Python library for the Pololu DRV8835 Dual Motor Driver Kit for Raspberry Pi
Release Date: 2016-05-04
This library runs on the Raspberry Pi (Model B+, A+, Pi 2, or Pi 3) and provides functions for controlling both channels of the Pololu DRV8835 Dual Motor Driver Kit for Raspberry Pi. This library supports both Python 2 and Python 3.
Programs that use this library will need to be run as the root user so they can access the GPIO pins.
These instructions assume you are using Raspbian, Debian, or some other distribution that provides the
apt-get command for managing packages. If you do not have
apt-get, 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 replace
python3 in the names of the
apt-get packages below, and use the
python3 command instead of
python for running Python scripts, and use the
pip3 command instead of
pip to install pip packages.
First, to download and install WiringPi-Python, run:
sudo apt-get install python-dev python-pip sudo pip install wiringpi
Finally, to download and install the pololu_drv8835_rpi library, run:
git clone https://github.com/pololu/drv8835-motor-driver-rpi.git cd drv8835-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 drv8835-motor-driver-rpi directory and run:
sudo python example.py
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 pololu_drv8835_rpi import motors, MAX_SPEED
After importing the library, you can use the commands below to set motor speeds:
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.
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:
If you are controlling multiple motor drivers, you might prefer to import the library using
import pololu_drv8835_rpi, which requires the commands listed above to be prefixed with