Canon 70D Shutter Speed Timing / Firmware - DSLR Hack development - CHDK Forum
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Canon 70D Shutter Speed Timing / Firmware

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Offline jonas.svidras

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Canon 70D Shutter Speed Timing / Firmware
« on: 24 / June / 2017, 12:24:35 »
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Hello Guys!

So, the story is that recently I disassembled my Canon EOS 70D, replaced my broken shutter blades and did CMOS sensor position measuring and aligning after assembly using 0.001 mm scale.

Everything works fine, kinda... But my photos a little bit underexposed, they not that dark, but there is a slight push to the left in histogram.



As I know that means that my camera needs Shutter Timing Alignment.

There is few possible ways to do this that I have in mind:

1. Bring camera to Canon Authorized Service;

2. Buy SPT Software for $275.



What I understand it works directly using USB, it puts camera in to service mode and you can rewrite Shutter Timing Value.

3. Maybe there is posibility to decrypt original Canon firmware file(.FIR), change these values and then compile it back and flash to camera. Or maybe there is a way to directly modify these values like that SPT software does? As I understand it's not official Canon Service software. Or maybe I need to extract firmware from my camera to be able to modify it... I just don't know... Just going thru this whole forum and wiki to find any kind of information about this.

I would love to hear your thoughts on this, maybe you know what's possible and what's not, every, even small bit of information will be really helpful to me.  ;)

Thank you! Hope this is the right section for this.

Jonas
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Offline dmitrys

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Re: Canon 70D Shutter Speed Timing / Firmware
« Reply #1 on: 24 / June / 2017, 13:20:17 »
Welcome to the CHDK forum!

Your question is best asked in the Magic Lantern forum, since they are the people who deal with Canon's DSLRs (there's even an unofficial ML build for 70D).
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Offline jonas.svidras

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Re: Canon 70D Shutter Speed Timing / Firmware
« Reply #2 on: 25 / June / 2017, 09:51:58 »
Thank you for answer, I posted my question in ML Forum as well.

Just some information:

As service manuals says:
Quote
This board also has the following: Main CPU which controls various sensors and
mechanical parts for camera operations, viewfinder display drive control circuit, and
EEPROM memory to store saved data such as adjustment data (AE, AF, etc.)

I think these values, including shutter timing is stored in EEPROM 8-pin chip that is located on main board.

   

There is no information online how to put camera in to Service Mode, or even if I would be able to get camera to Service Mode, I wouldn't be able to find drivers for this mode, because I think drivers is a must for accessing EEPROM.

I got an idea to dissasemble my main board, remove EEPROM and try to read it with programmer.

For practice I removed EEPROM from my Canon printer to read EEPROM, but what I get it's just "random" symbols. Maybe I need to decrypt it or I should go straight for my camera, and hope that values on EEPROM will be different and clear to understand... I don't know... My camera is working, I can use it with exposure compensation...



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Offline waterwingz

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Re: Canon 70D Shutter Speed Timing / Firmware
« Reply #3 on: 25 / June / 2017, 11:46:16 »
Quote from: jonas.svidras on 25 / June / 2017, 09:51:58
For practice I removed EEPROM from my Canon printer to read EEPROM, but what I get it's just "random" symbols. Maybe I need to decrypt it or I should go straight for my camera, and hope that values on EEPROM will be different and clear to understand...
If you were expecting the EEPROM contents to be "human readable" (i.e. nice English language text strings) and easy to understand, then I'm afraid you are most likely going to be disappointed. Values stored there are most likely just binary numbers with no other identification.  Your camera's firmware "knows" where each value is stored (addresses are created as part of the process of creating the camera's firmware).

For you to understand what any particular EEPROM value is used for, you typically have to find where it is referenced in a disassembly of the firmware and then understand what that part of the firmware is doing. Or you need to "guess" what lens calibration data would look like and then find that pattern in the EEPROM - an almost impossible task unless you get really lucky.

Living with a permanent eV offset value seems like the easiest route.
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