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Simple, embedded USB host for digital camera control

Hello, World!

I want to remotely control a digital camera (Canon Powershot S60, and maybe others) for use in aerial photography (with kites, blimps, etc.)

*SHORT STORY* =============

Any suggestions of how I can do this via USB? Do you think it is feasible with an Atmel AT90USB1287? Or would I need a AT43USB380, or other? For me, the simpler the better...

*LONG STORY* ============

I can send radio commands to a controller connected to the camera and trigger it (with a servo motor, IR emitter, USB host, ...) , but I also want control over the camera settings. A USB host seems to be the best solution, as:

- A single servo motor can be used for triggering, but not much else. Several could be used to access other buttons, but this would be a kludge (not to mention the added weight, which is a serious issue for me).

- The camera's IR port is used only for a couple of functions (you can't change settings like ISO, exposure, etc. this way). I could try to implement IR access to more functions if I had a firmware to hack, but AFAIK, there's no firmware dump available for neither this nor several other Canon models...

- I could open the camera and wire connections to simulate the pressing of all buttons on the camera body. It would probably work, but it's not an elegant solution to say the least (and I don't want to void any camera warranty if possible).

Another good points for a remote control via USB:

  • Canon have a PC remote control software via USB for the camera, and it works great: you have total control over all camera settings.

  • I could sniff the USB data from that program, but the Canon USB protocol was already reversed engineered and documented by the folks who wrote a Linux driver for it.

I have some experience with electronics, but I'm really a programmer (C / assembly on several platforms). I'm already reading the USB specs and some Atmel datasheets, but I'd love to read the opinions of someone who already underwent a similar project.

Thank you!

Reply to
Ric
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I'm actually considering doing the exact same thing (for the exact same purpose !).

I've looked at the AT90USB1287 and it seems like it would do the job. The Atmel USBKey evaluation circuit is only $30 so I bought one in the hopes of finding the time to experiment with this part. The most daunting aspect is the implementation of the proprietary Canon USB protocol (even though most of the hard work has already been done by the Linux driver guys).

Scott

Reply to
Scott

I assume you will not be too upset if you lose this camera in a hard landing, or that you need the resolution or other capability that a $20 digital (or even several of them with different focal lengths to replace the zoom function) wouldn't give you in a lower mass.

Apparently, being a USB host is a lot harder than being a client (or whatever terminology is used in the USB world). And the microcontrollers are host only.

(I could be wrong about this.)

A servo pushing the button is probably harder than wiring a remotely operated switch to the trigger release, given that you're a programmer. (Who stereotypically would merely destroy anything he tried to modify electronically, but would cause himself gross bodily harm trying to do anything mechanical.)

--
David M. Palmer  dmpalmer@email.com (formerly @clark.net, @ematic.com)
Reply to
David M. Palmer

The terminology is host/device which is essentially master/slave, as the host/master is responsible for directing the communication over the bus.

A USB host software stack is non-trivial, but I have heard of others doing a minimal implementation that may work for static one-host-one-device systems. If you are so inclined, usb.org is your friend for documentation.

--
Michael N. Moran           (h) 770 516 7918
5009 Old Field Ct.         (c) 678 521 5460
Kennesaw, GA, USA 30144    http://mnmoran.org

"So often times it happens, that we live our lives in chains
  and we never even know we have the key."
The Eagles, "Already Gone"

The Beatles were wrong: 1 & 1 & 1 is 1
Reply to
Michael N. Moran

I'm someone that has created his own minimal USB host stack, in this case for a UHCI controller.

In my case, it's a one host to multiple device setup, but because the exact devices are known, I was able to use a static configuration table for the USB network.

However, it's still quite a bit of work to write even a minimal USB host stack and I would not recommend it unless the person attempting this is very familiar with system/kernel level programming concepts.

I had a quick look at the AT90USB64/128 datasheet and it appears that things have been simplified in this controller, but it appears there's still quite a bit of the housekeeping to do that you would have to do in a stack for a more general purpose controller. Does Atmel provide a sample USB host stack for it's microcontrollers ?

BTW, I briefly considered porting the Linux or FreeBSD USB stacks, but decided that it was just as easy to write my own minimal stack (and as it was part of a embedded hobbyist project, much more fun. :-) )

Before buying hardware, the OP (if he has not done it already) should read through his intended USB host controller datasheets, the usb.org documents and the datasheets for his intended USB device(s) in order to get an idea of how much work is involved.

Simon.

PS: And before anyone asks, no, my code is not available. :-)

--
Simon Clubley, clubley@remove_me.eisner.decus.org-Earth.UFP
If Google's motto is "don't be evil", then how did we get Google Groups 2 ?
Reply to
Simon Clubley

Actually, I want to usa a Canon camera (hardly $20), and I would be very upset if I loose it! I already did several KAP sessions and got several hundreds of pictures in total, with about a hundred of excellent or very good ones.

The implementation of a USB host is more complex than the implementation of a USB device (aka USB function), but the Atmel AT90USB1287 is a "USB On-The-Go (OTG) Microcontroller".

Reply to
Ric

I need to control just one exact device, so there's even (a bit) less work.

Some software is available for the AT90USBKey demonstration board on Atmel's site, but I'm still waiting for a reply from them to be able to check the sources (they are on ZIP archives with passwords).

That's where I am right now.

Ouch! :-(

Not even with a pretty pretty please, with lots of sugar on top? I can change the sugar for Xylitol, if you want...

Reply to
Ric

Hello.

I'm sorry, but although the code works just fine, the documentation (and to a lesser extent, the code) would need a significant cleanup before it would be something that I would be comfortable releasing. The code is also tied closely to the UHCI controller specification and my requirements. Don't forget that this was a hobbyist project, not something intended for public release.

There's also the fact that you would need to learn the USB 1.1 specifications to understand the code anyway, at which point you are probably better off looking at something like the FreeBSD USB code base to resolve any remaining questions.

If you don't have access to a FreeBSD system, then the FreeBSD source code is available in cvsweb format at the FreeBSD website. I suggest that you start at

formatting link
if you are interested in looking at it.

Simon.

--
Simon Clubley, clubley@remove_me.eisner.decus.org-Earth.UFP
If Google's motto is "don't be evil", then how did we get Google Groups 2 ?
Reply to
Simon Clubley

"Simon Clubley" skrev i meddelandet news: snipped-for-privacy@eisner.encompasserve.org...

Yes. The AT43USB380 will be simpler to use though, since the complete host stack is running on chip, and it presents a high level API to the micro. Basically, no need to know anything about USB.

The U-boot boot monitor has a USB stack which can access USB Mass Storage devices.

--
Best Regards,
Ulf Samuelsson
This is intended to be my personal opinion which may,
or may not be shared by my employer Atmel Nordic AB
Reply to
Ulf Samuelsson

But is this true for the AT90USB family? I couldn't find any USB host stack sample on Atmel's web site (I only found sample sources for USB devices)...

Is such stack available upon request?

OTOH, the AT90USBKey is much more affordable than the AT43DK380 dev. kit... ;-) And the AT43USB380 seems to be a bit overkill for my application.

Reply to
Ric

I did something like that with a cheap pencam usb camera. But the USB stuff is overkill. I simply opened the camera and made an external connection to the camera buttons. My setup simply used a micro to "press the buttons" every 30 or 60 seconds. After bringing the kite down I transfer the images to a laptop over USB.

There are older type digital cameras that also have a serial interface (option), but these tend to be on the heavy side to get them airborne when there is not a lot of wind.

Joop

Reply to
Joop

At first, I was also planning to do the same, but I want good quality images and resolution, using a good compact camera (or even a SLR). And I really don't want to void warranty nor deface a good looking, expensive camera. ;-)

[]s!
Reply to
Ric

The other thing you can do is use the Canon remote control. A quick search shows it can be had for $30. You could rig the buttons on this remote. Then your camera is still in one piece.

Reply to
Joop

It was my first idea, but the remote control is very limited. As I stated previously, I don't want just a triggering system. With Canon's remote control you can't change shooting parameters as I want to (on some camera/remote models you can't even control the zoom)...

[]s!
Reply to
Ric

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