#! /usr/bin/env mpscript
#
#  This script tests USB access by reading the current position from a
#  USB motor controller from Phidgets, Inc.  The script assumes that the
#  Phidget controller has already had its firmware uploaded.  Running the
#  test script 'mphidget' found in the 'test' directory of the main MX
#  package is sufficient to do that.  However, if the MX test script
#  'mphidget' is still running when you invoke the current script, the
#  find_device_by_order() method will fail, since the device is already
#  in use by the 'mphidget' script.
#
#  Since this script accesses USB devices that are not handled by 'hotplug',
#  it is necessary to run this script as 'root' on Linux.
#

import struct

def main( record_list, argv ):

	libusb = record_list.get_record( 'libusb' )

	phidget = libusb.find_device_by_order( 0x6c2, 0x46, 0, 1, 0, 0, 0 )

	status_string = phidget.bulk_read( 0x82, 16, 1.0 )

	unpack_format = "%iB" % len( status_string )

	status_tuple = struct.unpack( unpack_format, status_string )

	m1_position = status_tuple[0] + ( status_tuple[1] << 8 ) \
			+ ( status_tuple[2] << 16 ) + ( status_tuple[3] << 24 )

	m2_position = status_tuple[4] + ( status_tuple[5] << 8 ) \
			+ ( status_tuple[6] << 16 ) + ( status_tuple[7] << 24 )


	print "m1 = %i, m2 = %i" % ( m1_position, m2_position )