Canon Camera Hackers Manual page 238

Data transmission-related commands
enable_usb_download
disable_usb_download
By default, USB download (upload) is disabled, so that the camera can react to a USB
remote control. By enabling the USB upload and switching to Playback mode, a peer
program running on a PC (such as the WIA loader) will start and open a connection.
make_usb_connection
Switches to Playback mode and opens a USB connection for upload.
break_usb_connection
Closes the USB connection and switches back to Record mode. The peer program on
the PC must have already closed the connection.
upload_images_for t
Switches to Playback mode and opens a USB connection for the specified time. Then it
closes the USB connection and returns to Record mode. Can be used in combination
with the WIA loader (section 7.6) for uploading images at regular intervals.
unit_pulse
Generates a single pulse on the
external device (section 7.6).
send_data a, b, c
Sends three bytes of data to an external device by flashing the
7.6). The external device acknowledges the correct reception by sending a signal to
the USB V+ pin. The values a, b, and c should be in the range of 0.255.
data_received a
Used after send_data to wait for an acknowledgement by the external device on the
USB port. Waits for 100 msec and returns 1 if a signal is received at the USB V+ pin
within that time. Returns 0 otherwise.
LED and sound-related commands
af_led_off
af_led_on
Identical to set_led 9, 0 and set_led 9, 1. (section 5.5.8). Be careful with the
af_led_on command—the AF LED is probably not built to be illuminated for a long
period of time.
blink_af_led_for t
Blinks the AF LED for the specified time t (seconds). Typically used for kite aerial
photography ( KAP) because the AF LED can be seen from some distance.
blue_led_off
blue_led_on
Identical to set_led 8, 0 and set_led 8, 1 (section 5.5.8).
PRINT LED. Typically used to calibrate the connected
PRINT LED (section
229
7.9 Scripting