building usb-remote-cable

[Microfunguy]

I just want to make sure that 6V isn't going to kill my camera.

People will say that the USB specification is +5V, but that is actually irrelevant for our purpose.

The USB V+ is connected to a resistor that goes to the base of a dual-transistor switch before connecting to the DIGIC processor.

On my A620, that resistor is 20K so the current is one quarter of a thousandth of an amp !

Assuming other cameras are similar, 6V is fine.

If you have access to a multimeter you can measure the resistance between the outer pins of the USB connector.

DO NOT user the audible continuity range of the meter !


David

[Cythrelo]

Thanks! I feel much less nervous now, and I just about have the remote together, so I'm about to give it a shot.

I do have a multimeter, but the contacts are way too big to fit in the little USB port of the camera.

[jetzt]

Well I usally also like current limiting instead of voltage limiting, but in that case two cheap resistors
could do a voltage divider and would be much safer. (Perhaps not electrically, but for nervousity.)

(Really simple: http://de.wikipedia.org/wiki/Spannungsteiler
or:
)

[JB]

Greetings from (another) Newbie!

Can anyone confirm whether or not the A720 is able to be activated (ie, as if the power button had been pressed) via a USB remote? The CameraFeatures - CHDK Wiki page lists 5-6V OK/Wake-Up: Yes, and when the camera is powered up the remote happily shoots photos for me, but a 5V input does not seem to be able to turn the camera on.

I've read & searched & googled for the last few days to try to find an answer, with no success. I am looking to set up some remote time-lapse stations, solar powered, taking only 2 or 3 photos each day, so just using an intervalometer script & leaving the camera powered on is not really an option.

If the A720 cannot support this capability, any other suggestions for a different model at the 'consumer' end of the Canon range which may support this feature would be gratefully received!!

Thanks for your time,

JB.

PS - and my supreme admiration for everyone who has contributed to the CHDK project... such amazing things you are accomplishing!

[jetzt]

@JB

CameraFeatures - CHDK Wiki page lists 5-6V OK/Wake-Up:

Perhaps there is a fault? Or another camera revision?
If there are five volts, for a few seconds, and there is no reaction you camera actually doesn't power up...

I have however the hardware solution for you, if you "wake-up" your camera already, I assume you have some electronics there,too. So why not mod the power switch?
I've soldered some wires to the switches of my old camera, not sure about canon, but if you do be aware of the flash capacitor,
discharging is useful...

Not as reliable but also possible is pressing the switch with a servo like most KAP rigs do.

[JB]

Thanks jetzt - yeah, hard-wiring the power switch is my fall-back option. I pulled the cover off the camera last night to discover that the wires to the on/off switch are TINY!! They're basically flexible printed circuit wires, and I don't know that I want to try soldering new wires onto those...

I'm just exploring posibilities right now, as I'll need to set up 10 of these things, so if I there's another camera that I could use which DOES power up via the USB port, that would be my preferred option. I will however check out the servo rigs you mentioned, as that is probably a viable third option.

Cheers

JB

[PhyrePhoX]

i know for a fact that my s3is does power up when theres is voltage on the usb port. the a620 does NOT.

[jetzt]

Thanks jetzt ......

I'm just exploring posibilities right now, as I'll need to set up 10 of these things, so if I there's another camera that I could use which DOES power up via the USB port, that would be my preferred option. I will however check out the servo rigs you mentioned, as that is probably a viable third option.

Cheers

JB

Nothing to thank for, I just wrote up the options I thought of when I wanted to build my "remote measurement station".
I further thought of an mega8(cause of easy programming) with some relays and temperature sensors,
the only missing part was the communication between camera and microcontroller.

Anyway I'm interested in your project, would you mind writing some more words about it?
Also when you have results?
Would be really interesting, how I already said,
jetzt

[JB]

Hi jetzt,

I work for a Government department in Australia responsible for the maintenance & control of a large surface water drainage network. We have a VERY large work area (over 12,000 square km!), and there many monitoring sites which I visit on a weekly or monthly basis. We also have 9 or 10 sites which are quite remote & hard to access in Winter, which are monitored remotely via solar-powered logging stations. It is at these sites that we'd like to install cameras which would take 2-3 photos a day, so that we can show the physical results of the yearly weather cycle in a time-lapse movie.

I've got the script quite happliy taking a photo & shutting down the camera, but the problem is starting it up in the first place. The logging station can output 5V or 12V signals whenever it's told to via it's own scripting, so I'd hoped to use a remote cable as described in this thread to turn the camera on. Unfortunately that doesn't seem to be supported for the A720IS. Without going up to the S3/S5 cameras (budget limitations), it looks like the SD870 (IXUS860) might be another option for us, as the Camera Features page shows that this camera does support the wake up function. Mind you, that table shows that the A720 does as well...  Can anyone else confirm/deny this for the IXUS860? We're quite happy to look into other cameras, but the scripting functionality of CHDK makes life SO much easier for me!

BTW, I have no formal/technical qualifications, so hopefully I don't ask any stupid questions while I'm here!! I enjoy solving problems, so this little project landed in my lap. Always happy to learn though!!

JB

[fe50]

Hello & welcome JB !

I'm a SD870 (Ixus 860) user, made some tests for you & here are the results:

- USB remote is working when the camera is powered on
- the Script Autostart is working, i.e. on power-on the selected script automatically starts
- the camera DO NOT power-on when the USB is plugged in !

The wikia entry (CameraFeatures chart) is ambiguous, "Wakes up on USB signal?" on the SD870 means that the USB remote functionality is working well when the camera is already powerd on. (Maybe i'll edit this...)

The SD870 also do NOT power-on when the battery is inserted / the battery door get closed.

The only possibillity (without soldering cables to the cameras power switch or using a mechanical solution) could be the following:

When the camera is powered-on and then the battery door is opened and closed again, the camera start & runs the script.
The camera remembers the last operating state (in this case power-on) and start when the door is closed again.
For this no USB remote is necessary, a simple script could do it - but if the camera once is powered-off regularly it do not power-on again when the door is opened / closed...

So i think this will not be a solution for you...

I also own a Ixus 50 (SD400), not sure whether it is the same - can do a test this evening...

[JB]

Hello again!

Thanks for the info everyone, it's been great to get such quick responses. I believe that I have found a different solution to my problem, which makes my previous questions redundant... sorry about that!! :blush:

I will set up a solenoid trigger like the one described here: http://home.vicnet.net.au/~vic3d/pentax_rig.html. (Scroll down to 'Shutter Firing System', just over half-way down the page). This one is designed to trigger the shutter, however I will use the same mechanism to press my power on/off switch. Without testing, I figure that a pulse of about half a second from the logger to the solenoid should depress the power button long enough to switch the camera on. When the power stops, the solenoid will release, allowing the script to tell the camera to take a photo, then shut down. Program the logger to power up the solenoid 2-3 times a day, and we've got what we want!

Unfortunately, while digging around in the camera today, I've short-circuited something & it won't even power up, so I'll have to send it away for repairs. Oh well, I have to order the solenoids anyway so I guess it's no great problem...

Once I have some more parts to play with, I'll get started on the construction & keep you posted on how it's going!

Thanks again,

JB.

[jetzt]

... I will set up a solenoid trigger like the one described here: ...

Ah he finally decided to take the hardware solution. I think you should add some photoresistor infront of an led, so you can be sure if the camera has really been on.

I've short-circuited something & it won't even power up

Ah, I warned you, don't press the battery pads to the connections of the flashcapacitor! 

Thanks for the description
jetzt

[toinech]

The only possibillity (without soldering cables to the cameras power switch or using a mechanical solution) could be the following:

When the camera is powered-on and then the battery door is opened and closed again, the camera start & runs the script.
The camera remembers the last operating state (in this case power-on) and start when the door is closed again.
For this no USB remote is necessary, a simple script could do it - but if the camera once is powered-off regularly it do not power-on again when the door is opened / closed...

Would it be an option to use the external power cable instead of opening or closing the battery door?
A timer will feed the power long enough for the camera to run a script to take a picture then power off before the cam autoshut off.

[fe50]

The only possibillity (without soldering cables to the cameras power switch or using a mechanical solution) could be the following:

When the camera is powered-on and then the battery door is opened and closed again, the camera start & runs the script.
The camera remembers the last operating state (in this case power-on) and start when the door is closed again.
For this no USB remote is necessary, a simple script could do it - but if the camera once is powered-off regularly it do not power-on again when the door is opened / closed...

Would it be an option to use the external power cable instead of opening or closing the battery door?
A timer will feed the power long enough for the camera to run a script to take a picture then power off before the cam autoshut off.

No, not an option on the Ixus 860 (SD870)...
The Ixus series use a battery dummy to connect to external power (ACK-DC30), the cable is plugged in in this dummy (through a hole in the middle of the door). Plugging off the external power is the same as removing the battery, the camera forgets the former state ("door opened while camera was on") and do NOT start when getting power again..

[acorrias]

Hi all,
i've made my first wired remote control (a 7805 stabilizer, a led with a resistance, a button and a 9v battery). Plus a plastic box and a usb mini B cable. My problem is that the only way to take shoots seems to be the use of the following script:
^^^^^^^^^^^^^
@title Remote button
while 1
  wait_click 1
  if is_key "remote" then shoot
wend
end
^^^^^^^^^^^^^
>>>>Is there any other way? and what about the Script Page setting called "Enable remote USB"? how can I use it and how can I start script different from the one above?
>>>>Another problem seems to be the shoot latency: it takes 0,5 sec to start a shot after button press. Is it a normal thing?
Could you tell your experience about remote control and suggest how to optimize this tricky tool?
thanks in advance
Alex