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The perennial USB control issue.

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Offline ocschwar

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The perennial USB control issue.
« on: 20 / March / 2010, 19:12:57 »
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Hi, all. I have a Powershot A530, and just installed CHDK on it, using my Linux laptop. All is working well, including the remote option, which is to say it does take a picture when I put the USB cable in. So now comes the time to ask for something a little fancier, and i looked through the forum to see where things are on that front.

I understand getting any further than that will take time since the USB interface into these cameras is ill documented. However, at least in Linux there is the usb_modeswitch command, which will send the camera any kind of message. So I thought I'd ask for a few details here.

1. how does CHDK deal with the USB connection?
   a. Does it only detect the power line ?
   b. If so, what current draw should this require? 
   c. If it probes for data (my laptop indicates otherwise, but it could be wrong),
      has anyone tried things like just sending the camera some reset messages?

2. has anyone tried using Arduino-type assemblies to connect to CHDK? If CHDK only plays with the
USB power line, that is what it will require, and I may have the time to try it.
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Offline ocschwar

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Re: The perennial USB control issue.
« Reply #1 on: 20 / March / 2010, 19:48:49 »
Okay, to answer my own question, this does involve the power line, not the data line, so nothing is easy, but the power draw is light enough to make it Arduino-able.

However, is there any new functionality lately for getting anything from the data line? If there is, then I can write something in Lua to take care of this.
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Offline Microfunguy

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Re: The perennial USB control issue.
« Reply #2 on: 20 / March / 2010, 19:49:34 »
Quote from: ocschwar on 20 / March / 2010, 19:12:57
   a. Does it only detect the power line ?
Hello and welcome !
That is all the official CHDK version does.

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   b. If so, what current draw should this require? 
Negligible.
With the camera turned off, measure the resistance in kohms across the outer pins of the USB socket.
Divide '5' by that value to get the current in mA.

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2. has anyone tried using Arduino-type assemblies to connect to CHDK?

Someone has sent me a microcontroller that allows two SDM cameras to communicate with each other and exchange settings.
However, that was six months ago and there is no indication that work will continue.

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  c. If it probes for data (my laptop indicates otherwise, but it could be wrong),
      has anyone tried things like just sending the camera some reset messages?

I think you will find this interesting, worth reading all of it :-

http://chdk.setepontos.com/index.php/topic,4338.0.html
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Offline ocschwar

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Re: The perennial USB control issue.
« Reply #3 on: 20 / March / 2010, 22:33:51 »
Oh, NICE! Looking into it now. THank you!
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Offline ocschwar

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Re: The perennial USB control issue.
« Reply #4 on: 20 / March / 2010, 22:38:06 »
Oh, I see. It needs 1.01a, when I have 1.00a. Still, I will certainly keep an eye on this development!
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Offline reyalp

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Re: The perennial USB control issue.
« Reply #5 on: 20 / March / 2010, 23:06:38 »
Quote from: ocschwar on 20 / March / 2010, 22:38:06
Oh, I see. It needs 1.01a, when I have 1.00a. Still, I will certainly keep an eye on this development!
I think you are confused. Those are canon firmware versions, and the only known canon firmware of the A530 is 100a. These firmware versions numbers are revisions of the firmware for a specific camera model, so 100a on the a530 doesn't have any special relationship to 100a on some other camera. Support of a particular CHDK feature on other cameras is irrelevant to support on your camera, regardless of the canon firmware version numbers involved.

The PTP stuff is only implemented for some cameras. If it is implemented for a camera, then all firmware versions of that camera supported by CHDK would probably be supported.
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Offline ocschwar

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Re: The perennial USB control issue.
« Reply #6 on: 20 / March / 2010, 23:07:40 »
And last comment for the day: I have the trunk checked out, gcc-arm installing, and will try to build this patched CHDK this week.
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Offline ocschwar

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Re: The perennial USB control issue.
« Reply #7 on: 20 / March / 2010, 23:08:59 »
Er, yes, that's what I mean. The patch is being tested against many firmware versions, but 100a is not among them yet, unless I succeed in making it so. Which I am working on.
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