High-Power Simple Motor Controller G2 18v25

Tech Tips:

User Manual

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

• USB features:
  • Full-speed USB interface (12 Mbps)
  • Example code in C#, Visual Basic .NET, and Visual C++ is available in the Pololu USB Software Development Kit

• 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

Video Demo

Pololu Simple Motor Controller and Sharp Analog Distance Sensor Demonstration - This video demonstrates the versatility of the Simple Motor Controller by showing how it can be controlled directly from the analog output of a Sharp analog distance sensor—there is no intermediate control board and no programming involved. The unit in the video is one of Pololu's original SMCs, but the newer SMC G2s have the same capabilities. For more information on this example, including the SMC settings file and a list of parts used, see blog post about the demo.

Comparison to the original Simple Motor Controllers

The SMC G2 family features a number of improvements compared to Pololu's original Simple Motor Controllers with green PCBs:

• Reverse voltage protection
• Configurable hardware current limiting – the motor drivers on the SMC G2 use current chopping to actively limit the motor current when it exceeds a software-configurable threshold
• I²C interface provides an additional control option
• USB Micro-B connector (instead of Mini-B as on the original SMCs)
• The SMC G2 18v25 and 24v19 use a four-layer board with double-sided assembly, which lets them be much smaller than their original counterparts (the SMC 18v25 and 24v23)

The SMC G2 controllers have the same pin arrangements as the original SMCs, so they should be usable as drop-in replacements in typical applications, though note that the minimum operating voltage is a little higher for the G2 versions (6.5 V vs 5.5 V for the originals). The SMC G2 serial protocol is compatible with (and generally a superset of) the original SMC serial protocol, so in most cases, serial interface software running on a microcontroller or computer will not need to be modified to work with a SMC G2.