Python library for the Pololu Dual G2 High-Power Motor Drivers for Raspberry Pi

Version: 2.0.0
Release Date: 2019-10-15
www.pololu.com

Summary

This library runs on the Raspberry Pi (Model B+ or newer) and provides functions for controlling both channels of the Pololu Dual G2 High-Power Motor Drivers for Raspberry Pi. This library supports both Python 2 and Python 3.

Getting Started

Installation

This library depends on pigpio, and the instructions below explain how to set it up.

These instructions assume you are using Raspbian, Debian, or some other distribution that provides the apt command for managing packages. If you do not have apt, you will need to use a different method to install the required packages.

These instructions also assume you will use Python 2. If you want to use Python 3, you will need to:

• install the python3-pigpio package instead of python-pigpio (it is okay to install both)
• use the python3 command instead of python for running Python scripts

First, to download and install pigpio and its Python module, run:

sudo apt install python-pigpio

Then, to start the pigpiod daemon, run:

sudo systemctl start pigpiod

Optionally, to automatically start the daemon every time your Raspberry Pi boots, you can also run:

sudo systemctl enable pigpiod

Finally, to download and install the dual_g2_hpmd_rpi library, run:

git clone https://github.com/pololu/dual-g2-high-power-motor-driver-rpi
cd dual-g2-high-power-motor-driver-rpi
sudo python setup.py install

Running the example program

This library comes with an example program that drives each motor in both directions. To run the example, navigate to the dual-g2-high-power-motor-driver-rpi directory and run:

python example.py

Library reference

This library uses ultrasonic 20 kHz PWM to drive the motors.

Motor speeds in this library are represented as numbers between -480 and 480 (inclusive). A speed of 0 corresponds to braking. Positive speeds correspond to current flowing from M1A/M2A to M1B/M2B, while negative speeds correspond to current flowing in the other direction.

The library can be imported into a Python program with the following line:

from dual_g2_hpmd_rpi import motors, MAX_SPEED

After importing the library, you can use the functions below to enable the motors and set motor speeds:

• motors.enable(): Enable both motor 1 and motor 2.
• motors.motor1.enable(): Enable motor 1.
• motors.motor2.enable(): Enable motor 2.
• motors.disable(): Disable both motor 1 and motor 2.
• motors.motor1.disable(): Disable motor 1.
• motors.motor2.disable(): Disable motor 2.
• motors.setSpeeds(m1_speed, m2_speed): Set speed and direction for both motor 1 and motor 2.
• motors.motor1.setSpeed(speed): Set speed and direction for motor 1.
• motors.motor2.setSpeed(speed): Set speed and direction for motor 2.
• motors.getFaults(): Returns True if there is a fault on either motor driver, False if no fault.
• motors.motor1.getFault(): Returns True if there is a fault on motor driver 1, False if no fault.
• motors.motor2.getFault(): Returns True if there is a fault on motor driver 2, False if no fault.

For convenience, a constant called MAX_SPEED (which is equal to 480) is available on all the objects provided by this library. You can access it directly by just writing MAX_SPEED if you imported it as shown above, or it can be accessed in the following ways:

• motors.MAX_SPEED
• motors.motor1.MAX_SPEED
• motors.motor2.MAX_SPEED

If you are controlling multiple motor drivers, you might prefer to import the library using import dual_g2_hpmd_rpi, which requires the commands listed above to be prefixed with dual_g2_hpmd_rpi..

Version history

• 2.0.0 (2019-10-15): Changed interface library from WiringPi to pigpio. Added functions for reading driver faults and updated example.
• 1.0.0 (2017-11-16): Original release.