db4fd99309
The old method only worked out of the box if you were running Python 2.1 on a 586. I imagine that is too small a slice of current users to be worth hard coding ;).
150 lines
4.7 KiB
Python
Executable file
150 lines
4.7 KiB
Python
Executable file
#!/usr/bin/env python
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## It emulates the program "cmd" which is distributed with
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## the comedilib software
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## Copyright (C) May 2003 Luc Lefebvre <luc.lefebvre@mcgill.ca>
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## Mar 2012 W. Trevor King <wking@drexel.edu>
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##
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## This program is free software; you can redistribute it and/or
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## modify it under the terms of the GNU General Public License
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## as published by the Free Software Foundation; either version 2
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## of the License, or (at your option) any later version.
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## This program is distributed in the hope that it will be useful,
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## but WITHOUT ANY WARRANTY; without even the implied warranty of
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## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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## GNU General Public License for more details.
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#set the paths so python can find the comedi module
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import sys, os, string, struct, time
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import comedi as c
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#open a comedi device
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dev=c.comedi_open('/dev/comedi0')
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if not dev: raise "Error openning Comedi device"
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#get a file-descriptor for use later
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fd = c.comedi_fileno(dev)
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if fd<=0: raise "Error obtaining Comedi device file descriptor"
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BUFSZ = 10000
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freq=1000 # as defined in demo/common.c
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subdevice=0 #as defined in demo/common.c
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nscans=8000 #specify total number of scans
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#three lists containing the chans, gains and referencing
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#the lists must all have the same length
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chans=[0,1,2,3]
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gains=[0,0,0,0]
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aref =[c.AREF_GROUND, c.AREF_GROUND, c.AREF_GROUND, c.AREF_GROUND]
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cmdtest_messages = [
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"success",
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"invalid source",
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"source conflict",
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"invalid argument",
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"argument conflict",
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"invalid chanlist"]
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nchans = len(chans) #number of channels
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#wrappers include a "chanlist" object (just an Unsigned Int array) for holding the chanlist information
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mylist = c.chanlist(nchans) #create a chanlist of length nchans
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#now pack the channel, gain and reference information into the chanlist object
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#N.B. the CR_PACK and other comedi macros are now python functions
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for index in range(nchans):
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mylist[index]=c.cr_pack(chans[index], gains[index], aref[index])
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def dump_cmd(cmd):
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print "---------------------------"
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print "command structure contains:"
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print "cmd.subdev : ", cmd.subdev
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print "cmd.flags : ", cmd.flags
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print "cmd.start :\t", cmd.start_src, "\t", cmd.start_arg
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print "cmd.scan_beg :\t", cmd.scan_begin_src, "\t", cmd.scan_begin_arg
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print "cmd.convert :\t", cmd.convert_src, "\t", cmd.convert_arg
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print "cmd.scan_end :\t", cmd.scan_end_src, "\t", cmd.scan_end_arg
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print "cmd.stop :\t", cmd.stop_src, "\t", cmd.stop_arg
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print "cmd.chanlist : ", cmd.chanlist
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print "cmd.chanlist_len : ", cmd.chanlist_len
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print "cmd.data : ", cmd.data
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print "cmd.data_len : ", cmd.data_len
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print "---------------------------"
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## ret = c.comedi_get_buffer_size(dev, subdevice)
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## if ret==-1:
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## raise "Error fetching comedi buffer size"
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## else:
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## print "buffer size = ", ret
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## ret = c.comedi_get_max_buffer_size(dev, subdevice)
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## if ret==-1:
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## raise "Error fetching comedi max buff size"
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## else:
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## print "max buff size = ", ret
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#construct a comedi command
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cmd = c.comedi_cmd_struct()
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period = int(1.0e9/freq) # in nanoseconds
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ret = c.comedi_get_cmd_generic_timed(dev,subdevice,cmd,nchans,period)
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if ret: raise "Error comedi_get_cmd_generic failed"
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cmd.chanlist = mylist # adjust for our particular context
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cmd.chanlist_len = nchans
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cmd.scan_end_arg = nchans
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if cmd.stop_src==c.TRIG_COUNT: cmd.stop_arg=nscans
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print "command before testing"
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dump_cmd(cmd)
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#test our comedi command a few times.
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ret = c.comedi_command_test(dev,cmd)
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print "first cmd test returns ", ret, cmdtest_messages[ret]
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if ret<0: raise "comedi_command_test failed"
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dump_cmd(cmd)
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ret = c.comedi_command_test(dev,cmd)
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print "second test returns ", ret, cmdtest_messages[ret]
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if ret<0: raise "comedi_command_test failed"
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if ret !=0:
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dump_cmd(cmd)
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raise "Error preparing command"
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#execute the command!
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## ret = c.comedi_command(dev,cmd)
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## if ret !=0: raise "comedi_command failed..."
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datastr = ()
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t0 = time.time()
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ret = c.comedi_command(dev,cmd)
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if ret !=0: raise "comedi_command failed..."
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while (1):
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#ret = c.comedi_poll(dev,subdevice)
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#print "poll ret = ", ret
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data = os.read(fd,BUFSZ)
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#print "len(data) = ", len(data)
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if len(data)==0:
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break
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n = len(data)/2 # 2 bytes per 'H'
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format = `n`+'H'
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#print "format = ", format
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#bytes = struct.calcsize(format)
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#print "bytes = ", bytes
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#nbytes = c.comedi_get_buffer_contents(dev,subdevice)
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#print "n = ", n, " nbytes = ", nbytes
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datastr = datastr + struct.unpack(format,data)
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t1 = time.time()
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print "start time : ", t0
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print "end time : ", t1
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print "time : ", t1 - t0, " seconds"
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count = 0
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while count < len(datastr):
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for i in range(4):
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print "%d\t" % datastr[count+i],
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print "\n"
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count = count + 4
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ret = c.comedi_close(dev)
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if ret !=0: raise "comedi_close failed..."
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