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Matrix metering chips


ro_ro

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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?

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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.

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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.)

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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.

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Ro Ro,

 

How are the efforts going? To me it looks like that 1) is an interupt signalling end of a transfer. 2) is the clock signal and 3) is the actual data.

 

If you need some help converting this serial data to parrallel format, send me some data you sampled and I will write a translator (I have done things like that before)

 

Paul

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Many thanks for your help. I got further now.

 

I made a first test with a PIC (containing my special emulation software ;) connected to a N4004. The timing diagrams shown in the patent were very helpful, but the datebyte described are different from what I discovered. There are 26byte transferred instead to the 16byte in the patent. It works, the camera tries to AF (I took databytes from an AF lens) with only my PIC attatched.

 

The bad news: Newer Nikons use a high speed clock, so the PIC cant't follow and no real data is transmitted :(

 

The serial port in the NEC chip could handle clock rates of serveral 100kHz. My software serial port could only do 20kHz.

 

ToDo: Get a faster micro or one with a hardware serial port. Case should be SO8 or smaller to be put in lenses with almost no space.

 

I won't post any software or schematics in public to get not in trouble with Nikon. I only tell what can be done to get a working chip. More in next week.

I still don't know what most databyte exacly do, but I gussed aperture and focal length.

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"don't know what most databyte exacly do, but I gussed aperture and focal length."

 

well somewhere must also the "D" info come in. but you will see this by comparison of "D" with "non D" lenses once you got the hardware running.

 

 

by the way where are you located on the globe. perhaps someone sharing the interest is close to you.

cheers

walter

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'D' chips are different to the old AF ones. Not only the distance information is transmitted, but also values for AF and other compensation values change.

 

This works even on old cameras that use protocol 0x22. Newer cameras that include the 'D' feature use 0x25, 0x27 and 0x28 protocols for the 'D' chip lenses. These newer protocols provide addition information.

 

My opinion is that even on older cameras a 'D' lens can provide better AF and metering.

 

But for an upgrade of old lenses the 'D' isn't important. So only a basic 0x22 protocol used with the first AI-P lenes is needed.

 

 

I got further using a fast AVR instead of a PIC. Clocked at 8MHz the AVR can handle clock speeds of 100kHz, but current consumption is too high (8mA). My old N4004 has problems with mirror and shutter if a chip takes more than 5mA.

The old NEC chips take 1mA and the new AF-D ones take 5mA. Another problem is the missing capacitor on the power pins of the micro. AVRs don't work fine without this capacitor. The chips Nikon uses do.

The old NEC 4-bit line is now obsolete and could not be used for a self-made chip. The new 'D' chip have 48pins are clock at 8MHz and have a Nikon logo, I don't know what's inside.

 

I still haven't found a suiting micro and my time is limeted. For now I stop research on make compatible chips.

If anyone wants to continue my work, please write me an email.

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  • 2 years later...
  • 2 years later...
  • 3 weeks later...
  • 2 weeks later...

Hello,<br />

<br />

1° They managed to program a chip with any lens data.<br />

2° It works on an old F8008 but too they're too shy to test on F5,D200 and so on.<br />

3° They didn't manage to make new contact blocks ( hardware part of the project ).<br />

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