DIY USB Bulb Trigger?
Posted 26 September 2013 - 10:16 PM
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
Posted 27 September 2013 - 10:01 AM
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:
Posted 27 September 2013 - 10:14 AM
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...
Posted 27 September 2013 - 07:34 PM
Posted 27 September 2013 - 10:18 PM
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.
Posted 27 September 2013 - 10:26 PM
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...
Posted 30 September 2013 - 08:53 AM
If my programmer friend and I come up with something ground breaking I'll let you guys know. Ha.
Posted 02 October 2013 - 07:16 AM
(so long as astro programs would support the MCP2200 based solution)
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".
Posted 03 October 2013 - 08:58 AM
Posted 03 October 2013 - 02:41 PM