#!/usr/bin/env python

# Copyright (c) 2009
#      Daniel O'Connor <darius@dons.net.au>.  All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
# 1. Redistributions of source code must retain the above copyright
#    notice, this list of conditions and the following disclaimer.
# 2. Redistributions in binary form must reproduce the above copyright
#    notice, this list of conditions and the following disclaimer in the
#    documentation and/or other materials provided with the distribution.
#
# THIS SOFTWARE IS PROVIDED BY AUTHOR AND CONTRIBUTORS ``AS IS'' AND
# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED.  IN NO EVENT SHALL AUTHOR OR CONTRIBUTORS BE LIABLE
# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
# OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
# HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
# OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
# SUCH DAMAGE.
#

import usb488
import matplotlib.pylab as pylab
import numpy
import time

def main():
    u = usb488.USB488Device()
    print "Found device"

    u.write("*IDN?")
    print "IDN reports " + u.read()
    
    u.write("DATA:ENC RIB")	# Big endian signed
    u.write("DATA:WIDTH 2")	# 2 bytes wide
    u.write("SELECT:CH1 ON")	# Turn channel 1 on
    u.write("DATA:SOURCE CH1")	# Set the curve source to channel 1
    u.write("CURVE?")		# Ask for the curve data
    then = time.time()                            
    result = u.read(1.0)	# Takes the CRO a while for this
    now = time.time()
    print "CURVE read took %f milliseconds" % ((now - then) * 1000.0)
    data = result[13:]		# Chop off the header
    dattype = numpy.dtype('>h')	# Big endian 16 bit quantity
    ary = numpy.fromstring(data, dtype = dattype)
    pylab.plot(ary)
    pylab.show()
    
if __name__ == "__main__":
    main()