libftdi Archives

Subject: Re: usb bulk write fails

From: Thomas Jarosch <thomas.jarosch@xxxxxxxxxxxxx>
To: libftdi@xxxxxxxxxxxxxxxxxxxxxxx
Date: Wed, 17 Nov 2010 20:49:40 +0100
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??


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