analog video detect as a remote input

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Offline reyalp

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analog video detect as a remote input
« on: 07 / June / 2018, 02:36:51 »
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Following on from this post https://chdk.setepontos.com/index.php?topic=12692.msg137306#msg137306 by @hugoboss00
I remembered the cameras detect when you plug in the analog AV adapter cable into the USB port as documented on http://www.achillies.com/CHDK_Files/USB_Splitter.htm (from https://chdk.setepontos.com/index.php?topic=5691.msg62525#msg62525)

On g7x, physw_status[1] bit 0x8000 goes 0 when the cable is plugged in. Forcing it to 1 in kbd_update_physw_bits causes the video adapter to be ignored.

Advantages to using this over regular USB +5v:
1) Doesn't require a +5v source, just need to connect the pins (6 and 11 per achilllies doc linked above)
2) Doesn't need software hacks to work at the same time as PTP
3) For large multicam rigs, don't deal with cutting power after the hubs

Disadvantages:
1) Needs a proprietary or custom connector
2) Bit needs to be found
3) Some code needs to be added to support this as a remote input
4) Need code similar to get_usb_bit to read it.

Since I don't have anything that displays analog out and haven't built the spliter, I used the following in chdkptp to find the bit
Code: [Select]
=r={} phw=0x36c10 for i=1,10 do table.insert(r,string.format('0x%08x 0x%08x 0x%08x',peek(phw),peek(phw+4),peek(phw+8))) sleep(1000) end return r
... swap to AV cable before 10 seconds is up, swap back to usb ...
connect
getm
Don't forget what the H stands for.

Re: analog video detect as a remote input
« Reply #1 on: 13 / June / 2018, 02:42:28 »
I would like to implement this also for G7X, but unfortunately i dont have this 11 pin USB connector.
As soon i can get one i will add it to the multichannel remote patch. see https://chdk.setepontos.com/index.php?topic=13451.0
do you have a source where to get this connector?
G7X - CHDK 100d

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Offline reyalp

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Re: analog video detect as a remote input
« Reply #2 on: 13 / June / 2018, 03:15:55 »
I would like to implement this also for G7X, but unfortunately i dont have this 11 pin USB connector.
As soon i can get one i will add it to the multichannel remote patch. see https://chdk.setepontos.com/index.php?topic=13451.0
do you have a source where to get this connector?
Assuming you just want the video related pins, you can probably hack up a Canon cable or clone, search for AVC-DC400 or AVC-DC400ST.

If you want both video and USB, the only option seems to be the DIY one linked in the first post. edit: Appear to be available from https://vp-systems.eu/order_cr.html

There is another 11 pin mini-USB compatible plug, panasonic part AXJ443000
https://www3.panasonic.biz/ac/e/control/connector/interface-sm/connector-miniio/index.jsp

The external housing looks different, but it's possible the part with the pins is close enough.

Gopro also uses a proprietary mini USB, but it's 10 pins and they appear to be aligned with the standard USB pins. Pity since there are lots of breakout cables available.
« Last Edit: Yesterday at 22:23:24 by reyalp »
Don't forget what the H stands for.

Re: analog video detect as a remote input
« Reply #3 on: 19 / June / 2018, 16:39:13 »
Advantages to using this over regular USB +5v:
1) Doesn't require a +5v source, just need to connect the pins (6 and 11 per achilllies doc linked above)
2) Doesn't need software hacks to work at the same time as PTP
3) For large multicam rigs, don't deal with cutting power after the hubs
I don't know how I missed, until now, this and related "HDMI power and alternative remote inputs" threads - very interesting.

I'm not up to speed on either yet but don't wish to hold back with the following query - does Point 1 above infer pin 6&11 must be closed by a physical relay, similarly to:
The advantage of this is that the reed switch would just need to switch to ground or open circuit (or open circuit and the original terminal), not +5v.
?

I tested Hardware_Hackers suggested USB Adapters (https://chdk.setepontos.com/index.php?topic=13294.msg136643#msg136643) hacked to include a normal switch cable on the output side of the hubs a while ago and, in limited testing of a 16 number camera system, ptp reliability seemed very good while a precision sync build (without detailed results to confirm) "seemed" to provide very good precision.


However, I am, perhaps mistakenly, concerned that the loose coupling of the switch cable supply and return paths could result in creating a very large loop antennae and problems as the system is expanded - the video cable solution would be very much more tightly coupled, presumably, decreasing any possible ill effect from that. On the other hand, if relatively slow mechanical relays are the only way to short pin 6&11 (preferably under microprocessor control) it seems "good" precision sync would not be obtainable across a large camera count.

I know (admittedly little circuit design experience) of no electronic component that can simply replace a mechanical relay (without understanding the behaviour of the circuit in which the substitution is imagined to take place).

Is the camera video output circuity (camera side of pins 6&11) understood to any extent that, for example, an externally connected photodiode (or amplifying phototransistor) is sufficiently reversed biased that on (associated optoisolator) LED light production the tiny reverse saturation current increases sufficiently to "short" pin 6&11 in a fashion functionally equivalent to a relay?
« Last Edit: 19 / June / 2018, 16:50:49 by andrew.stephens.754365 »


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Offline reyalp

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Re: analog video detect as a remote input
« Reply #4 on: 20 / June / 2018, 00:10:48 »
I'm not up to speed on either yet but don't wish to hold back with the following query - does Point 1 above infer pin 6&11 must be closed by a physical relay, similarly to:
You should just need to close the circuit. Transistors would seem preferable to relays.

I bought a sacrificial AVC-DC400ST clone on amazon to test.
The detect pin seems to provide somewhat below battery voltage (on elph180 ~3.2 when camera vbatt and a voltmeter across the battery shows 3.77) and passes something like 0.05 ma. It just needs to be connected to camera ground (e.g the connector shell), not specifically the other pin in the connector.

Looking at achilies page again, I noticed it mentioned camremote cables. Sure enough https://vp-systems.eu/order_cr.html offers an 11 pin canon AV/usb splitter, though quite pricey. Some surgery would still be required to make the av detect switchable.

edit:
Image with +~3v pin indicated
« Last Edit: 20 / June / 2018, 03:06:14 by reyalp »
Don't forget what the H stands for.

Re: analog video detect as a remote input
« Reply #5 on: 21 / June / 2018, 11:38:07 »
Thanks for details and measurements - definitely worth considering this further.

I wonder if the camera is any better at sensing current change (rather than voltage)... anyway, if I ever do a crt stereo test will report back here.
« Last Edit: 21 / June / 2018, 16:30:49 by andrew.stephens.754365 »

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Offline reyalp

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Re: analog video detect as a remote input
« Reply #6 on: Today at 02:18:37 »
I tested sx160 (AA powered) with a multimeter. It showed ~1.7 volts, 0.02 mA. Voltage varied somewhat depending on camera battery voltage.
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