Gesendet: Montag, 15. Juli 2013 um 04:43 Uhr
Von: "Gerard Toonstra" <address@hidden>
An: address@hidden
Betreff: [Paparazzi-devel] Adding "OFF" functionality to dc_cam to be able to retract lens on CHDK.
Hi there,
I've got a new setup in the works for Paparazzi in combination with a TechPod and a Canon camera.
One of the things I wanted is lens retraction prior to landing. Unfortunately it seems that only the camera "ON" message is implemented.
I could add a servo and hatch to protect the cam, but this adds weight.
In my CHDK script I intend to have two functions based on the length of the pulse. Because paparazzi uses quartersecs,
the idea is to output a 250ms pulse for shooting and probably a 750ms pulse for turning the camera off. This will then retract the lens.
Following are some ideas how I intend to implement this and submit. Comments are welcome.
1. The "POWER_LED" in the configuration refers to a LED to turn the cam on. Since this is a binary switch, it's probably not a good idea
to reuse the same for the power off function. So my intention is to add a "POWEROFF_LED", which in this case can be configured to
the same number as the "SHUTTER_LED".
2. Add another define called DC_POWEROFF_DELAY, which dictates the quartersec period for the poweroff message.
3. The GS or a flightplan sends a "DC_OFF" message, which is sent to the appropriate module (in this case led_cam_ctrl).
This will initiate the pulse on the poweroff_led and also set the dc_timer to the dc_poweroff_delay.
Caveat: To function correctly, the flightplan needs to turn off the autoshoot feature, such that the autoshoot doesn't interrupt the pulse.
This can be done at the end of the survey grid, or the start of the landing approach if the grid is canceled.
In the final approach the DC_OFF can then be sent.
( I don't think commands can be queued, which would allow for delaying the DC_OFF a bit until a (potentially) active autoshoot is finished ).
Rgds,
Gerard