I've written an experimental driver for Alteras USB
Blaster cable and published it as a patch to current
CVS version of openwince-jtag on
To access the cable, a new parallel port driver "ftdi"
had to be added, based on libftdi (I tested with
libftdi-dev 0.6 that comes with Debian Sarge).
You can connect it like
cable ftdi * UsbBlaster
But beware, it is VERY slow (100x slower than
ByteBlaster driver): "detect" with a single EP1C12 in
the chain takes 17 seconds (as opposed to 0.17 s with
ByteBlaster). This is probably due to the fact that
bit banging over USB has a much higher overhead than
with a directly attached parallel port. However, I
tried to circumvent this by adding a "transfer()"
function that accumulates several bit changes into a
single transfer for the USB Blaster. There may well be
some flaw in the code that puts the brake on the transfers.
The addition of transfer() affects every cable driver,
but adding it is as easy as adding "generic_transfer"
in your cable_driver_t. I even noticed a slight speedup
with the byteblaster driver after adding
I won't spend too much more time on this driver, as I'm
not really sure whether using this adapter in an
application designed for direct parallel port access is
the right way to go (and I'm not sure whether
openwince-jtag is still alive anyway?!).