Python-puzzled

[Mike Butts]

Hi Chris and FPGAlinkers,

Last weekend I learned Python, translated a simple assembler I wrote for my FPGA CPU from Java to Python, and was delighted with how quickly that went. Python often seems to have just what I would like, and the interactive mode makes it so easy to work out questions. So now I'm translating my FPGAlink-based runtime monitor from C to Python. That's going pretty well but getting started I ran into a puzzling problem.

I did the interactive execution Chris included in examples/python/README, in a form to suit my Mac (DYLD_LIBRARY_PATH) and my Atlys board (1443:0007). That worked just fine, and lit up the LED on my board.

But when I put the very same statements into a script and run it, flOpen failed. See my transcript below: first the script, then the interactive session, then executing the script.

I must be missing something here. Any ideas? Thanks!

  --Mike

PS: Chris, I'm so into Python I haven't tried out your new Java binding. Hope you don't mind. Everything you've created and the support you're giving users is just above and beyond, thanks.

--
Mike Butts mbu...@ieee.org

MBMBPro:software mike$ more foo.py 

#!/usr/bin/python

#

from fpgalink2 import *

flLoadStandardFirmware("1443:0007", "1443:0007", "D0234")                # 1443:0007 for Nexys3 & Atlys

handle = flOpen("1443:0007")                                             # Open the connection

flPlayXSVF(handle, "libfpgalink-20120621/gen_csvf/ex_cksum_atlys_fx2_verilog.csvf")  # Or other SVF, XSVF or CSVF

flWriteChannel(handle, 1000, 0x00, 0x10)                                 # Write a byte to channel 0

flClose(handle)

MBMBPro:software mike$ python

Python 2.6.1 (r261:67515, Aug  2 2010, 20:10:18) 

[GCC 4.2.1 (Apple Inc. build 5646)] on darwin

Type "help", "copyright", "credits" or "license" for more information.

>>> from fpgalink2 import *

>>> flLoadStandardFirmware("1443:0007", "1443:0007", "D0234")

>>> handle = flOpen("1443:0007") 

>>> flPlayXSVF(handle, "libfpgalink-20120621/gen_csvf/ex_cksum_atlys_fx2_verilog.csvf")

>>> flWriteChannel(handle, 1000, 0x00, 0x10) 

>>> flClose(handle)

>>> ^D

MBMBPro:software mike$ python foo.py 

Traceback (most recent call last):

  File "foo.py", line 5, in <module>

    handle = flOpen("1443:0007")                                             # Open the connection

  File "/Users/mike/ComputeForest/software/fpgalink2.py", line 112, in flOpen

    raise FLException(s)

fpgalink2.FLException: flOpen(): Device 1443:0007 not found

MBMBPro:software mike$ 

[Mike Butts]

It's a race. If I copy the contents of my script and paste them into the python command line, it fails the same way as the script does. But when I copy/paste a line at a time it works fine.

That told me there's some sort of race here, that running flOpen immediately after flLoadStandardFirmware fails, but with manual delay it works fine. So I added time.sleep() between them in my script. With a 1 second delay it fails, but with a 2 second delay it works.

There must be something my code should check after flLoadStandardFirmware and before flOpen, to synchronize properly???

Thanks again!

  --Mike

#!/usr/bin/python

#

from fpgalink2 import *

import time

status = flLoadStandardFirmware("1443:0007", "1443:0007", "D0234")                # 1443:0007 for Nexys3 & Atlys

print "sleep"

time.sleep(2)

print "awake"

handle = flOpen("1443:0007")                                             # Open the connection

flPlayXSVF(handle, "libfpgalink-20120621/gen_csvf/ex_cksum_atlys_fx2_verilog.csvf")  # Or other SVF, XSVF or CSVF

flWriteChannel(handle, 1000, 0x00, 0x10)                                 # Write a byte to channel 0

flClose(handle)

[Chris McClelland]

This is what flAwaitDevice()[1] is for. The fpgalink2.py itself may be
executed directly; it includes an example of flAwaitDevice() usage[2].

The timeout is in tenths of a second*. The firmware renumeration delay
will be about 1500ms[3], so unless there's something very wrong with the
OS itself, renumeration should happen within a couple of seconds.

Chris

[1]https://github.com/makestuff/libfpgalink/blob/master/examples/python/fpgalink2.py#L121
[2]https://github.com/makestuff/libfpgalink/blob/master/examples/python/fpgalink2.py#L338
[3]https://github.com/mulicheng/fx2lib/blob/master/include/fx2macros.h#L99

* Actually there's an extra 1s delay inserted initially. This is because
it's legal to set the target VID:PID to be the same as the initial
VID:PID. It wouldn't do to have flAwaitDevice() respond immediately with
"yup, it's there!" before the FX2LP has had a chance to drop off the
bus.

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[Peter Stuge]

Chris McClelland wrote:
> it's legal to set the target VID:PID to be the same as the initial VID:PID.

Actually that is quite questionable USB behavior.

> It wouldn't do to have flAwaitDevice() respond immediately

libusb is getting a hotplug API. Hang in there.


//Peter

[Mike Butts]

Yes! That does the trick. I should have read fpgalink2.py more closely. Thank you!

  --Mike

--
Mike Butts mbu...@ieee.org

[Soumitra khair]

Chris and libfpgalink users

I am using Nexys3 board and python.

In my python script I am having issues in connecting to FPGA . In my script I have tried to connect using the code from flici.

def fpga():
    handle = fl.FLHandle()

    try:
        fl.flInitialise(0)

        vp = "1443:0007"
        print("Attempting to open connection to FPGALink device {}...".format(vp))
        try:
            handle = fl.flOpen(vp)
        except fl.FLException as ex:
            if True:
                ivp = "1443:0007"
                print("Loading firmware into {}...".format(ivp))
                fl.flLoadStandardFirmware(ivp, vp)

                print("Awaiting renumeration...")
                if (not fl.flAwaitDevice(vp, 600)):
                    raise fl.FLException("FPGALink device did not renumerate properly as {}".format(vp))

                print("Attempting to open connection to FPGALink device {} again...".format(vp))
                handle = fl.flOpen(vp)
            else:
                raise fl.FLException("Could not open FPGALink device at {} and no initial VID:PID was supplied".format(vp))

        isNeroCapable = fl.flIsNeroCapable(handle)


    except fl.FLException as ex:
        print(ex)
    finally:
        fl.flClose(handle)
        print("Exit Finally")

Following output I am getting when I am calling fpga() for connecting to fpga

Attempting to open connection to FPGALink device 1443:0007...

Loading firmware into 1443:0007...

Awaiting renumeration...

FPGALink device did not renumerate properly as 1443:0007

Exit Finally

Although when I am connecting to FPGA in commadline mode its working.Am I missing something in this code ?

Thanks,

SK

[Chris McClelland]

Start from a known-good state. Fetch and build the latest release (20170708) and try the appropriate command from the "noninteractive execution" section of the examples/python/README[1]. In your reply, show exactly what command you ran, and exactly what response you get.

Chris

[1]https://github.com/makestuff/libfpgalink/tree/20170708/examples/python/README

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