Digital camera control using Arduino USB Host Shield. Part 2 – Canon EOS Cameras.

New version of PTP Library for Arduino USB Host Shield has been posted on GitHub. In this version, PTP::Task() has been completely rewritten to provide for non-blocking state machine-type execution. Another major addition is comprehensive support for Canon EOS cameras – many camera functions including changes of shooting parameters, Live View, focus move, are now well understood and supported. The library is released under GNU General Public License version 2.

In addition to the code library, a manual page has been created outlining EOS-specific extensions to PTP protocol, a code example, and library reference. Similar page for basic PTP functions is planned also.

The code is stable (more or less) and no application interface changes are planned at this moment. It is, however, incompatible with an old version, which is preserved in “legacy” branch of GitHub repo. The camera interface has not changed much and migration of old projects should be easy. If you have issues with migration, comment below and I will try to help.


Digital camera control from Arduino-hosted webpage

I found this little video while looking for ideas for my digital camera controller. There is also project description and summary page. Device consists of Arduino board mated with Asynclabs WiShield controlling shutter release of SLR camera via cable release port. Arduino runs TCP/IP stack and Web server while access to pre-focus, time interval and other settings is done via web browser on an iPod. In addition, it is possible to release shutter using signal from proximity sensor or even set conditions based on states of different Arduino pins.

The web interface is well designed – watch this little movie and see it for yourself. There is also a demo page, where you can play with controller functions. The “Adm” page is my favourite. I’m looking forward to see the code, which author is going to publish soon.

Digital camera control using Arduino USB Host Shield. Part 1 – basics.

Arduino taking picture of itself

Arduino taking picture of itself

I’m starting new series of articles describing exciting field of digital camera control. In modern cameras, USB port can be used not only for transferring images to a PC, but also for sending control commands to the camera. It is often possible to send commands which “press” the shutter button, modify shutter and aperture values, some cameras are even capable of doing focus control. At the same time, new shooting techniques, such as HDR and stacked focus, require that a photographer makes several shots, slightly modifying one or several shooting parameters from shot to shot. Even age-old time lapse technique could use some automation. Since camera manufacturers are, as always slow to implement there cool features, Arduino comes to the rescue.

I am announcing new code developed for Arduino USB Host shield which implements digital camera control functions via PTP. Alex Glushchenko, a developer from my native Russia, recently joined camera control project and code shown here and in the future articles is mainly his. He did most of reverse engineering and code development and my contributions to this project were mainly code testing, camera borrowing, and blogging. Code is hosted on github separately from USB Host library. Be warned – this source is preliminary and will be changed many times before it becomes stable! It is also expected to grow quite a bit – different cameras use different commands and developing universal code supporting all manufacturers (or even every camera from one manufacturer) is not possible due to the modest resources of Arduino platform. Therefore, several libraries have been developed, each covering specific set of cameras. The cameras supporting functions of a certain library are listed in library’s header file. The list of cameras is currently quite small but I’m hoping to get more cameras supported in the future.

Digital camera as USB peripheral is much more complex and less standard than a keyboard. The complexity starts at the very first level – device configuration. Very often , several different configurations are supported on a device and the default configuration is not the one we need. Therefore, the first step would naturally be learning how to recognize configuration which supports camera control commands.

There are 3 specifications describing USB digital camera works. Still Image Device specifies USB requests, descriptors and endpoints. The protocol structure is described in Media Transfer Protocol (MTP), which is better known by its previous name, “Picture Transfer Protocol” (PTP). The most interesting document, which actually lists commands supported by camera class, is known as “PIMA 15740-2000”. It is available for a fee from I3A, however, second-hand pdf copy can be obtained for free after some googling. Camera manufacturers implement their own functions, expanding PIMA definitions. In addition to that, some older cameras use their proprietary protocols instead of PTP; support for such cameras will be added eventually.

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