[avrdude-dev] avrrftdi driver port selection

[Jonathan Schneider]

I am trying to use avrdude 5.11.1 on i386 Linux (Ubuntu 12.04) with an FT2232D 
wired tp an AT90S2313 in accordance with FTDI’s MPSSE application note AN_135 
(which in summary says pins 23->MOSI, 22->MISO, 24->SCK, 21->nRESET).

But I am absolutely baffled as to what port to specify.

I know to use -p avrftdi -p 2313 and be the superuser (until sensible 
permissions can be assigned anyway).

If I put usb:999 or even complete garbage after the -P I don’t get any kind of 
meaningful error but does seem to know whether I have the FT2232D plugged in 
regardless of -P. It looks as if port selection is somehow completely automatic 
and -P is ignored. What if I have more than one FT2232D ?

I cannot find clear documentation on how to specify the port for accessing this 
kind of device beyond a mention of usb:N which doesn’t seem to do anything. 
Maybe I have failed to find the right documentation.

There is a reasonable chance the hardware has a silly mistake as last night was 
a late one but I would like to know I’ve got the software end right as well so 
would appreciate some input (and improved documentation for the next person).

Thank you,

Jon