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Powershot A420 port

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Offline srsa_4c

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Powershot A420 port
« on: 25 / June / 2011, 12:49:03 »
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Hi!

I started to port this old camera. Sources (diff against trunk r1211) and a "beta1" binary release are attached.
A few notes:

Quote
- The A420 does not have an iris diaphragm, it has a smaller snap-in aperture (not an ND filter)
  Seen this in a dismantled A430 optics, suspect the same in at least the A410 - A430 models.
  The CHDK controls this the same as an ND-filter.


LED ADDRESSES

AF_LED      0xC0220080
BLUE_LED   0xC0220084
RED_LED      0xC0220088
GREEN_LED   0xC022008C
ORANGE_LED   0xC0220090

Changelog

Beta 1, 2011-06-25

- based on A430, thanks to the authors of that port
- haven't checked the automatically found stubs, only the overrides (the two models are closely related, I assumed)
- the loader part almost identical (changed one led address in an inactive function)
- USB completely untested, don't know if it works or not, A430 stuff without change
- no video control (not yet ported)
- optics stuff unchanged, don't know if it's correct or not

- sensor data the same as in A430 (probably the same sensor in the two models)
- RAW/DNG works, RAW not recognized by anything (probably because A430 is still beta, nobody cared)
- RAW/DNG file numbers work as expected (using hack from A530)
- extra long exposures work (tested with 80sec), shutter speed override works
- flash adjustment seems to work
- zebra seems to work (not fully tested)
- grids work
- histogram works (not fully tested)
- manual focusing works, but barely usable (small viewfinder resolution)

As the mechanical shutter and the "ND-filter" (see above) is broken in my camera, can't test their functionality.
Crashes, when trying to view page >= 10 of params debug, reason unknown, bug inherited from the A430 port.
Movie mode used to exhibit some funny things, better avoid using it for now.
There might be other bugs, use it with caution.

Dump of the 1.00b firmware is available
here.

Binary:
Zshare link gone, use the recent one at the end of this thread.


Sorry for my bad english...
« Last Edit: 09 / September / 2011, 16:14:08 by srsa_4c »
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Offline reyalp

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Re: Powershot A420 port
« Reply #1 on: 25 / June / 2011, 16:09:10 »
Very nice.

Quote
- RAW/DNG works, RAW not recognized by anything (probably because A430 is still beta, nobody cared)
Nothing to do with "beta" specifically. CHDK raw is just a copy of the sensor, so programs that want to read it need to update any time the sensor is in a different layout. See http://chdk.wikia.com/wiki/Raw

Quote
Crashes, when trying to view page >= 10 of params debug, reason unknown, bug inherited from the A430 port.
This probably means get_flash_params_count is wrong (on both)
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Offline srsa_4c

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Re: Powershot A420 port
« Reply #2 on: 25 / June / 2011, 17:54:15 »
Quote from: reyalp on 25 / June / 2011, 16:09:10
Very nice.
Thanks :)

I've found the correct value for get_flash_params_count (108) by trial-and-error, will correct it in the next release.

I also plan to make patches for the A430, but not until I could verify those suspicious looking parts of the code.
Which is the preferred format for patches? I don't currently use svn functionality for this, just plain diff. Is that ok?

About RAW:
I've been using CHDK on my SX100IS for almost 3 years now, so I know about the headerless RAW.
I tried DNG2PS2, it is able to handle the sensorsize used in the A430, and of course it works for the A420 RAWs too. It's dcraw and the programs based on it that do not work (yet).
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Offline reyalp

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Re: Powershot A420 port
« Reply #3 on: 25 / June / 2011, 18:28:00 »
I prefer a patch made svn from a working copy of the current trunk, with all the new files added with svn add. This is very easy if you are using tortoise on windows.

If that's not possible, a regular patch or zip of the source tree is OK. If you do make a zip, please make it just include the source, not binaries, .svn directories etc.
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Offline fe50

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Re: Powershot A420 port
« Reply #4 on: 26 / June / 2011, 06:12:38 »
Quote from: srsa_4c on 25 / June / 2011, 12:49:03
- The A420 does not have an iris diaphragm, it has a smaller snap-in aperture (not an ND filter)
  Seen this in a dismantled A430 optics
Interesting... do you have any pictures ? how does it look like ?

If this camera use such a "real" aperture, DOF should (in contrast to a ND filter) be changed !?
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Offline fe50

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Re: Powershot A420 port
« Reply #5 on: 26 / June / 2011, 06:23:26 »
Quote from: fe50 on 26 / June / 2011, 06:22:58
Added the A420 1.00B dump (full 4MB dump, by srsa_4c) from this post to the box.net/chdk repository.
Thx srsa_4c !
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Offline srsa_4c

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Re: Powershot A420 port
« Reply #6 on: 26 / June / 2011, 08:13:20 »
Pictures of the shutter assembly of an A430 (slightly offtopic).


wide aperture


narrow aperture


narrow aperture, other side

Unfortunately, I can't test DOF right now, because my only A4xx camera, which is not broken yet is an A410. The original firmware provides no manual control over the aperture.

These pictures also show the common cause of malfunction in these cameras, the broken flat cable.
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Offline fe50

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Re: Powershot A420 port
« Reply #7 on: 27 / June / 2011, 01:23:36 »
Thanks for the pics !

So we have 3 types of "aperture" on our Powershots:
a) adjustable iris diaphragm aperture (e.g. SXxx Series, SX10)
b) adjustable fixed size aperture (A420, A4xx series ?)
c) ND filter for simulated aperture (IXUS / SD series, e.g. SD400, SD860)
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Offline zfeet

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Re: Powershot A420 port
« Reply #8 on: 18 / August / 2011, 02:12:09 »
Quote from: srsa_4c
I've found the correct value for get_flash_params_count (108) by trial-and-error, will correct it in the next release.

I never managed to find the correct value when porting A430 so thanks a lot!
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Offline srsa_4c

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Re: Powershot A420 port
« Reply #9 on: 21 / August / 2011, 21:05:51 »
Here's another release, the so-called beta2.

Changes:
Quote
- modemap is now correct
- movie mode is now supported (quality override, zoom, af-scan, exposure override works, filesize can grow over 1GB)
- aperture table corrected
- movie time limit lifted to 1 hour / recording in 320x240 and 640x480 modes
- USB remote should work

Bugs (it should be called an "issue" instead)
- AF-scan causes crash during 640x480 movie recording, works fine otherwise

Camera specific CHDK behaviour:

- enabling both "video quality control" and "enable optical zoom" in the "video parameters" submenu is not recommended
  pressing the up/down buttons would zoom AND change compression quality at the same time

About my earlier note:
Quote
Movie mode used to exhibit some funny things, better avoid using it for now.
It turned out to be a hw problem in my worn-out camera.

The port is now ready for an "alpha" status in trunk, if somebody wants to add it.

I have also included some code to lift the movie time limit even further (it's optional, defined locally in movie_rec.c)

@zfeet:

It's the same for the A430 too. As I stated here earlier, I plan to do some corrections for that model. Fortunately, I was able to reach shentey's git-repo which will hopefully enable me to analyze the progress of the code (I suspect, capt_seq.c contains some copy-paste errors which - surprisingly - do not seem to affect anything).

Edit:

For those, who are interested: the attachment named "a420_chdk_r1302.diff" is the source patch which adds this port to the chdk trunk rev. 1302.
The bigger attachment is the binary release, which is for those who don't want to compile it themselves.

If somebody can actually try it, I'd appreciate some feedback  ;)

Edit n+1:

In case the attachment links don't work, here's an alternative link for the binary, zshare (should be valid for a few weeks).
« Last Edit: 24 / October / 2011, 17:17:23 by srsa_4c »
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