Re: usb bulk write fails

[Newell Jensen <Newell.Jensen@xxxxxxxxx>]

Thomas,

Thanks for the reply. �So I researched it some more, both with Python and C programs which give the same response. �I have posted my Python script here�http://pastebin.com/k7PuLsQq�and for the C program I just used the libftdispi at�http://code.google.com/p/libftdispi/�and I have several things that I would like to point out:

1. If I only try to claim INTERFACE_A, then I get usb_bulk_write fails (no new message shown with dmesg) and program execution does not complete.

2. If I try to claim other interfaces besides INTERFACE_A, usb_bulk_write works and the program completes execution but I get a message in dmesg that says this:

[ 1129.201072] usb 2-6: usbfs: process 13739 (spitest) did not claim interface 1 before use

3. If I try to claim interfaces A-D (I have the FT4232), then the same thing happens as in 2 above where I get program to complete execution and a new message in dmesg is shown. �This leads me to believe that INTERFACE_A is claimed here?

So here is my question ...�Does the dmesg message as talked about in 2 above a concern? �Or is this normal behavior?

I haven't gotten far enough yet to test whether I do actually have control over all the interfaces and that is my next step but if you see anything of concern, let me know.

Thanks!

On Wed, Nov 17, 2010 at 11:49 AM, Thomas Jarosch <thomas.jarosch@xxxxxxxxxxxxx> wrote:

Hello Newell,

On 11/08/2010 04:27 AM, Newell Jensen wrote:
>>>> buf0 = chr(ftdi.TCK_DIVISOR) # command "set divisor"
>>>> buf1 = chr(div & 0xFF) �# NOTE: I have also tried using chr((div >> 0) & 0xFF) as well
>>>> buf2 = chr(((div >> 8) & 0xFF))
>>>> buf = buf0 + buf1 + buf2
>>>> ftdi.ftdi_write_data(ftdic, buf, 3)
> -110
>
> So that is one issue I run into. �That is, where the disabling of the 5X works but the other clock divisor setting doesn't. �Something interesting is if I do the above without disabling the 5X, then it works. �Any ideas on this?

Hmm. No idea right now. Could you come up
with a small C example code to demonstrate the issue?

> 2. The second issue I run into is setting the loopback after setting the clock divisor above (so I am not disabling the 5X so that I proceed on in my script to the loopback setting). �When I go to disable or enable the loopback I get usb bulk write fail from the command below:
>
>>>> ftdi.ftdi_write_data(ftdic, chr(ftdi.LOOPBACK_START), 1)
>
>
> Any help would be greatly appreciated as at this point I am just scratching my head.

Never used that either. Though I'm not sure
if the ftdi.ftdi_write_data is the correct function
when using the python wrapper: ftdi_write_data() calls
usb_bulk_write(). Configuration changes inside
libftdi are normally communicated via usb_control_msg()
and also feature different "requests". Not sure
how you emulated that via the python wrapper??

Cheers,
Thomas

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