Lua

LUA Scripting language for CHDK

...this is work in process...

The CHDK allows you to automate your camera by running "scripts", small and simple programs written in a short-hand version of BASIC, named "UBASIC".

Additionally to this an alternative scripting language named "LUA" is available in some of the latest experimental builds [NEW - Exceptional Builds from the CHDK Forum].

So what is Lua?

Lua is a powerful, fast, light-weight, embeddable scripting language. Lua combines simple procedural syntax with powerful data description constructs based on associative arrays and extensible semantics. Lua is dynamically typed, runs by interpreting bytecode for a register-based virtual machine, and has automatic memory management with incremental garbage collection, making it ideal for configuration, scripting, and rapid prototyping. Lua is Open Source software, its licenses are compatible with GPL. (quoted from www.lua.org)

For Developers: LUA is brought to CHDK by "Velo" in the forum in April 2008: Lua Scripting Integration

A first LUA sample script:

for i = 1,10 do
  print( "Picture "..i )
  shoot()
  sleep( 2000 )
end

Running LUA scripts

• A CHDK version with build-in LUA support is needed, e.g. the "the collaborative CHDK build"
• The script should be saved with the filename extension .lua in the CHDK script folder
• Loading, starting, pausing & stopping works the same way as on UBASIC scripts
• UBASIC scipts are also working as usual, the filename extension (.lua or .bas) tell CHDK how to run the script

Links

• The programming language Lua - Homepage

NEWS

Reference Manuals

License

LUA sample scripts

yet another accurate intervalometer

--[[
rem 20080805
@title yet another accurate intervalometer
@param a Duration (min)/-1 disable
@default a -1
@param b Duration (sec)/n of seqs
@default b 5
@param c Delay 1st sequence (min)
@default c 0
@param d Delay 1st sequence (sec)
@default d 3
@param e Trigger every n min
@default e 0
@param f ...every n sec
@default f 3
@param g ...every .n sec
@default g 0
@param h Endless?
@default h 0
@param i Seq dur (m)/-1
@default i -1
@param j Seq dur (s)/n of shots/seq
@default j 1
]]

drivemode_continuous = 1

if a < -1 then a = -1 end
if ( a > -1 and b < 0 ) then b = 0 end
if ( a == -1 and b < 1 ) then b = 1 end
if c < 0 then c = 0 end
if d < 0 then d = 0 end
if e < 0 then e = 0 end
if f < 0 then f = 0 end
if g < 0 then g = 0 end
if ( h < 0 or h > 1 ) then h = 0 end
if i < -1 then i = -1 end
if ( i > -1 and j < 0 ) then j = 0 end
if ( i == -1 and j < 1 ) then j = 1 end
if (( i == -1 and j > 1 ) or i > -1 ) then
  if get_drive_mode() ~= drivemode_continuous then
    print( "set drive mode" )
    print( "to continuous" )
    sleep(1500)
    cannot_continue = true
  end
end

if a > -1 then duration = a*60000 + b*1000 else duration = b end
delay_first= c*60000 + d*1000
if g < 0 then delay = e*60000 + f*1000 + g*10 else delay = e*60000 + f*1000 + g*100 end
if i > -1 then sequence = i*60000 + j*1000 else sequence = j end


function shoot_by_numbers( sequence_target )
sequence_current = 0
repeat
  tick_target = get_tick_count() + delay
  sequence_current = sequence_current + 1
  print( "sequence " .. sequence_current .. " of " .. sequence_target )
  if i == -1 then shoot_count( sequence ) else shoot_tick( sequence ) end
  while ( get_tick_count() < tick_target and sequence_current < sequence_target ) do
  end
until sequence_current >= sequence_target
end

function shoot_by_duration( duration )
duration_target = get_tick_count() + duration
repeat
  tick_target = get_tick_count() + delay
  if i == -1 then shoot_count( sequence ) else shoot_tick( sequence ) end
  print( (duration_target-get_tick_count())/1000 .. " sec to go" )
  while ( get_tick_count() < tick_target and get_tick_count() < duration_target ) do
  end
until get_tick_count() >= duration_target
end

function shoot_forever()
tick_initial = get_tick_count()
sequence_current = 0
repeat
  tick_target = get_tick_count() + delay
  sequence_current = sequence_current + 1
  print( "sequence " .. sequence_current )
  if i == -1 then shoot_count( sequence ) else shoot_tick( sequence ) end
  print ( (get_tick_count()-tick_initial)/1000 .. " sec elapsed")
  while ( get_tick_count() < tick_target ) do
  end
until false
end

function shoot_count( count_inc )
count_target = get_exp_count() + count_inc
if count_target > 9999 then count_target = count_target - 9999 end
press( "shoot_half" )
press( "shoot_full" )
repeat
until get_exp_count() == count_target
release( "shoot_full" )
repeat
until get_shooting() == false
end

function shoot_tick( tick_duration )
tick_target = get_tick_count() + tick_duration
press( "shoot_half" )
press( "shoot_full" )
while ( get_tick_count() < tick_target ) do
end
release( "shoot_full" )
repeat
until get_shooting() == false
end

if not cannot_continue then
  tick_target = get_tick_count() + delay_first
  print( "waiting " .. delay_first/1000 .. " sec" )
  while ( get_tick_count() < tick_target ) do
    tick_current = get_tick_count()
  end
  if h == 1 then shoot_forever() end
  if a > -1 then shoot_by_duration( duration ) else shoot_by_numbers( duration ) end
end