[extras] Add CHDK script to work with digital_cam module

closes #480

sw/extras/chdk/pictuav.lua

@@ -0,0 +1,168 @@
+--[[
+@title PictUAV
+@param d Display off frame 0=never
+@default d 0
+--]]
+
+-- Developed on IXUS 230 HS. Other cameras should work as well, but some errors or crashes are possible
+-- also considering that some firmwares still have CHDK bugs.
+--
+-- Other settings in the camera that you should try to manipulate to reduce the time between taking pictures:
+-- CHDK menu
+--   Extra Photo overrides
+--     Disable overrides : Off
+--   Do not override shutter speed  ( I allow the camera to determine exposure time, but feel free to experiment)
+--   ND filter state: Out (removes ND filter to allow more light to fall on the sensor )
+--   Override subj. dist. value: 65535. (good to keep it there)
+--   Do not save RAW images, they take longer
+--   
+-- Camera menu
+--   Use P mode, certainly not automatic
+--   If you can hardset the focus, do this towards infinity
+--   Play around with aperture. Smaller apertures are better for more sharpness, but not every camera allows you to.
+--      (Some cameras have really bad behaviour on larger apertures that allow more light through, especially at edges).
+--   Disable IS  (plane vibrations mess up its function and increases the chance of blur)
+--   Take Large images with Fine resolution.
+--   Turn "Review" mode off.
+--   Consider hard-setting ISO, but consider local weather. If set too high, shutter time goes up, which causes blur. 
+--     Blur can then also occur in areas where there is little light reflection from the earth.
+--   
+--   How to use the script:
+--     Load this on the card under "CHDK/SCRIPTS"
+--     Enter the CHDK menu through your "ALT" button
+--     Under scripts, select the script and specify "Autostart: on"
+--
+--   As the camera starts up, this also loads. with the shutter button pressed, you can interrupt the script
+--   Then press the "ALT" button to disable the scripting actuator. 
+--   Press the shutter button to extend the lens
+--   Press "ALT" again to bring up the scripting actuator.
+--   Press the shutter button to reinitiate the script.
+--   If you have a IXUS 230HS like me, the focus can't be set automatically. Point the camera at a distant object while the script 
+--   is starting. It should say "Focused", after which it's ready for use.
+--
+--   Example paparazzi airframe configuration:
+--
+--    <section name="DIGITAL_CAMERA" prefix="DC_">
+--      <define name="AUTOSHOOT_QUARTERSEC_PERIOD" value="8" unit="quarter_second"/>
+--      <define name="AUTOSHOOT_METER_GRID" value="60" unit="meter"/>
+--      <define name="SHUTTER_DELAY" value="0" unit="quarter_second"/>
+--      <define name="POWER_OFF_DELAY" value="3" unit="quarter_second"/>
+--    </section>
+--
+--    <load name="digital_cam.xml" >
+--      <define name="DC_SHUTTER_LED" value="4"/>
+--      <define name="DC_POWER_OFF_LED" value="4"/>
+--      <define name="DC_RELEASE" value="LED_ON" />  
+--      <define name="DC_PUSH" value="LED_OFF" />
+--    </load>
+--
+
+print( "PictUAV Started " )
+
+function print_status (frame)
+   local free = get_jpg_count()
+   print("#" .. frame )
+end
+
+-- switch to autofocus mode, pre-focus, then go to manual focus mode (locking focus there).
+-- this helps to reduce the delay between the signal and taking the picture.
+function pre_focus()
+   local focused = false
+   local try = 1
+   while not focused and try <= 5 do
+      print("Pre-focus attempt " .. try)
+      press("shoot_half")
+      sleep(2000)
+      if get_prop(18) > 0 then
+	 print("Focused")
+	 focused = true
+	 set_aflock(1)
+      end
+      release("shoot_half")
+      sleep(500)
+      try = try + 1
+   end
+   return focused
+end
+
+-- set aperture/shooting mode to landscape
+set_prop(6,3)
+
+ap = get_prop(6)
+print ("AF(3=inf,4=MF) "..ap)
+
+-- Turn IS off
+set_prop(145, 3)
+
+-- set P mode
+set_capture_mode(2)
+sleep(1000)
+
+-- Get focusing mode
+p = get_prop(6)
+if (p==3) then
+	print "Inf set."
+else
+	-- on ixus230hs, no explicit MF. 
+	-- so set to infinity (3)
+	while (p ~= 3) do
+		press "left"
+		release "left"
+		p = get_prop (6)
+	end
+	print "Focus set to infinity"
+end
+
+-- on ixus230hs set focus doesn't fail, but doesn't do anything.
+set_focus(100)
+print "set_focus 100"
+sleep(2000)
+f = get_focus
+
+-- on ixus230hs set focus doesn't fail, but doesn't do anything.
+set_focus( 65535 )
+print "set_focus 65535"
+sleep( 2000)
+g = get_focus
+
+if (f==g) then 
+	print "set_focus inop"
+	-- if focusing until here didn't work, pre-focus using a different method.
+	pre_focus()
+else
+	-- set_aflock(1) fails when the camera isn't knowingly focused.
+	print( "Setting aflock 1" )
+	sleep(1000)
+	set_aflock( 1 )
+end
+
+-- measuring the pulse on CHDK isn't necessarily that accurate, they can easily vary by 40ms.
+-- Since I'm using a 100ms wait here, the variance for a shoot is around 140ms. 
+-- If the pulse is 250ms, then I should allow for anything down to 110.
+-- For Paparazzi, taking a single picture using the button may not work because the timing may be very off
+-- considering the 4Hz loop (this requires a change in the cam module for paparazzi).
+
+print( "PictUAV loop " )
+a = -1
+repeat
+	a = get_usb_power(0)
+	-- a pulse is detected longer than ~610ms.
+	if (a>61) then
+	        print( "shutting down " )
+		shut_down()
+		sleep(1500)
+		break
+	end
+	-- a pulse longer than ~100ms is detected.
+	if (a>10) then
+
+	   frame = 1
+	   shoot()
+
+	   frame = frame + 1
+
+	end
+	sleep(100)
+until ( false )
+print( "PictUAV ended " )
+