Mindboards

Hey all,

I was wondering if it is possible to connect the USB from the NXT to a camera device to control it. In the specific case I'm thinking of a Canon EOS series camera.

Since in a USB protocol there's always a host and a the endpoint, I imagine this is a difficult thing (or impossible?). Both devices are endpoints, right? Is there any possible way to make the NXT act as a host?

Thanks for any help!

PS: Digging into Canon protocol is still an open question for me as well... but a step at a time.

NXT USB port is a USB slave, unfortunately.
You might try to build an i2c- or RS485-USB-hostadapter, although I admit this is not my personal speciality...

It can be done from a sensor port using I2C or from a motor port using relays (one if you just want shutter control, two if you also want to set the focus).

Mindsensors relay driver can be used to control both, as can the module from Techno-stuff.

http://www.mindsensors.com/index.php?mo ... AGE_id=140

http://www.techno-stuff.com/relay.htm

If you want to build your own you need one 9v relay and one rectifying diode (1N4001) for each function.
You can also use a transistor as a relay.

http://www.mapageweb.umontreal.ca/cousi ... rial2.html

You did not specify which EOS you were using but this applies to the 'consumer' versions. I believe the more expensive models work the same way but using a different connector.

http://martybugs.net/photography/remote.cgi

Thanks a lot for the schemes, h-g-t!

My electronic skills are not the best, but this seems to be quite easy. I will try to build it my self, instead of buying mindsensors' relay or technostuff one. Just because it increases the cost. If the cost is reasonable, I design a little PCB.

Indeed, I've heard a bit about this 3-pin feature to control the shutter and the focus. I was looking for something more advance. I'm not the camera expert, this is a project to work for a friend of mine, but he says the control of those two things would be enough for our creation.

The camera will probably be a 7D.

Cheers!

It can be difficult to get the right connector for a 7D. Probably easiest to get a wired remote from ebay (as little as £2.38) then either replace the remote switch with a 3.5mm stereo audio plug or wire a 3.5mm stereo socket into the remote. Using the latter method means you can still use the remote normally if you want.

Connector details here - http://www.doc-diy.net/photo/remote_pinout/