Ramote Control and USB

alvm

123

« on: 27 / February / 2013, 13:47:30 »

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Hi,

I see in kbd.c that for remote control chdk clear USB bit (for a800 for example) so a cam always think that USB cable is not connected. But how does USB part of canon f/w work in this case?

Thanks,
Alex.

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waterwingz

12139

Re: Ramote Control and USB

« Reply #1 on: 27 / February / 2013, 14:38:03 »

Quote from: alvm on 27 / February / 2013, 13:47:30

I see in kbd.c that for remote control chdk clear USB bit (for a800 for example) so a cam always think that USB cable is not connected. But how does USB part of canon f/w work in this case?

It only does that in <ALT> mode. When that happens, Canon USB firmware is essentially disabled.

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Ported : A1200 SD940 G10 Powershot N G16

alvm

123

Re: Ramote Control and USB

« Reply #2 on: 27 / February / 2013, 14:47:00 »

Quote from: waterwingz on 27 / February / 2013, 14:38:03

It only does that in <ALT> mode. When that happens, Canon USB firmware is essentially disabled.

Yes, but how does work Remote Control (as I understand it uses USB) and ptp client?

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waterwingz

12139

Re: Ramote Control and USB

« Reply #3 on: 27 / February / 2013, 15:02:59 »

Quote from: alvm on 27 / February / 2013, 14:47:00

Yes, but how does work Remote Control (as I understand it uses USB) and ptp client?

I guess the question is what do you mean by "remote control"?

The USB bit you are seeing in kbd.c is used to determine if there is +5V present on the USB power pin. CHDK uses the presence or absence of that voltage as a "remote" signal to indicate something should happen (like take a photograph).

PTP functionality is accomplished by communications over the two data lines on the USB conneector.

The two "remote controls" are completely different things.

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Ported : A1200 SD940 G10 Powershot N G16

alvm

123

Re: Ramote Control and USB

« Reply #4 on: 27 / February / 2013, 15:15:17 »

I mean remote control using USB transport like ptp client but as I inderstood from your words chdk's remote control uses USB power line for control. So when USB bit is cleared by chdk USB doesn't work and ptp can't be used, right?

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