Author Topic: Canon 850D / T8i  (Read 2504 times)

names_are_hard

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Canon 850D / T8i
« on: November 26, 2021, 04:28:37 PM »
I was taken by a fey mood, and have produced this:



This was my first time porting to Digic 8, and it's a bit different from the existing Digic 8 cams I've looked at.  There's a very important change to early boot process that was hard to determine, initialising the second core has changed.  Everything else seems normal enough so far, Kitor helped with the Ximr stuff, it seems to be closest to RP.

Dumped the roms with Basic.  Works well enough in Qemu to test the very early code, although Qemu will need updating due to the boot process change, MMIO addresses are used differently and Qemu assumes all D8 will be the same.  I haven't tried UART yet but the connector is under the thumb grip as is common on modern cams.

I don't recommend anyone try to run this yet, but the source may be useful for people looking at other D8 cams: https://github.com/reticulatedpines/magiclantern_simplified/commits/850d_initial_stubs

Buttons aren't mapped yet, graphics don't display how I'd expect, etc, lots of other bugs I'm sure.  I'll try to improve it to the same state as 200D.

names_are_hard

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Re: Canon 850D / T8i
« Reply #1 on: January 02, 2022, 01:59:55 AM »
Got some features working (also on 200d).

Shutter count zero appears accurate for 850d:


Benchmarks and screenshots work (not all benchmarks tested):

Wlad81

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Re: Canon 850D / T8i
« Reply #2 on: January 02, 2022, 11:14:50 PM »
Was the card reader overclocked?
Canon EOS 5D Mk III + Canon 24-105 F/4 L IS USM + SanDisk Exreme Pro 64 GB (SD, ML Nightly.2021Feb07.5D3113) + SanDisk Extreme Pro 128 GB (CF).

kitor

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Re: Canon 850D / T8i
« Reply #3 on: January 03, 2022, 12:08:34 AM »
No, it does UHS-I natively.
Too many Canon cameras.

Walter Schulz

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Re: Canon 850D / T8i
« Reply #4 on: January 03, 2022, 02:28:09 AM »
Was card reader overclocked?

Measurements by https://cameramemoryspeed.com show that SD-card equipped cameras with Digic 6 and up support 104 MByte/s UHS-I transfer mode and numbers between 50 and 100 MByte/s should be expected without overclocking.

Wlad81

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Re: Canon 850D / T8i
« Reply #5 on: January 05, 2022, 12:03:45 AM »
Great. I wonder, what speed would it give with overclocking.
Canon EOS 5D Mk III + Canon 24-105 F/4 L IS USM + SanDisk Exreme Pro 64 GB (SD, ML Nightly.2021Feb07.5D3113) + SanDisk Extreme Pro 128 GB (CF).

kitor

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Re: Canon 850D / T8i
« Reply #6 on: January 05, 2022, 09:59:54 AM »
You know that OC right now is specific to Digic 5 models, right?

And it is "overclocking" controller to force it to use higher data modes (UHS-I modes on "regular" controller).

In case of Digic 8 it already has UHS-I and UHS-II support. If model does not support UHS-II it is a hardware limit - UHS-II mode requires additional connections between card and a host (second row of contacts).
Some UHS-II Digic 8 benchmarks area in EOS R thread
Too many Canon cameras.