#!/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("CH1:SCALE?")
    vscale = float(u.read(1).split()[1])
    print("Channel 1 scale is %.2f volts/div" % (vscale))
    u.write("HOR:MAIN:SCALE?")
    hscale = float(u.read(1).split()[1])
    print("Horizontal scale is %f sec/div" % (hscale))

    u.write("*WAI")		# Make sure the previous commands have been
                                # executed
    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 (should verify this really..)
    dattype = numpy.dtype('>h')	# Big endian 16 bit quantity
    ary = numpy.fromstring(data, dtype = dattype)
    ary = ary / 32768.0 * vscale
    pylab.plot(ary)
    pylab.show()
    
if __name__ == "__main__":
    main()