micro 4/3 lens electronic pinout for the focus control

P

Picturequest

Well-known member
Hello!

Before I reinvent the wheel, does anyone know the specs for micro 4/3 lens electronic pinout for the motor control? Since these lenses are shared amongst brands for autofocus, aperture, etc, I'd like to know what each pin does?

My idea was to make a paper thin ring with gold contacts on each side, like the ribbon cables used to connect laptop LCD displays. The signal would just pass through, but have a connector that can be tapped outside the lens.

With something like an Arduino microcontroller, you could monitor the signals, for focus etc. Then you'd be able to add an external potentiometer and let the Arduino send the focus signals.

So now you could have a relatively inexpensive electronic, or even wireless follow focus on any of you auto focus lenses.

I'm thinking, you could also do the same approach on a Nikon or Canon. Once the Arduino knows how to control the lens, you could add that to a m 4/3 adapter and use the internal motors of a canon/Nikon lens with the EFF (Electronic Follow Focus).

I can't imagine the signals from the camera to the lens to focus in or out would be to complicated.

So if anyone knows of the lens specs, please let me know.

Max
 
For Canon Lenses:

Pinout and pin functions:
Left to right, looking at the front of the body:
1. VBAT
2. P-GND 3. P-GND (pins 2 & 3 are common on the lens)
4. VDD
5. DCL
6. DLC
7. LCLK
8. D_GND
Pin Functions
VBAT - Motor power
P_GND - Motor power ground
VDD - Logic circuitry power
D_GND - Logic circuitry ground
DCL - Data from body to lens
DLC - Data from lens to body
LCLK - Clock
Data protocol: Motorola SPI; 8 bit serial; Such as the protocol used with the 68HC05 chip.
--
 
The basic Nikon interface is 5 pins, Vcc (regulated power), RW1 (tach), SCK (serial clock), SIO (serial data), gap, gap, LGND (ground). That's enough to power a lens's little CPU (power and ground), communicate with it (clock and data), and monitor the motion due to the AF motor (tach).
For AF-S and AF-I lenses, they fill the gap with RW2 (clock in quadrature with RW1) and LBAT (unregulated power) for 7 pins.
Some lenses add an extra high current ground, for 8 pins. High end Nikon cameras have 8 pins, cameras with lower power electronics have 7.
And higher end AF-S lenses add two more pins for communication between the chips in the lens and AF teleconverter. That's why they're typically only seen on larger AF-S lenses that make sense to use with teleconverters. Nikon cameras have 7 or 8 pins, teleconverters have 10.


Pin 8 is an extra ground, which helps with the lenses with big motors. Pins 9 and 10 are for teleconverters.
 
It doesn't appear to be useful information without knowing the message format. From the pin descriptions, the interface is message based, and will not accept a signal from a potentiometer for focus or zoom, if that is your intention, as it was with the OP.
 
I'd check for patents. Those would describe a lot of details, even messages. The Canon EF patents lay out the messages and a ton of information.
 
only known LSB2A
LSCK - clock
LSDIO - ??? may 1 wire bus (or JTAG)
LSL2B - LENS to BODY
LSB2L - BODY to LENS
LSRST - RESET (may be fot JTAG)
LSDET - may be Lens Detect (pin on lens short to GND)
But pins numbers unknown
 
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