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A library for controlling a Pololu VNH5019 Motor Controller Shield via USB Serial and I2C.

Project description

VNH5019Controller Python Library

This library provides the Controller class to generate valid messages and communicate with the motor controller via either I2C or USB. Before any commands can be sent, the functions init_serial() or init_i2c() must be called. The constants CHANNEL_1, CHANNEL_2, and BOTH are passed to Controller.write_speed() and Controller.write_brake() to select the appropriate channel.

Installation

pip install VNH5019-Serial-Controller

Classes:

Controller

A class for writing to the VNH5019 Motor Controller via either I2C or USB.

Constants:

CHANNEL_1

CHANNEL_2

BOTH

Functions:

init_serial( port_name )

Initialize a serial port for communication with the motor controller.

port_name

Type: string

The name of the serial port to communicate over.

Returns

Type: None

init_i2c( pre_existing_bus=None )

Initialize the serial bus for communication.

pre_existing_bus

Type: SMBus

Default: None

A pre-existing I2C bus if it exists.

Returns

Type: None

Controller Methods

write_speed( channel, value )

Write a speed value between -100 (full reverse) to 100 (full forward) to one or both channels.

channel

Type: int

The channel whose speed we want to set. Must be one of CHANNEL_1, CHANNEL_2, or BOTH.

value

Type: int

The speed we want to set between -100 to 100.

Returns

Type: None

write_brake( channel, value )

Write a brake value between 0 (coast) to 100 (max brake) to one or both channels.

channel

Type: int

The channel whose speed we want to set. Must be one of CHANNEL_1, CHANNEL_2, or BOTH.

value

Type: int

The brake we want to set between 0 to 100.

Returns

Type: None

write_mixed_command( speed_val, turn_val )

Write a mixed command to the motor controller.

speed_val

Type: int

The speed we want to write between -100 (full reverse) to 100 (full forward).

turn_val

Type: int

The turn value we want to write between -100 (max left) to 100 (max right).

Returns

Type: None

stop()

Stop both motors by applying max brakes.

Returns

Type: None

set_active()

Put the motor controller into an active state.

Returns

Type: None

set_standby()

Put the motor controller into standby.

Returns

Type: None

Example

import VNH5019Controller
from time import sleep
from sys import argv

controller = VNH5019Controller.Controller()


def setup():
    print("Setting Up...")
    VNH5019Controller.init_serial(argv[1])
    sleep(5)
    controller.set_active()
    sleep(2)
    print("Ready!")


def loop():
    while True:
        # Drive Forward
        print("Forward")
        controller.write_speed(VNH5019Controller.BOTH, 100)
        sleep(1)
        controller.stop()
        sleep(1)

        # Drive Backward
        print("Backward")
        controller.write_speed(VNH5019Controller.BOTH, -100)
        sleep(1)
        controller.stop()
        sleep(1)

        # Turn Left Forward
        print("Forward Left")
        controller.write_mixed_command(100, -50)
        sleep(1)
        controller.stop()
        sleep(1)

        # Turn Right Forward
        print("Forward Right")
        controller.write_mixed_command(100, 50)
        sleep(1)
        controller.stop()
        sleep(1)

        # Turn Left Backward
        print("Backward Left")
        controller.write_mixed_command(-100, -50)
        sleep(1)
        controller.stop()
        sleep(1)

        # Turn Right Backward
        print("Backward Right")
        controller.write_mixed_command(-100, 50)
        sleep(1)
        controller.stop()
        sleep(1)

        # Enter Standby
        print("Entering Standby...")
        controller.set_standby()
        sleep(5)

        # Enter Active
        print("Entering Active...")
        controller.set_active()
        sleep(2)


def main():
    setup()
    loop()


if __name__ == '__main__':
    main()

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