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DIY USB Bulb Trigger?

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#1 jeffpkamp

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Posted 26 September 2013 - 10:16 PM

I know there are plenty of computer savy folk who frequent this site. I was wondering if anyone has made a DIY page for a USB camera trigger.

I made myself the Serial camera trigger, which I use with a USB>serial converter, but I was wondering why not cut out the middle man and just use the usb. I know it can be done, I mean that's what the DSUSB from shoestring astronomy is right?

I'm not terribly familiar with USB operation, but it seems that if you can run a fan on a USB port you can open your shutter, and you just need a program to either turn the USB port on and off, or even better a way to just turn the voltage on or off for the port.

Does any one have any ideas or suggestions? This would be useful to a lot of people I think and it would save me having to use the stupid knock off USB>serial I bought :)

#2 Edward E

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Posted 27 September 2013 - 10:01 AM

I have a Canon SX210 point and shoot using the CHDK firmware which allows the camera to be triggered by a USB signal. No programing required; just press a button for a second or two and the camera takes a photo. This is the electronic equivalent to the old analog shutter cable.

I have just built the trigger using a small 12 volt, remote "garage door" opener battery, a USB cable with the mini "B" connector, a press button switch, a 4.7 volt 1W zener diode and a 100 ohm resistor, battery holder, small project box, plastic film canister and some wire. The zener diode acts as a voltage regulator and limits the voltage to the camera's USB to no more than 5.1 volts which is with the specs of USB 2. The film canister holds the button switch and is a perfect fit for my hand. The project box holds the battery and other components. Works great on the bench will give it a field test Saturday night. I can get some photos of the project posted here later if you would be interested.

I am also working on a IR remote version of this trigger but still working out the math on it.

There is the web link to the CHDK page for USB triggers:
CHDK Remote

#3 jeffpkamp

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Posted 27 September 2013 - 10:14 AM

Just to make it clear, I am talking about a long exposure trigger that could be run by the computer (ie something like DSLR shutter). I am thinking about this for my nikon d5100 which uses the GPS/9 Pin port to do bulb functions. Unfortunetly they didn't do the bulb via usb until d5200 :(.

After reading a little bit about USB, it seems that it would be bit like the Serial bulb trigger program. The USB VBUS would provided the normal voltage, and you could use the D+ to provide the signal to a transistor to open or close, allowing for triggering.

What I am not sure about is how to make a program recognize a USB cable plugged into a port (I assume most have some sort of chip to get recognized), and how to send a constant signal down the V+ line.

I feel like you should be able to hack something like a old USB thumb drive for recognition and then have a program made to send that drive a constant signal...

#4 Raginar

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Posted 27 September 2013 - 07:34 PM

Get dusb from shoestring Astonomy. It costs about 90 bucks and just works.

#5 groz

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Posted 27 September 2013 - 10:18 PM

Off a serial pot it easy, it's a level trigger on a control line. USB doesn't have control lines, so a USB interface to a microchip is used, and a gpio on the chip is used. It's not dumb gle logic.

The cheapest way to get a level trigger from a USB port is still to use a serial USB converter. They are produced in such volume, a complete unit costs less than the bits required to build a USB interface.

#6 ccs_hello

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Posted 27 September 2013 - 10:26 PM

Easy DIY solution is to use a USB-to-RS232 serial converter dongle, connecting to a simply electronics (opto isolator as relay) to camera's shutter cable.
Basically, RTS lead, if active, is the shutter trigger. Tie DTR and CTS leads together (some software use this to verify the cable in there.)

There are many USB-RS232 serial cablez to choose from. FTDI is the golden standard (about $14 shipped). Some recent PL2303 based seems to be stable now (and Win7/8 driver is available). It's less than $5 shipped from China or Hong Kong.

The simple electronics DIY plan is here:
http://www.beskeen.c...ABLE - NIKON...

Clear Skies!

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#7 jeffpkamp

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Posted 30 September 2013 - 08:53 AM

I have already done the usb serial trigger. I guess the usb route is a little trickier than I thought it'd be. I feel like it is more of a programming issue than a hardware issue to make it work. I destroyed an old mouse with a usb connection (well just took the case off). I can't imagine that you couldn't hijack it's driver (This mouse is so old it has its own) to send a signal. Then again I am a microbiologist, and not a programmer, so maybe it's a little harder than I might think :).

If my programmer friend and I come up with something ground breaking I'll let you guys know. Ha.

#8 ccs_hello

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Posted 02 October 2013 - 07:16 AM

$9 solution using USB-GPIO MCP2200 chip:
(so long as astro programs would support the MCP2200 based solution)
http://microcontroll...roducts_id=4173

There are other USB-GPIO solution, but the above link is the cheapest I can find.

There are other "cooked" (controlled by command strings) USB-relay solutions. They can be found in fleabay for $10-$20. But again, the issue is "so long as astro programs would support the (new command language) solution".

Clear Skies!

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#9 jeffpkamp

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Posted 03 October 2013 - 08:58 AM

thanks CCS. Every one I talk to says just do the usb to serial. While it looks like legit USB>serial converters bottom out at about $9, the board you showed me would be much more convienent than trying to solder onto the pins of the serial port I got from radio shack. I'll keep looking.

#10 groz

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Posted 03 October 2013 - 02:41 PM

Dont solder onto the pins, solder onto a db9 connector which fits the cheapie usb-serial gadget.

#11 ccs_hello

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Posted 03 April 2014 - 12:29 AM

2014 my new DIY version:
http://www.cloudynig...&Number=6444568

Easy and cheap.

Clear Skies!

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