libftdi Archives

Subject: usb bulk write fails

From: Newell Jensen <Newell.Jensen@xxxxxxxxx>
To: libftdi@xxxxxxxxxxxxxxxxxxxxxxx
Date: Sun, 7 Nov 2010 19:27:59 -0800

I am using the python-ftdi package in Ubuntu 10.10 (64-bit) for a FT4232H mini module and I am running into problems and hope that someone could help me out here.

1. The first issue I am running into is when I go to set the clock divisor.  Since this is an FT432H chip I disable the 5X divide by issuing the command:

import ftdi
ftdic = ftdi.ftdi_context()

>>> ftdi.ftdi_write_data(ftdic, chr(0x8a), 1)
which gives back a 1, which is what I would expect.  However, after setting this and doing (with div equal to 0 since I want the fastest clock frequency):

>>> 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)

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?

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.


Newell Jensen

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