MCP2200 USB HID interfacing test.py

#!/usr/bin/python3
##
## Interfacing with the MCP2200 GPIO via USB HID. Plays with the first four GPIO ports.
##
## Used for controlling 4 port USB relay board from Denkovi.
##
import usb.core
import usb.util
import time

## find it
dev = usb.core.find(idVendor = 0x04d8, idProduct = 0x00df)

if dev is None:
        print('Not found')
else:
        print('Found')

## set the endpoint (output)
endpoint = dev[0][(2,0)][1]

## claim the device from the kernel
try:
        if dev.is_kernel_driver_active(2):
                dev.detach_kernel_driver(2)

        usb.util.claim_interface(dev, 2)
        print('Claimed device')
## if it fails, give it back
except:
        usb.util.release_interface(dev, 2)
        if not dev.is_kernel_driver_active(2):
                dev.attach_kernel_driver(2)

        print('Returned device')

## set device parameters (GPIOs are outputs, default off, etc)
## see http://ww1.microchip.com/downloads/en/DeviceDoc/93066A.pdf
print('Configuring device')
data = [0]*16
data[0] = 0x10
dev.write(endpoint.bEndpointAddress, data)

data = [0]*16
data[0] = 0x08 ## command

while True:
        ## everything off
        data[11] = 0x00
        data[12] = 0xFF
        dev.write(endpoint.bEndpointAddress, data)
        print('All off')
        time.sleep(1)

        ## cycle through the outputs, turning them on one by one
        data[12] = 0x00
        data[11] = 0x01
        dev.write(endpoint.bEndpointAddress, data)
        print('Output one')
        time.sleep(0.25)
        data[11] = 0x02
        dev.write(endpoint.bEndpointAddress, data)
        print('Output two')
        time.sleep(0.25)
        data[11] = 0x04
        dev.write(endpoint.bEndpointAddress, data)
        print('Output three')
        time.sleep(0.25)
        data[11] = 0x08
        dev.write(endpoint.bEndpointAddress, data)
        print('Output four')
        time.sleep(1)

        ## then turn two and four off
        data[11] = 0x00
        data[12] = 0x0A
        print('Two+four off')
        dev.write(endpoint.bEndpointAddress, data)
        time.sleep(1)