I'm trying to reverse engineer the rest of the Micro 4/3 lens protocol.
I found an interesting macro adapter that sits between mft camera and mft lens and has electrical contacts.
Thus I'm trying to modify this adapter and analyze not only one lens but a large number of combinations of lenses and cameras.
I'm currently working on this.
Setup
Pinout:
VDD=microcontroller power (goes low on lens-release button)
VCC=battery power (possibly for AF-motor,...)
preliminary MFT pinout:
| signal | logic analyser cable | logic analyser channel | position |
| ACK? | BROWN | CH4 | Right when Facing the Sensor |
| ACK? | RED | CH2 | |
| Clock | ORANGE | CH3 | |
| Data | YELLOW | CH1 | |
| Lens2Body? | GREEN | CH0 | |
| Body2Lens | BLUE | CH5 | |
| GREY | CH7 | ||
| ??? | PINK | CH6 | |
| WHITE | GND | ||
| BLACK | GND | ||
| FEHLER(N/C) | --- | --- | Left when facing the sensor |
Quote about the 2 additional contacts (from here):
In addition, the lens mount of the Micro Four Thirds System is equipped with two additional signal contacts for smoother Live View shooting with shorter time lags, faster higher communication speeds between the lens and body, and, of course, reduced lens and camera size.
These two contacts will also be used in high-speed data processing required for the movie handling capability expected in the future.
(Image again taken from Lasse Bayer)
SPI seems to be used at 500KHz with 8 bits LSB. Lens2Body and Body2Lens are pulled high by lens or body respectively to indicate that they are ready to receive/send the next byte and pulled low again to acknowledge the receipt.
The camera seems to pull the lines low (including clock) to pause communication.
- when the shutter is pressed
- when exposure has finished
(confirmed for MFT)
General protocol
Everything seems to start with 4 byte commands sent by the camera to the lens,followed by the lens answering.
Initial communication
FT: B0 F0 00 00 (first command on switch-on)
MFT: B0 F0 00 00
FT:
Followed by 2 values: A0 00
MFT:
Followed by 2 values: 00 00
Command: request lens data (MFT)
MFT: 80 ED 01 00
TODO: followed by some yet unknown data
Command: request lens data (FT)
FT: C0 F0 20 00There is quite a lengthy answer in 26 blocks:
Block 0
lens Idlens designation(ASCII)
lens serial number
lens firmware version
number and length of the following blocks
TODO : details
Block 1
May be a list of all focal lengthes in mm - 1Block 2
unknownBlock 3
unknownBlock 4
unknownBlock 5
unknownBlock 6
unknownBlock 7
unknownBlock 8
unknownBlock 9
unknownBlock 10
unknownBlock 11
unknownBlock 12
unknownBlock 13
unknownBlock 14
unknownBlock 15
unknownBlock 16
unknownBlock 17
unknownBlock 18
unknownBlock19
unknownBlock20
unknownBlock21
unknownBlock22
unknownBlock23
unknownBlock24
unknownBlock24
unknownBlock25
unknownBlock26
unknownRegular polling (MFT)
TODO: MFT seems to use multiple, regular polls.81 E3 04 03
followed by yet unknwn data that does change while not touching the camera.
Regular polling (FT)
C0 F1 0 0Apparently the camera polls the lens every 104ms sending these 4 bytes.
The lens answers with 14 bytes including information on the current focus, focus mode, zoom distance, and a checksum.
(I'll insert details here)
Here is what Lasse found out:
Byte Number:
1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10, 11, 12, 13, 14, 15, 16, 17, 18
----------------------------------------------------------------------------------------
Infinity focus:
192, 241, 0, 0, 177, 11, 0, 160, 0, 31, 255, 255, 2, 5, 0, 0, 0, 196
Focusing closer:
192, 241, 0, 0, 177, 11, 0, 128, 0, 31, 43, 1, 2, 5, 11, 2, 0, 223
192, 241, 0, 0, 177, 11, 0, 128, 0, 31, 155, 0, 2, 5, 85, 3, 0, 153
192, 241, 0, 0, 177, 11, 0, 128, 0, 31, 87, 0, 2, 5, 121, 5, 0, 123
Close focus:
192, 241, 0, 0, 177, 11, 0, 144, 0, 31, 78, 0, 2, 5, 254, 5, 0, 7
----------------------------------------------------------------------------------------
Byte 8: 0 - 0000 0000 - Single Autofocus active
160 - 1010 0000 - Manual Focus @ infinity
144 - 1001 0000 - Manual Focus @ close-up
128 - 1000 0000 - Manual Focus in between
Byte 10: Changes linearly while zooming from 31 @ 45mm to 0 @ 14mm
Bytes 11 + 12: FF FF - 65535 - infinity focus
4E 00 - 78 - close focus
Focus distance ?
Bytes 13 + 14: Seem to depend on the zoom position at switch-on.
Do not change while zooming or focusing manually.
Bytes 15 + 16: 00 00 - 0 - infinity focus
FE 05 - 1534 - close focus
Focus mechanism position ?
Byte 18: Checksum of Bytes 8 to 17, maybe 7 to 17
The first 4 Bytes are sent from Body to Lens, the remaining 14 from Lens to Body.
Command: Start/Stop exporure (FT)
A0 B0 FE 0 ? stop of exposure ? A0 B1 0 0 ? start of exposure ?TODO: different on MFT
Command: Change Aperture (FT)
Like the polling is a 4 byte sequence, this seems to be 4 byte too.close aperture: 176 210 xxx xxx open aperture: 176 215 0 0TODO: verify list of epertures
Aperture values as determined by Lasse:
aperture command
value data
estimated
1.0 0 0
1.1 85 0
1.2 170 0
1.4 0 1
1.6 85 1
1.8 170 1
2 0 2
2.2 85 2
2.5 170 2
2.8 0 3
3.2 85 3
3.5 170 3
determined my own notes:
4 0 4 (base value for comparison) 4.5 85 4 (+85 ) 5.0 170 4 (+170) 5.6 0 5 (+256) 6.3 85 5 7.1 170 5 8 0 6 9 85 6 10 170 6 11 0 7 13 85 7 14 170 7 16 0 8 18 85 8 20 170 8 22 0 9
determined
3.5 157 131 my own notes:
3.6 171 131
3.7 198 131
3.8 211 131
3.9 236 131
4.0 248 131 (base value for comparison)
4.1 17 132
4.2 28 132
4.3 51 132
4.4 62 132
4.5 84 132 (+77 instead of +85 =-10%)
4.6 106 132
4.7 116 132
4.8 137 132
4.9 156 132
5.0 166 132 (+162 instead of +170 =-5%)
5.1 176 132
5.2 195 132
5.3 213 132
5.4 222 132
5.5 231 132
5.6 249 132 (+257 instead of +256 =+0,4%)
Quote from a camera manufacuter I recently got:
"The electronic feedback from the lens tells the camera where it is in regards to f-stop, and the camera then interprets that information."
Command: shutdown (MFT)
Sadly the shutdown sequence seems to use different commands.No clear command sequence to see yet.
-->
| 14-42PZ | 14-42PZ | 14-42PZ | 14mm | 14mm | 14mm | 14mm | |
| 23,89ms | 12,32ms | 32,09ms | 14,06ms | 29,83ms | 21,92ms | 23,86ms | |
| SDO: A1 D7 00 00 11 05 7D 07 | SDO: F1 CF 00 00 11 05 7D 07 | SDO: B1 D7 00 00 11 05 7D 07 | SDO: 31 CF 00 00 08 04 3F 02 | SDO: 31 C7 00 00 08 02 BF 00 | SDO: 21 9E 00 00 00 00 3F 00 | SDO: F0 9E 00 00 80 00 BE 06 | |
| SDI: A1 D7 00 00 11 05 7D 07 | SDI: F1 CF 00 00 11 05 7D 07 | SDI: B1 D7 00 00 11 05 7D 07 | SDI: 31 CF 00 00 08 04 3F 02 | SDI: 31 C7 00 00 08 02 BF 00 | SDI: 21 9E 00 00 00 00 3F 00 | SDI: F0 9E 00 00 80 00 BE 06 | |
| lens folding up... | lens folding up... | lens folding up... | |||||
| 716,8ms | 705,43ms | 725,16ms | 336,96ms | 352,76ms | 344,85ms | 346,89ms | |
| SDO: 42 FF 07 00 C6 16 02 00 | SDO: 62 FD 03 00 C6 16 02 00 | SDO: 42 FF 03 00 C6 16 02 00 | SDO: E2 FF 07 00 60 08 00 00 | SDO: 62 FF 03 00 C2 12 00 00 | SDO: 42 FE 07 00 C0 10 00 00 | SDO: E0 FF 07 00 C0 10 00 00 | |
| SDI: 42 FF 07 00 C6 16 02 00 | SDI: 62 FD 03 00 C6 16 02 00 | SDI: 42 FF 03 00 C6 16 02 00 | SDI: E2 FF 07 00 60 08 00 00 | SDI: 62 FF 03 00 C2 12 00 00 | SDI: 42 FE 07 00 C0 10 00 00 | SDI: E0 FF 07 00 C0 10 00 00 | |
| 790,6ms | 761,32ms | 794,78ms | 393,21ms | 414,12ms | 370,9ms | 384,84ms | |
| SDO: 7C 31 10 | SDO: 7C 31 10 | SDO: 7C 31 10 | SDO: E0 00 08 | SDO: C0 00 0C | SDO: E0 00 18 | SDO: E0 00 18 | |
| SDI: 7C 31 10 | SDI: 7C 31 10 | SDI: 7C 31 10 | SDI: E0 00 08 | SDI: C0 00 0C | SDI: E0 00 18 | SDI: E0 00 18 | |
| VDD going low | VDD going low | VDD going low | VDD going low | VDD going low | VDD going low | VDD going low |
I also looked at this on the Blackmagic Pocket Cinema Camera...
not only does the #BMPCC not send the proper lens shutdown sequence, it also has some really bad noise on the VDD line while being switched off.
Command: prepare for shutdown (FT)
176 160 0 0 prepare for shutdown
TODO: verify
Command: focus
176 161 xxx xxx change focus to/by value 176 173 0 0 start single autofocus
TODO: verify
Other commands
192 241 0 0 poll 192 246 0 0 ?(sent after initial command and before requesting the full lens data)) 192 250 xxx xxx ? 192 251 0 0 ?TODO: analyse these
- Previous work
- 30C3 project page
- Arduino SPI library (Master only)
- Existing thread about the pinout (photo)
- Photos (coming soon)
- Similar adapter for Canon EF
- Attempt to decode Canon EF (German)
- Magic Lantern lens.h (for comparison to identify similarly coded values)
- Microcontroller rig to mount Canon lenses to Sony cameras
