Ro Ro , Aug 05, 2004; 12:17 p.m.
Does anyone have detailed information about the lens protocol used in
old Nikkor AF and AI-P lenses?
I wonder if it should not be impossible to make custom chips by using
a 1$ PIC12C508 or similar. Open source preferred.
Why that? Nikon doesn't sell chips to everyone, and they are
expensive. Chips from old lenses don't often fit the apertures of the
manual lens to be upgraded. An MF lens with an AF chip makes the
Camera try to AF, not so good. Even if you find a chip with suiting
apertures, the focal length is different.
Thats what I found out myself:
The names of the lens contacts could be found in some old service
manuals that can be download on the internet. Search for 'n90.pdf'
with google.
I recently dissassembled an old Nikkor 35-70/3.3-4.5 to see whats
inside. The only important thing is a NEC uPD7554G577. The datasheet
was hard to find, but I now have one, which I could mail to anyone
who's interested.
The NEC CPU is an old and slow 4-bit one, so the protocol can't be
that complicated.
I drew a sipmle schematic to show the connections.
But I don't have a logic-analyzer to figure out what data is
transmitted. Could anyone help?
Schematic Nikkor 35-70/3.3-4.5
Ro Ro , Aug 05, 2004; 02:15 p.m.
Zack Lau , Aug 05, 2004; 02:25 p.m.
http://www.xs4all.nl/~jwasys/old/diy2.html
A link to a do it yourself logic analyzer that uses a PC parallel port.
Shakil K. , Aug 05, 2004; 05:00 p.m.
Hi Ro Ro,
I can't help you on this, but whatever result you get (doesn't matter how long it takes), please let us know the final version by posting it here/in a new thread. Thanks,
Shakil
Ro Ro , Aug 05, 2004; 05:40 p.m.
This analyzer software works great ;) I had to use the allowio driver with w2k ('allowio DIGITRACE.EXE' in the command prompt). The buffer was increased to 255000.
I build a simple buffer with a 74LS14 to protect the camera (Nikon N4004s)
lens --|>o--|>o-- lpt
Many byte flying on the lines but slow enough to get cought. The screenshot shows the beginning of transfer.
I'm busy the next days but will try to figure more out next week. The datasheet schuld tell about the bitorder.
Perhaps someone else who likes experiments could try the same.
Ro Ro , Aug 05, 2004; 05:41 p.m.
Sorry, I forgot the picture
Walter Schroeder , Aug 06, 2004; 06:29 a.m.
it sounds like a very good idea, long overdue :-)
Roro - how did you "listen"? did you disassemble an old lens? a spacer tube like an AF macro ring might be great for this. this way different lenses could be tested.
I would not be surprized if the protocol is really simple. even if not understood the only data we need to know is the max opening and the current opening? perhaps all needed is to fill in the correct data replacing the once found in an test lens. (in case one finds a matching lens it would even be simpler.)
Mike Kovacs , Aug 06, 2004; 07:53 a.m.
Wonderful, long overdue idea! I just hope this doesn't end with Nikon USA smiting you for your efforts.
Ro Ro , Aug 06, 2004; 09:49 a.m.
to Walter: I disassembled a mechanically defective 35-70 and soldered wires direct to the 180R protection resistors. Extension tubes could maybe also do the job but are more expesnsive than a N4004/N50/N55 with broken shutter oder defective back. I try to get an working AF Nikon with defective shutter and solder wires direct to the inner lens connections.
Some on the lens data is decribed in the N90s memory map. (LENS BANK)
http://members.aol.com/khancock/pilot/nbuddy/protocol.html
I think the bytes are the same.
To Mike: I should contiue work on old Sigma lenses, the Nikon's databytes may be covered by US copyright. The protocol is standard I think.
Neil Parker , Aug 06, 2004; 02:30 p.m.
Its greek to me, but if it leads to a way to hack a D70 to meter w/ AI lenses my check will
be in the mail. Unfortunately the lens I truly would like to use (35 1.4) can't be chipped.
