V absolute max.

Key features of the SMC G2 family

  • Simple bidirectional control of one brushed DC motor
  • Five communication or control options:
    1. USB interface for direct connection to a PC
    2. Logic-level (TTL) serial interface for use with a microcontroller
    3. I²C interface for use with a microcontroller
    4. Hobby radio control (RC) pulse width interface for direct connection to an RC receiver or RC servo controller
    5. 0 V to 3.3 V analog voltage interface for direct connection to potentiometers and analog joysticks
  • Simple configuration and calibration over USB with a free configuration program for Windows
  • Reverse-voltage protection
  • Hardware current limiting with a configurable threshold
  • Current sensing

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

Additional features of the SMC G2 family

  • Adjustable maximum acceleration and deceleration to limit electrical and mechanical stress on the system
  • Adjustable starting speed and maximum speed
  • Option to brake or coast when speed is zero
  • Optional safety controls to avoid unexpectedly powering the motor
  • Input calibration (learning) and adjustable scaling degree for analog and RC signals
  • Under-voltage shutoff with hysteresis for use with batteries vulnerable to over-discharging (e.g. LiPo cells)
  • Adjustable over-temperature threshold and response
  • Adjustable PWM frequency from 1.13 kHz to 22.5 kHz (maximum frequency is ultrasonic, eliminating switching-induced audible motor shaft vibration)
  • Error LED linked to a digital ERR output, and connecting the error outputs of multiple controllers together optionally causes all connected controllers to shut down when any one of them experiences an error
  • Field-upgradeable firmware
  • Features of the serial, I²C, and USB interfaces:
    • Optional CRC error detection to eliminate communication errors caused by noise or software faults
    • Optional command timeout (shut off motors if communication ceases)
  • Serial features:
    • Controllable from a computer via serial commands sent to the device’s USB virtual serial (COM) port, or via TTL serial through the device’s RX/TX pins
    • TTL serial uses 0 V and 3.3 V on TX, accepts 0 V to 5 V on RX
    • Supports automatic baud rate detection from 1200 bps to 500 kbps, or can be configured to run at a fixed baud rate
    • Supports standard compact and Pololu protocols as well as the Scott Edwards Mini SSC protocol and an ASCII protocol for simple serial control from a terminal program
    • Optional serial response delay for communicating with half-duplex controllers such as the Basic Stamp
    • Controllers can be easily chained together and to other Pololu serial motor and servo controllers to control hundreds of motors using a single serial line
  • I²C features:
    • Compatible with I²C bus voltage levels from 1.8 V to 5 V
  • RC features:
    • 1/4 µs pulse measurement resolution
    • Works with RC pulse frequencies from 10 to 333 Hz
    • Configurable parameters for determining what constitutes an acceptable RC signal
    • Two RC channels allow for single-stick (mixed) motor control, making it easy to use two Simple Motor Controllers in tandem on an RC-controlled differential-drive robot
    • RC channels can be used in any mode as limit or kill switches (e.g. use an RC receiver to trigger a kill switch on your autonomous robot)
    • Battery elimination circuit (BEC) jumper can power the RC receiver with 5 V or 3.3 V
  • Analog features:
    • 0.8 mV (12-bit) measurement resolution
    • Works with 0 to 3.3 V inputs
    • Optional potentiometer/joystick disconnect detection
    • Two analog channels allow for single-stick (mixed) motor control, making it easy to use two Simple Motor Controllers in tandem on a joystick-controlled differential-drive robot
    • Analog channels can be used in any mode as limit or kill switches

As with all of our new products this year, we are offering an introductory special. Be among the first 100 customers to use coupon code SMCG2INTRO and get $10 off on up to three units (per version)!

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