Communications; Usb Upload; Serial Communications - Canon Camera Hackers Manual

7.6

Communications

In this section, we will discuss the camera uplink to a PC as well as serial
communication with an external device.

7.6.1 USB upload

Because the USB port, by default, is reserved for the remote control, you
must explicitly disable the option
Download if you want to upload (or download, depending on your angle of
view) images onto a PC. Of course, the camera must be switched to Replay
mode when uploading images.
The SDM upload functions are designed to work closely together with
the WIA Loader (www.mortara.org/index.php/software/windows/49-wia-
loader), a Windows (.NET) based image uploader. (On Linux and MacOS X, it
can run under the Mono-Framework 2.4.) The WIA Loader can, for example,
take care of stereo image pairs from twin cameras (section 7.7.4). It can
rename such images, place them in left and right folders, and rotate im-
ages losslessly if one camera is mounted upside down in a Z-frame.
Because transmission takes place through the USB port, the card can
remain in the camera. This has advantages in that the camera doesn't need
to be removed from an elaborate set-up and that the card is never forgot-
ten in the computer. The WIA loader can even automatically remove trans-
mitted images from the card. Because the SDM allows uploading images
via script commands (section 7.9), you can (almost) simulate tethered
shooting—at least for time-lapse operation. After an image has been
taken, the interval between two pictures can be used to upload the image
to the connected PC. And because the WIA loader can also delete the image
from the card, it never runs out of capacity.

7.6.2 Serial communications

Not only can the SDM communicate with a PC, it also offers the possibility
of using the blue LED as an optical serial port. A light-sensitive cell glued to
this LED and connected to a microcontroller (or to the sound card of a PC) is
all the hardware required for receiving data from the camera. A set of script
commands (section 7.9) is available to initialize the interface and to send
data to the connected external device. The device can even acknowledge
the successful reception by sending a signal to the V+ pin (supply voltage)
of the camera's USB port
must be enabled). This is not absolutely necessary but leads to more reli-
able communication.
ALT > MENU
(ALT > MENU > Scripting
> Scripting > Disable USB
> Disable USB Download
7.6 Communications
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