Canon Camera, Руководство хакера

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5.7 Example scripts
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The last (and optional) clause controls the display:
f
I switches to the info display.
f
N switches to the normal display (no info).
f D switches the display off to save power.
Lines that start with two dashes ( -- ) are considered as comments and are
printed to the display. Here are a few examples for script files:
-- Example
F 0 D
1:0 10 15
A 5:0 10 15-5
This schedule file results in the following actions:
1. “Example” is printed to the display.
2. The first shot in the schedule is taken immediately. The camera is fo-
cused before the shot and the focus is locked. The display is switched
dark.
3. After one minute, the camera takes 10 shots with an interval of 15 sec-
onds between shots.
4. Finally, at MET 00:05:00, the camera switches back to autofocus and
takes another 10 shots starting with an interval of 15 seconds and end-
ing with an interval of 5 seconds.
Now let’s analyze the script and see how it works. It uses some elements
that we developed already in the previous two scripts, such as file brows-
ing, display mode switching, and exact timing. What is new here is reading
file content and parsing (interpreting) that content. Basically, this is a script
that reads and executes a script (the schedule file).
The header defines the script title. The schedule files are expected in
folder
A/CHDK/SCHED
. The function
idiv()
implements integer division and
is used instead of the standard division in order to achieve compatibility
with the PC version of
Lua . The following pcall() expression is the connec-
tion to the debug environment on the PC (section 5.8).
--[[
@title Scheduled timeseries
--]]
schedules = "A/CHDK/SCHED"
function idiv(a,b)
return (a-(a%b))/b
end