Question

Develop a program using python to demonstrate data exchange using USB protocol.

Answer 1

To do such communication , we have to use Python library.
We will use pyusb for this. Below is the commnad to install it.

pip install --user pyusb

usb.core is the main part of pyusb. Most of the programs starts by importing it. 

Below is the working command as question doesn't describe with which product USB should be workign. 

#!/usr/bin/env python2

# Send a BEEP command via USB to a Lego Mindstorms EV3 brick

import sys
import usb.core                 # https://walac.github.io/pyusb/

def ev3_write(command):
    # To send commands, we need an Endpoint.

    # To get to the endpoint we need to descend down the hierarchy of
    # 1. Device
    VENDOR_LEGO = 0x0694
    PRODUCT_EV3 = 5
    # 2. Configuration 
    CONFIGURATION_EV3 = 1       # 1-based
    # 3. Interface
    INTERFACE_EV3 = 0           # 0-based
    # 4. Alternate setting
    SETTING_EV3 = 0             # 0-based
    # 5. Endpoint
    ENDPOINT_EV3 = 1            # 0-based

    # 1. Device
    device = usb.core.find(idVendor=VENDOR_LEGO, idProduct=PRODUCT_EV3)
    if device is None:
        print("Is the brick connected and turned on?")
        sys.exit(1)

    # By default, the kernel will claim the device and make it available via
    # /dev/usb/hiddevN and /dev/hidrawN which also prevents us
    # from communicating otherwise. This removes these kernel devices.
    # Yes, it is weird to specify an interface before we get to a configuration.
    if device.is_kernel_driver_active(INTERFACE_EV3):
        print("Detaching kernel driver")
        device.detach_kernel_driver(INTERFACE_EV3)

    # 2. Configuration
    # A Device may have multiple Configurations, and only one can be active at
    # a time. Most devices have only one. Supporting multiple Configurations
    # is reportedly useful for offering more/less features when more/less
    # power is available.
    ## Because multiple configs are rare, the library allows to omit this:
    ## device.set_configuration(CONFIGURATION_EV3)
    configuration = device.get_active_configuration()

    # 3. Interface
    # A physical Device may have multiple Interfaces active at a time.
    # A typical example is a scanner-printer combo.
    #
    # 4. Alternate setting
    # I don't quite understand this, but they say that if you need Isochronous
    # Endpoints (read: audio or video), you must go to a non-primary
    # Alternate Setting.
    interface = configuration[(INTERFACE_EV3, SETTING_EV3)]

    # 5. Endpoint
    # The Endpoint 0 is reserved for control functions
    # so we use Endpoint 1 here.
    # If an Interface uses multiple Endpoints, they will differ
    # in transfer modes:
    # - Interrupt transfers (keyboard): data arrives soon, with error detection
    # - Isochronous transfers (camera): data arrives on time, or gets lost
    # - Bulk transfers (printer): all data arrives, sooner or later
    endpoint = interface[ENDPOINT_EV3]

    # Finally!
    endpoint.write(command)

beep_command = \
    '\x0F\x00\x01\x00\x80\x00\x00\x94\x01\x81\x02\x82\xE8\x03\x82\xE8\x03'
ev3_write(beep_command)

Above program is taken from : http://mvidner.blogspot.com/2017/01/usb-communication-with-python-and-pyusb.html