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  • This is work in process... Fe50 11:07, December 28, 2010 (UTC)

See also the Scripting Cross Reference Page for the complete list of CHDK scripting commands for Lua and uBASIC. And also see: http://chdk.wikia.com/wiki/Script_commands and http://chdk.wikia.com/wiki/UBASIC/Scripts and http://chdk.wikia.com/wiki/Lua/Lua_Reference .

Starting out[]

Keep these things in mind when writing your scripts:

  • Scripts may conflict with your camera if it is set to its fully automatic state. If you are having problems try setting your camera into "P" mode. When CHDK is not loaded: press the cam/movie button then the right button until P is highlighted and press SET. Also consider setting your camera to a fixed ISO value instead of AutoISO. When CHDK is not loaded: press the SET button, then scroll up to the top and right to a fixed ISO value.
  • Use a plain text editor to compose your scripts. Make sure it saves the file as TEXT-ONLY. Do NOT use programs like Word, wordpad or other advanced editors. These insert hidden header info and use non-standard ASCII characters for Return/Line-Feed commands, quotation marks, and others. The simplest of text editors will suffice (Notepad in Windows, nano in Linux for example). Scripts must be saved as ASCII plain text. UTF-8 may work, but is not recommended because some editors insert a unicode BOM at the start. Mac users see this special note concerning Macs and Script Files.
  • Keep all commands in lower-case. Variables are, however,  case-sensitive (a and A are not the same).
  • Be aware that not all commands work on all cameras. If you plan on sharing your script try to keep it as generic as possible unless you have a special need for the camera-specific commands. Try to also provide a more generic version so that all may benefit from it.
  • Keep your script concise and efficient! It takes 10ms of time for each line of script to be interpreted by tiny uBASIC. A script 10 lines long takes 1/10th of a second, 100 lines takes a full second, etc. This can greatly impact high-speed uses.
  • If you write an interesting script, share it with the rest of us at User Written Scripts so we may learn from you! Beginner script writers can be some of the most creative! Also if you are just starting out use the page for ideas and examples.
  • Have a look at the settings in the scripting menu, there are some interesting features available such as autostart, parameter sets & more...


The Script Header[]

At the start of each uBASIC or Lua script is a script header section.  The script header section allows you to define the script's name,  identify which version(s) of CHDK are compatible, insert any comments or user notes needed,  and define "user parameter variables" that can be set at script run time from the CHDK Script menu.   Documentation for the script header can be found here : CHDK Script Header


The Basics of CHDK scripting[]

Note : Most of the descriptions and examples on this page are based on the uBASIC syntax. In uBASIC most commands expect parameters separated from the command with a space char. Strings are indicate with the use of quotation marks. In Lua the parameters are written in parentheses, directly after the command.

Sample:

print "Shoot"         (uBASIC syntax)
print("Shoot")        (Lua syntax)

Links to a detailed documentation of the Lua language can be found on the Lua main page.

Logic Commands for uBasic[]

All programs are designed to mindlessly repeat some commands. In order to make them work in the proper order, and the correct number of sequences, they have to be contained in some simple recurring loops and counters. Testing for when some condition has been met, before it can go onto the next command, or finally end the program (script).

There are several ways this can be done in uBASIC. By using numeric counters, and loops.


The LET Command[]

This one is simple. If you see a command that says "let a = 2" then that's exactly what happens. It defines the value of 2 to the variable a.
This command is mostly included just for legibility. You can leave off the let command and it will still work. Example: let a=2 can be written more simply as a=2. Or this example: if z>5 then let b=0 can be simplified to if z>5 then b=0. Doing so will greatly save on script space if you have to define and redefine many variables many times.


The IF / THEN / ELSE Commands[]

These are used to test for the truth of a certain condition. IF something is true, THEN this takes place, ELSE (otherwise) do this if it is not true.
A simple example:
if a > 2 then goto "subroutine1"
If in your script, the variable a has been assigned to a value greater-than 2, then the script will jump to the labeled subroutine1.
if a >2 then goto "subroutine1" else goto "subroutine2"
In this case if a is NOT greater than the value of 2, your program will jump to subroutine2.
The conditional expressions allowed in uBASIC are: = (equal to), > (greater than), < (less than), <> (not equal to), <= (less than or equal to), >= (greater than or equal to)


IF / THEN / ELSE / ENDIF - Multiple Statements[]

Fingalo reports: "Seems to have some bug when not using the else in nested if constructs!"

Usage:

if relation then
statement
statement
statement
...
else
statement
statement
statement
...
endif

The standard single-statement if...then...else... loop still works, but it cannot be used inside the if...then...else...endif loops.

NOTE: nesting levels for all loop methods are currently set to 4 for all new constructs.


The FOR / TO / NEXT Commands[]

These are used to set up simple loops. You will often see them in scripts as in this example:
for n=2 to a
    sleep t
    print "Shoot", n, "of", a
    shoot
next n
The first line "for n=2 to a" means that the "for / to / next" loop will run while variable-n equals the sequence of numbers of 2 up to whatever the number variable-a has been assigned to. The commands that take place in the loop are containted between the FOR statement and the NEXT statment. "next n" tells the loop to go back to the beginning "for ..." statement until the the a value has been reached.

For example:

for n=1 to 10
   print "This is line number", n
next n

This will produce the sequence of:

This is line number 1
This is line number 2
This is line number 3
.
.
.
This is line number 9
This is line number 10

And then that loop will end and go onto the next sequence of commands.


FOR / TO / STEP / NEXT Loops[]

A standard BASIC step command was added to the for/to/next commands make loops easier. Instead of using multiple lines for counters to increment numeric expressions with commands like a=a+1 or b=b-3, a simple next command may now be used.

Usage:

for var=expr to expr step expr
statement
statement
statement
...
next var

Where var can be any variable, expr can be any defined variable or math expression, and step can be any defined variable or math expression. The step value may also be negative to increment in reverse.

Example:

@title Focus Bracket Steps
@param d Near Focus (mm)
@default d 2500
@param e Far Focus (mm)
@default e 4500
@param f Step Increment (mm)
@default f 100

for x=d to e step f
set_focus x
shoot
next x

end

If using the default values this simple script will start out at the Near Focus value of 2500mm, increment that value by 100mm every time, shoot an image, and exit when the focus has reached or passed 4500mm.


Subroutines using GOSUB (and related GOTO) Commands and Labels[]

Sub-Routines[]

For complex programming tasks, it is often helpful to split the program into smaller subroutines that can be called with gosub and goto commands. A sub-routine can be nearly anything but it is generally used for a set of commands that will be called-up more than once. Instead of writing the same set of commands over and over again you put that code into a subroutine and then call it up from within the main program by using gosub "label" or goto "label". Subroutines are generally placed after the main code. A labeled subroutine that will be called by gosub "label" needs to end with the return comand, to tell the script to jump out of that section of code and return back to from where it was called.
GOSUB and GOTO are similar but you should refrain from using GOTO unless you know what you are doing. GOSUB will always return from a subroutine as soon as it reaches the RETURN command. GOTO does not behave this way. GOTO should only be used when you are going to jump to a section of the script one time and under special circumstances.


GOSUB and GOTO Examples[]

A simple GOSUB example (the subroutine's label and subroutine are in bold):
for x=1 to 10
  gosub "display"
next x

:display 
  print x
  return
A longer example that would capture three images with increased ISO settings would look something like this:
shoot    
for i=1 to 3    
  gosub "incISO"    
  shoot    
next i    
for i=1 to 3    
  gosub "decISO"    
next i    
end    
:incISO    
  click "menu"    
  [some more clicks]    
  return    
:decISO    
  click "menu"    
  [some more clicks]    
  return
An example using the GOTO command taken from an endless intervalometer script. NOTE: This situation creates an endless loop. Until you manually override, the script it will continue. This is generally considered BAD FORM! Any script should include/end-with all the commands to reset the camera to its original configuration prior to running the script, and properly end with the END command. Do not do this kind of thing, unless you have a special need for it and know what you are doing.
@title Interval Shooting Non-stop 
@param a Interval (Minutes) 
@default a 0 
@param b Interval (Seconds) 
@default b 5 
@param c Interval (10th Seconds) 
@default c 0 

t=a*60000+b*1000+c*100 

if t<100 then let t=5000 

n=1 

print "Interval shooting."
print "Until you interrupt it."
print "Use with caution."

sleep 1000 

:shot
  print "Shot number", n
  shoot
  n=n+1
  sleep t
  goto "shot"


Do / Until Loops[]

Another method of creating loops for repetitive instructions or when waiting for some condition to be true. Code inside a Do/Until loop will always be executed at least once (unlike While/Wend loops)

Usage:

do
statement
statement
statement
...
until relation

Where relation may be any logical expression. If it is ever true, the loop will exit.

Example:

rem set some starting values for the variables
y=0
x=5

rem start do-loop

do

rem increment x by 10 each time
x=x+10

rem increment y by 1 each time
y=y+1

rem print results to viewfinder mini-console
print "This DO loop happened", y; "times."

rem repeating do-loop until x is equal to the value of 55
until x=55

end


While / Wend Loops[]

Similar to the DO / UNTIL loops. The loop will continue to execute while some statement remains true, and will end, wend (while-end), when that statement is no longer true. Unlike Do/Until loops, code within a While/Wend loop may never be run, if the test condition is already false when the While statement is first reached.

Usage:

while relation
statement
statement
statement
...
wend

Example:

x=0
while x<200
x=x+25
print "The value of x is", x
wend

This loop will increment the value of x by 25 each time and print the value of x, as long as (while) the variable x remains less than 200


rem[]

The "rem" (which stands for "remark") command is sometimes used to place a comments in a script. It is only used as a reminder for the person writing or viewing the script, like an internal note. This command is not executed nor seen when the script is run. However, keep in mind that scripts for CHDK can be only 8,192 characters in length (only 2,048 in CHDK before build #119). Too many REM statements can slow down a script as well as taking up valuable space.
An (overzealous) example of REM commands in a script
rem Interval shooting

@title Interval shooting
@param a Shoot count
@default a 10
@param b Interval (Minutes)
@default b 0
@param c Interval (Seconds)
@default c 10

rem Calculate 1000ths of seconds from variables

t=b*60000+c*1000

rem Sets some default variables to initial values
if a<2 then let a=10
if t<1000 then let t=1000

rem Print total duration of session in viewfinder

print "Total time:", t*a/60000; "min", t*a%60000/1000; "sec"

rem Delay actual shooting so they can read the above print statement.

sleep 1000

rem Start actual camera operation in a loop

print "Shoot 1 of", a
shoot
for n=2 to a
    sleep t
    print "Shoot", n, "of", a
    rem This takes the actual exposure.
    shoot
next n

rem Ends this script

end
REM statements can always be removed from a script if you feel there are too many or unneeded. Removing a rem line will not impact the operation of the script in any way (other than speeding it up and using up less memory space).

Math Expressions in uBASIC[]

+   Addition
-   Subtraction
*   Multiplication
/   Division
%   Remainder (explanation see below)
<   Less Than
>   Greater Than
=   Equal
<=  Less Than or Equal   (CHDK Build #144 or later)
>=  Greater Than or Equal   (CHDK Build #144 or later)
<>  Not Equal   (CHDK Build #144 or later)
&   And
|   Or
^   Xor


Most of the expressions are easy to understand, but the % (remainder) operation might like a short explanation.

Example: Let's say you have computed a number to equal how many seconds something will take for a duration. Such as s=(some math expression) Where s is being assigned the number of seconds computed.
In math it's called "modulo".
Now you want to display that as minutes and seconds. You will need a print statement such as:
print "Total Time:" , s/60; "min", (the remainder of s/60); "sec"
There is a very simple way to do this using the % command. Think of % as "the remainder of s being divided by". So all you need to do is have this print statement:
print "Total Time:" , s/60; "min", s%60; "sec"
If s had the value of 328 seconds, then this would print out to
Total Time: (328/60)=5 min (the remainder of 328/60)=28 sec
or more simply
Total Time: 5 min 28 sec

Some further notes:

<   Less Than
>   Greater Than
=   Equal
<=  Less Than or Equal
>=  Greater Than or Equal
<>  Not Equal

are relational operators.


&   bitwise and
|   bitwise or
^   bitwise xor

are bitwise operators, not logical operators. The logical operators and, or, and not were added to CHDK build #144. Examples of the use of &, |, and ^ bitwise operators are:

e=5|3
print e

will print "7".
5&3 returns "1".
5^3 returns "6".
For an explanation refer to bitwise operators


Logical Operators: AND, OR, NOT in uBASIC[]

not	logical not (best used with parentheses i.e. not (expression)
and	logical and
or	logical or

Priority for evaluation order has been updated so expressions like

if a=1 or b=3 and c>4 or d<>7 then ...

are being correctly calculated, although it would be preferable to use parentheses to understand what is being calculated when.

Also priority for "&" and "|" has been changed the same way.

NOTE: Multiple relational operators are allowed.



Common scripting commands[]

print[]

This prints whatever text follows the statement, to your LCD or EVF display in the mini-console area (see firmware usage) while the script is running.
Syntax: print "25 characters of text"
The display limit for any one line of text is 25 characters. Variables or integer equations can be included in a print statement.
Examples:
rem Print total duration of interval to viewfinder

print "Total time:", t*a/60000; "min", t*a%60000/1000; "sec"

sleep 1000

rem Start actual camera operation in a loop

print "Shoot 1 of", a
shoot
for n=2 to a
    sleep t
    print "Shoot", n, "of", a
    shoot
next n
Note that the comma (,) is replaced in the output with a space while a semicolon (;) results in no whitespace
Example:
print "C","H","D","K"
print "C";"H";"D";"K"
Will result in
C H D K
CHDK


print_screen[]

The print_screen function enables/disables logging to a file a copy of print statements to the mini-console screen.

uBASIC :

To enable file logging, call print_screen with a non-zero value. This will create a log file in the /CHDK/LOGS directory with name LOG_nnnn.TXT, where nnnn is the absolute value of the parameter you passed to the print_screen statement.

If the passed value is negative, the log will append to the end of the exiting log file. If the passed value is positive, the old file will be overwritten. If the passed value is zero, the logging will be disabled.


Example:


@title uBASIC Printscreen Test 
@param a None 
@default a 0 
set_console_layout 0 0 45 12
print "uBASIC : this is not written to a file" 
print_screen 5
print "uBASIC : this is written to file LOG_0005.TXT" 
print "a="a 
print "done"
print_screen 0 
print "This is not written to file" 
print_screen -5
print "This is written at the end of LOG_0005.TXT" 
print_screen 0
end

Lua

To enable file logging, call print_screen() with a non-zero value. This will create a log file in the /CHDK/LOG directory with name LOG_nnnn.TXT, where nnnn is the absolute value of the parameter you passed to the print_screen statement.

If the passed value is less than 0, the log will append to the end of the exiting log file. If the passed value is greater than  0, the old file will be overwritten. If the passed value is a 0 or boolean false, logging will be disabled. If the passed value is a boolean true, a new log file LOG_0001.TXT will be created.

Example:


--[[
@title Lua Printscreen Test 
@param a None 
@default a 0
--]]
set_console_layout(0,0,45,12)
print("Lua : this is not written to a file" )
print_screen(5) 
print("Lua : this is written to the file LOG_0005.TXT")
print("a=",a)
print("done") 
print_screen(false) 
print "This is not written to a file" 
print_screen(-5)
print "This is written to the end of file LOG_0005.TXT" 
print_screen(false)

cls[]

cls stands for "Clear Screen". This is used to clear the mini-console screen from any "print" statements in an easy way. Instead of having to issue 5 command lines of print " ", you just need to issue this one small cls command.


Sleep[]

This pauses the script to allow some action to take place, or to delay when the next action should occur.
Syntax: sleep x
Where x is any variable or whole number. The value is in 1000ths of a second.
Example: sleep 1500 means to pause for 1.5 seconds.


exit_alt[]

This command causes a CHDK script to leave <Alt> mode while running. Note that the uBASIC version of this command expects a single parameter (which is not used). The correct uBASIC syntax is
  exit_alt 0

enter_alt[]

This command causes a CHDK script to re-enter <Alt> mode while running (typically after having used the exit_alt() function). 

Note that the uBASIC version of this command expects a single parameter (which is not used). The correct uBASIC syntax is

  enter_alt 0

get_alt_mode[]

This command returns the current ALT state. This can be used to by a script so that it does not attempt to read button pushes or to update the LCD when the CHDK has left ALT mode while the script is still running (possibly because the user pressed the ALT key).

Lua : function returns true if CHDK is currently in ALT mode and false otherwise.

uBasic : function return 1 if CHDK is currently in ALT mode and 0 otherwise.

end[]

This should be the last line of every uBASICC script. It tells the script to cease all operations and return camera control back to you. Before ending a script, it is good-form to always reset any camera settings that the script took control of during initialization of your routine or during. So that the end user doesn't have to undo all the keypresses and menu changes that the script created.


Motion Detection[]

Note 1: There has been much discussion on the proper ways to use this sometimes-confusing and highly adaptable and user-configurable feature. A lengthy discussion on the new CHDK Forum on how to get the fastest reaction times for lightning photography has shed some light on the subject (pun not intended). For further clarification on the best ways to implement some of the timing controls, see this post in the "Motion Detection Too Slow?" discussion thread. Which also includes a script optimized to obtain the fastest detection speed possible by using 2 different methods (both available in the same script). The MD routine has been reworked for some cameras so the internal "immediate shoot" option is now lightning-fast (literally). This change will probably be added to all new future builds (note added 2008-02-07 c.e.).
Note 2: Hints and tips for usage have been scattered all over the net, a new "Motion Detection Settings" page was created to try to assemble some of the best tips. If you can add to it or help clarify it, please do so. The page linked in the strike-out comment is wholly irrelevant as-is. The info there was taken out of context from another post discussing a script that uses the md-routine, and has no information about the md command itself. A good idea poorly implemented. If you would still like to create a more concise and clear explanation of all of the md parameters and usage, with sample script explanations, feel free to use that page, Delete everything on it if you have to and start from scratch. Otherwise, don't even bother reading it, it's useless as is. Its existence only creates more confusion the way it stands now and is subject for complete deletion. [mr.anon]

Available Commands


md_detect_motion[]

This command is the main brunt of setting all feature parameters.

                 /--/-COLUMNS, ROWS to split picture into
                 |  |
                 |  |  MEASURE MODE (Y,U,V R,G,B) - U=0, Y=1, V=2, R=3, G=4, B=5
                 |  |  |
                 |  |  |  TIMEOUT
                 |  |  |  |
                 |  |  |  |  COMPARISON INTERVAL (msec)
                 |  |  |  |  |
                 |  |  |  |  |  THRESHOLD ( difference in cell to trigger detection)
                 |  |  |  |  |  |
                 |  |  |  |  |  |  DRAW GRID ((0=no, 1=grid, 2=sensitivity readout, 3=sensitivity readout & grid))
                 |  |  |  |  |  |  |
                 |  |  |  |  |  |  |  RETURN VARIABLE number of cells with motion detected
                 |  |  |  |  |  |  |  |
                 |  |  |  |  |  |  |  |           OPTIONAL PARAMETERS:
                 |  |  |  |  |  |  |  |
                 |  |  |  |  |  |  |  |  REGION (masking) mode: 0-no regions, 1-include,
                 |  |  |  |  |  |  |  |  |      2-exclude
                 |  |  |  |  |  |  |  |  |
                 |  |  |  |  |  |  |  |  |  REGION FIRST COLUMN
                 |  |  |  |  |  |  |  |  |  |
                 |  |  |  |  |  |  |  |  |  |  REGION FIRST ROW
                 |  |  |  |  |  |  |  |  |  |  |
                 |  |  |  |  |  |  |  |  |  |  |  REGION LAST COLUM
                 |  |  |  |  |  |  |  |  |  |  |  |
                 |  |  |  |  |  |  |  |  |  |  |  |  REGION LAST ROW
                 |  |  |  |  |  |  |  |  |  |  |  |  |
                 |  |  |  |  |  |  |  |  |  |  |  |  |  PARAMETERS: 1-make immediate shoot,
                 |  |  |  |  |  |  |  |  |  |  |  |  |  |   2-log debug information into file (* see note below!),
                 |  |  |  |  |  |  |  |  |  |  |  |  |  |   4-dump liveview image from RAM to a file,
                 |  |  |  |  |  |  |  |  |  |  |  |  |  |   8-on immediate shoot, don't release shutter.
                 |  |  |  |  |  |  |  |  |  |  |  |  |  |   OR-ed values are accepted, e.g. use 9 for
                 |  |  |  |  |  |  |  |  |  |  |  |  |  |   immediate shoot & don't release shutter
                 |  |  |  |  |  |  |  |  |  |  |  |  |  |
                 |  |  |  |  |  |  |  |  |  |  |  |  |  |  PIXELS STEP - Speed vs. Accuracy
                 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |    adjustments (1-use every pixel,
                 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |    2-use every second pixel, etc)
                 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
                 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  MILLISECONDS DELAY to begin
                 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |   triggering - can be useful
                 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |   for calibration with DRAW-
                 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |   GRID option.
md_detect_motion a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p

The minumum number of variables that must be set with this command are:

md_detect_motion a, b, c, d, e, f, g, h
Timeout: [mx3]it is time in milliseconds for which md_detect_motion will block execution of next ubasic commands if during this period no motion detected. this parameter is useful if you want to execute periodically some other ubasic commands together with MD.

i.e. MD routine waits for changes for 1 second. if no motion detected script can continue to execute some other code and then if required can resume motion detection by calling again md_detect_motion. so timeout is just time for which md routine will wait for changes. Practically, this TIMEOUT value (parameter d) shall be greater than the MILLISECONDS DELAY (parameter p), or else you will always get RETURN VARIABLE (parameter h)=0. (feel free to change this text to be better English)[/mx3]

Comparison Interval: The time delay in milliseconds in which to check for a change in a cell's values. If you need to filter out small changes made frequently by faster moving objects (leaves in the wind, or flying insects, for example) you would increase this value so that timed samples are further apart. Very useful when trying to detect changes in very slow moving subjects, i.e. snails, slime-molds, a slow-moving criminal trying to avoid motion detection devices :-), etc.
h - RETURNED VARIABLE: this variable must be used for decision whether you want to make shoot. it contains count of cells where change is more than specified threshold value.

example: if h>0 then shoot

n=2 (debug mode): Since build #684 (Jan 18th 2009), this debug feature has been removed to save RAM. To use it, a custom CHDK version must now be built (OPT_MD_DEBUG=1 in makefile.inc will enable motion detector debug).
(insert more information on variable parameter functions and uses as they become known or more familiar)

md_get_cell_diff[]

This function is for those people who want to know where on scene actually detection happened. This procedure is designed for scene change advanced analysis.

Usage: md_get_cell_diff (column), (row), x

where x will be difference of 0 to 255 between the last and present change in that cell. Triggering a script to shoot on this value may be done by detecting no change, or how much sensitivity you would like to detect in that cell.

Examples:
If you would like to have the camera shoot an image when all motion stops, use:
if x=0 then "shoot"
To shoot an image when any motion is detected at all use:
if x>0 then "shoot"


Interesting use of MD
The following was copied from a post where MX3 mentions a feature of md_get_cell_diff that was never documented before.
nobody tried to use MD to get overall luminosity to automatically
adjust shutter speed override?

MD setup:
set delay interval to 2-3 secs
timeout=delay_interval+1
threshold=255 (so it will not trigger ) 
cols=1
rows=1

md_get_cell_diff 1, 1, overall_luminocity

shutter_override_time = some_formulae ( overall_luminocity )

I don't have camera nearby to test it.

I have thought about timelapse movie script which would automatically override shutter speed at night. I'm planning to make 2 days timelapse
movie ( it seems 8gb SD card and power adapter will help also :-) )


NOTE: when MD stops working on timeout, cells containg absolute values instead of difference.
The most important info contained in that final "NOTE:".

Referring to the 'md_detect_motion' command-parameters in the WIKI article, 'a' and 'b' define the number of rows and columns to split the screen into. (If values less than zero are entered or if total number of cells is greater than 1024, it defaults to 3 x 3.)

Parameter 'g' determines if the grid showing the detected cells is displayed (0=no, 1=grid, 2=sensitivity readout, 3=sensitivity readout & grid)

Parameters 'j,k,l,m' define a sub-area of the screen where motion-detection is restricted-to or excluded-from.

Parameter 'i' determines if the region is inclusion/exclusion or do not use regions.

You may detect motion based on changes of luminance (Y), blue – luminance (U), red – luminance (V) or individual R, G or B values.

Parameter 'c' sets that mode.

( For an example of an image split into it's YUV components, see this WIKI article. )

For non-specialized use, luminance (c = 1) will be used.

You then need to set a threshold-value (in parameter 'f') for the desired mode that will not result in triggering in 'normal' operation.

The motion-detection event may be triggered by quick or slow changes in the screen image, set a suitable value with parameter 'e'.

The greatest accuracy of movement-detection results when every pixel is sampled but a faster response (suitable for some applications) may be obtained with a larger pixel-step.

Set an appropriate value in parameter 'o'.

Set a maximum-time for a motion-detection event to occur with parameter 'd' so that after that time the script-command terminates.


Motion-detection Parameters :

columns, // input parameter. number of columns to split screen into

rows, // input parameter. number of rows to split screen into

pixel_measure_mode, // input parameter. // 1 - for Y, // 2 for U, // 3 for V, // 4 for gray, // 5 for R, - // 6 for G, // 7 for B

detection_timeout, // input parameter. number of milliseconds to abort detection. detected_cells_count will be 0 for timeout condition

measure_interval, // input parameter. number of milliseconds between comparison of two pictures

threshold, // input parameter. difference value for which procedure will trigger detection of changes

draw_grid, // input parameter (0=no, 1=grid, 2=sensitivity readout, 3=sensitivity readout & grid)

detected_cells_count, // output parameter. count of cells where pixel values differs enough to trigger motion detection // clipping. allows to exclude some region from motion detection triggering // or use only selected area to make motion detection // I'm not sure that following parameters are required but using them anyway

clipping_region_mode, // input parameter. // 0 no clipping regions // 1 - for excluding selected region from motion detection // 2 - use this only region to make motion detection

clipping_region_column1, // input parameter.

clipping_region_row1, // input parameter. // this is top-left corner of clipping region

clipping_region_column2, // input parameter.

clipping_region_row2, // input parameter. // this is right bottom corner of clipping region)

function md_get_cell_diff ( col [in], // column of the cell we are requesting row [in], // row of the cell we are requesting val [out] // value of difference between measurements/comparisons)

reserved parameters clipping regions, pixel_measure_mode draw_grid



Camera Operation Commands[]

shoot[]

Records an image.
This command is similar to the click "shoot_full" command (see below), but it waits for the camera to perform some normally automatic actions, such as auto-focusing, charging the flash, etc. For example: if in AUTO, P, Tv, Av, or any SCN modes, using the "shoot" command causes the camera to check focus and exposure for each shot. When "shoot" is used in intervalometer scripts this far surpasses the camera's own built-in intervalometer in that the camera only sets exposure and focus once for the initial exposure, as if it was only using the "click 'shoot_full'" command. This "shoot" command in an intervalometer script allows it to compensate for all the things that can change over the course of many minutes and hours. For more precise manual control of the camera in scripts, see the click "shoot_half", click "shoot_full", when used in conjunction with the get_tv, set_tv, set_tv_rel, get_av, set_av, set_av_rel commands below.
Since revision 2529 (only CHDK 1.2) 'shoot' returns a control value.
0 - shoot ok
1 - shutter half press timed out (SD card full, etc)
2 - shoot failed (twice) after half press


Camera Button Commands[]

These commands are designed to allow your script to control your camera much like you would manually. Nearly anything you can do by pressing buttons on your camera with your own fingers, you can also do automatically with these script commands. The complexity and time-line of your script is only limited by your imagination.

Camera button commands can be written in 3 flavors / command-methods:

  • click "button-name"
Presses the button momentarily, used for one time, instantaneous commands. This will be the most often used method of issuing a camera command.
  • press "button-name"
Presses and HOLDS the required camera button, it remains pressed until the same button-name is given the release command. Some camera commands can only be accessed when a button is held down during use.
Example: In Manual Focus in the S-series cameras the MF button needs to be held down while the focus commands are being issued. Or when shooting in high-speed burst mode, then the shutter button must be held down during its needed duration with the press "shoot_full" command.
  • release "button-name"
Ends the press "button-name" command. If using a press "button-name" command be sure to end it with the release "SAME-button-name command at the appropriate sequence in your script to reset things back to normal.

All camera command buttons that you can press manually you may use in your scripts using this syntax. The only exception is the often-used shoot command. shoot is used by itself without the leading click, press, and release command methods.


All button-pressing commands (except shoot) should be written in the following syntax:

command-method "button-name"

Where command-method may be click, press, or release, and the button-name must be enclosed in double-quotes.


For example, a simple script using all 3 command-methods which makes AELock and AFLock on A-series cameras:

sleep 2000 
press "shoot_half" 
sleep 1000 
click "erase" 
click "down" 
release "shoot_half"


Possible Valid Button Names[]

The following is a list of button names recognized by CHDK. Note that one or more buttons are probably not available on any particular camera.

"up" "down" "left" "right" "set"
"mode" "shoot_half" "shoot_full" "shoot_full_only"1 "help"
"zoom_in" "zoom_out" "menu" "display" "print"
"erase" "iso" "flash" "mf" "macro"
"video" "timer" "expo_corr" "fe"2 "face"
"zoom_assist" "ae_lock" "metering_mode" "remote"3 "no_key"4

Notes :

  1. press "shoot_full" activates both shoot_full and shoot_half. To release just shoot_full, use release "shoot_full_only"
  2. "fe" = microphone
  3. "remote" = status of USB connector +5V pin
  4. "no_key" is returned if wait_click times out

click/press/release "up", "down", "left", "right"[]

Actuates the respective directional button of your "Omni-Selector" (navigational buttons).

click/press/release "set"[]

Actuates the set button.
Note: press and release would not normally be used with this button, but without knowing each and every camera model's functions and the creative ways some might use scripts, these two command-methods are also mentioned.
On the SX10IS, holding down SET causes a clock to fill the display. The clock appears after holding the button down for ~2 seconds and disappears about 5 seconds after releasing the button.

click/press/release "shoot_half"[]

Actuates the shutter-release in the half-press position. This is often used to lock focus, exposure, or other camera settings.
(Note: In dim light it can sometimes take up to 2+ seconds for a camera to hunt for focus. If your script is using this command to set auto-focus, and is designed for or intended to also be used in low-light conditions, it would be good to follow a press "shoot_half" command with a sleep x command, where x can have a value from 1500 to 2500.)

click/press/release "shoot_full"[]

Actuates the shutter-release button completely, regardless if the camera has finished charging the flash or other normally automatic camera operations.

click/press/release "shoot_full_only"[]

Actuates only the shutter-release button "full press" internal switch. This is mostly useful where a click "shoot half" has been previously used and you wish to hold the focus and exposure locked. Doing a release "shoot_full_only" will then simulate only letting the shutter button up to the half-press position (whereas a release "shoot_full" simulates letting the shutter button return fully to the off position). (for more info, see this forum thread )

click/press/release "zoom_in", "zoom_out"[]

Initiates your camera's zoom control one zoom-step at a time. (It is uncertain at this time (I didn't test it), how this will act using the press and release commands.) The A-Series cameras have 9 or 15 zoom steps (0 to 8/14), and the S-series cameras have 129 zoom steps (0 to 128). This command may require an extra sleep command after each zoom step. When using click the S-series cameras implement this command very slowly. Here's an example of how it may be used in a loop:
for s=2 to a
    for n=1 to b
        print "Zooming-in ", n; "..."
        click "zoom_in"
        sleep 600
    next n

    print "Shoot", s, "of", a
    shoot
next s
Note the 0.6 second sleep command after each zoom_in step.

click/press/release "menu"[]

Actuates the menu button.
This is used to alter some of the cameras settings that can only be set through the record menus, to set up the camera before a script-session, or during.
Note: press and release would not normally be used with this button, but without knowing each and every camera model's functions and the creative ways some might use scripts, these two command-methods are also mentioned.
Example:
:slowsync 
  click "menu"
  sleep 400
  click "down"
  sleep 400
  click "down"
  sleep 400
  click "down"
  sleep 400 
  click "right"
  sleep 400
  click "menu"
  sleep 400
return
This :slowsync" sub-routine will initialize the camera's flash setting into slow-sync mode. Note also the sleep commands, giving your camera time to respond to the new settings between each directional button-press. Button-press delay times may be camera specific. (Meaning it might be a good idea to set up a user-defined variable for these in some scripts to save on script-size and make the script more adaptable to more makes and models of cameras. A note could be made in the accompanying script's documentation on what button-press delays are needed per make and model of camera.)

click/press/release "display"[]

Actuates the camera's display button.
Note: press and release would not normally be used with this button, but without knowing each and every camera model's functions and the creative ways some might use scripts, these two command-methods are also mentioned.

click/press/release "print"[]

Actuates the camera's print button. (Note: actuates the shortcut button for S-series cameras.)
Note: press and release would not normally be used with this button, but without knowing each and every camera model's functions and the creative ways some might use scripts, these two command-methods are also mentioned.

click/press/release "erase"[]

Actuates the camera's erase button. (Note: actuates the FUNC (function) button for S-series cameras.)
This will often be used to select some shooting parameters like exposure-compensation, movie frame-rates, white-balance settings, ... any of the options that can be reached by pressing this button on your camera. It is then used in conjunction with directional button-presses to choose the desired settings.
Note: press and release would not normally be used with this button, but without knowing each and every camera model's functions and the creative ways some might use scripts, these two command-methods are also mentioned.
Example:
@title EXP bracketing 
@param a Number of +/- steps 
@default a 2
@param b Step size (1/3EV)
@default b 3

if a<1 then let a=2
if b<1 then let b=3

sleep 1000

print "Preparing..."
click "erase"
for n=1 to a*b
    click "left"
next n

for s=1 to a*2
    print "Shoot", s, "of", a*2+1
    shoot
    for n=1 to b
        click "right"
    next n
next s

print "Shoot", a*2+1, "of", a*2+1
shoot

print "Finalizing..."
for n=1 to a*b
    click "left"
next n
click "erase"

end
In this "Exposure Bracketing" script, if you follow the embedded button-presses, you'll see that your Exposure Compensation setting is being selected by using the click "erase" command. The click "right" and click "left" commands are moving the Exposure compensation settings to the right and left (more exposure and less exposure), just as you would if you were doing this manually from one shot to the next.

click/press/release "iso", "flash", "mf", "macro", "video", "timer" (S-series only)[]

Actuates the S-series specific buttons.

is_pressed "key"[]

checks if the specified key is being pressed when the command is called,  returns 1 for true,  0 for false

A listing of valid key names is available here :  Valid Button Names

Example :

s = is_pressed "menu"

is_key[]

checks if the specified key was pressed (used after a wait_click),  returns 1 for true,  0 for false

if is_key "set" then goto "continue" 

or

k = is_key "set"

A listing of valid key names is available here :  Valid Button Names

wait_click[]

Syntax

wait_click timeout (waits for any button is clicked; timeout is optional)
x =is_key  "button-name" (if last clicked key was "button-name" then x=1 otherwise x=0 ;  for timeout checking "no_key" should be used as the button name)

Example :

...
:loop
  wait_click 5000

  k = is_key "left"
    if k=1 then gosub "k_left"
  k = is_key "right"
    if k=1 then gosub "k_right"
  k = is_key "set"
    if k=1 then gosub "k_set"
  k = is_key "no_key"
    if k=1 then goto "timeout"
goto "loop"

:k_left
...
return

:k_right
...
return

:k_set
...
return

:timeout
print "Timeout"
end

set_zoom / set_zoom_rel / get_zoom / set_zoom_speed[]

Syntax:
set_zoom x (where x is 0 to 8, 14, or 127, see Range)
set_zoom_rel x (x is +/- relative change)
x = get_zoom (zoom-step value placed in variable x)
set_zoom_speed x (where x can be from 5-100 range. Not implemented on all cameras)
(5 is 5% of high-speed, 100 is 100% of high-speed)
set_zoom range:
Use get_zoom_steps to the number of zoom steps. Old (mostly digic 2, 3) models, except some S series mostly have between 7 and 15 steps. S-series and many newer models have 50, 100 or more.

Note 1: set_zoom_speed is not availabnle on all cameras. It is supported on S2 and S3, and most Digic 4 and later. While the speed is set on a scale of 1-100, on most cameras other than the early S series, there are only 2 - 4 speeds available. ON cameras with limited speed control, the speed changes at multiples of 25, so 0 is slowest, 75 or greate is fastest, and there may be intermediate steps at 25 and 50.

Note 2: Some cameras may not maintain focus or refocus automatically after the end of zooming. Use a click or press/release "shoot_half" command to implement a refocusing if needed.

Note 3: It was found that if using the slowest speed (5), that an S3 IS might shut down after it has waited too long for the zoom to traverse the whole range of 129 steps, a speed of 10 did not exhibit this behavior on an S3 IS. 5 is so slow though, that I doubt it would rarely be needed, except in movie-shooting scripts, and then the range could be limited to prevent camera shut-down.

Note 4: CAUTION! (found on S3 IS) If set_zoom_speed is not written into the script when set_zoom x is used, the camera will refocus some of your optics to make it where the camera is unable to focus on anything in any mode. The camera (when zooming without a set-zoom speed) appears to move an internal lens element that puts the lens into a Super-Macro mode where it focuses on internal lens elements at widest-angle. If this command is left out of a script using the set_zoom x command, you will have to shut down your camera and restart it to reset the zoom-lens' optics back to defaults. However, an interesting thing is found -- when running the "Zoom-Shoot" script by rem-ing out the set_zoom_speed command (removing it from being implemented), after the camera resets its zoom, the lens is now in a ZOOMED tele-macro SUPER-MACRO MODE! Giving you close-up focusing ability at fullest zoom! (as if you had placed a +4 or so close-up lens on your camera) Far surpassing the capabilities that Canon designed. Perhaps this "bug" could be put to great use? Or it might damage your focusing and zooming mechanisms. USE WITH CAUTION. Because you can hear the camera strain up against some internal lens-adjustment stops when it's trying to reset the zoom. And the only way to "un-do" this (really nice!) tele-super-macro mode is by turning the camera off and on again.

(Leaving this small chart here for reference, but is no longer applicable to the new set_zoom commands.)

S-Series Zoom Speed: 36mm-432mm or 432mm-36mm
slow = 6 seconds (available in single-shot & movie mode)
medium = 4 seconds (available in movie mode)
high-speed = 1 second (available in single-shot mode)

set_focus / get_focus[]

See also: set_aflock()  set_mf() get_sd_over_modes().
uBasic Syntax:
set_focus x (where x is the distance in mm)
sleep 500+? delay required after call to set_focus and before shoot/shoot_half (see below)
shoot or shoot_half required after call to set_focus (see below)
x = get_focus (the current focus distance in mm is placed in variable x)
get_focus may also be used directly in an expression where its numerical value might fit: set_focus ((3 * get_focus) / 2)
would set a new focus distance 1.5X farther than the current distance.
LUA Syntax:
set_focus(x)
x=get_focus()
Range:
x = 0 to 65535 (millimeters)
Many Canon P&S cameras will focus using just the set_focus command. If you are having problems using set_focus, try putting your camera into P mode rather than Auto. If your camera has an MF (manual focus) mode you may need to enable it (possibly by issuing the sequence of click "ButtonName" commands for your camera) for set_focus to work, or use the  set_mf() script command. Enabling AFL mode may also enable the set_focus() function. Cheaper point-and-shoots do not typically have an MF mode but may have an AFL (auto focus lock) mode - check your user manual for instructions or use the set_aflock(1) script function. Also, set_focus may not work on cameras lacking the CHDK SD (subject distance) Override Menu.
Note that most of the set_XXX commands take place during the camera shooting sequence, so they should be called before shoot or shoot_half is called, and will probably not read back what they have been set to until after shoot or shoot_half has been activated. If no set_XXX has been called prior to shoot/shoot_half, the camera will default to determining the values automatically.  
Also note that set_focus (on all cameras?) requires the execution of "shoot" before taking effect:
@title focusTest1 script
print "Focus Test1!"
for f=95 to 100
  set_focus f
  sleep 500
  rem need shoot for focus to take effect!
  shoot
  g=get_focus
  print "Set to=",f," Actual =",g
next f
end
If you comment out the "shoot" above, you will see that the focus has not changed.
Use of press/release "shoot_half" also works (focus is set correctly after the press and is retained after the release as well). And note also that the delay "sleep 500" after set_focus is required. If you remove the "sleep 500" below it will fail (Set!=B4, Set!=Aft).
@title focusTest2 script
print "Focus Test2!"
for f=95 to 100
  set_focus f
  sleep 500
  press "shoot_half"
  sleep 1000
  b=get_focus
  release "shoot_half"
  g=get_focus
  print "Set=",f," B4=",b," Aft=",g
next f
end


Furthermore, the delay required after set_focus depends upon the distance the focus motor has to travel. So a step size of 1 between focus steps might require a sleep 500, while a step size of 10 might require a sleep 1500. Also, if in your script you set_tv, set_sv, set_av, this may cause your camera to adjust focus itself in which case the focus motor travel may not be from your last focus position but instead from where the camera auto focus left it (so may require a larger delay). If in doubt, use a sleep 3000 until everything is working.
When larger focus step changes are made, the end result reported by get_focus may be +/- 1 focus step from the set_focus value. So use caution if you loop waiting for get_focus to match.

set_iso / get_iso[]

Note:
To perform the equivalent action, newer scripts may wish to use set_sv96 and get_sv96 (see below) which use the APEX standard values.
Syntax:
set_iso x (where x is one of the following values: 0 - AutoISO; 1,2,3,4,5 - 50(80),100,200,400,800; -1 - HiISO (where applicable))
x = get_iso (the ISO value placed in variable x)

set_led[]

Camera LED lamp control.

Usage:

set_led a b c

Parameter a specified the LED-lamp to act on.

The valid values for a and the LEDs that corresponds to each value are different for every camera. Typically they will be values between 0 and 15. Determining the usable values for any particular camera requires either a trial & error process of trying every value or reading the source code in the lib.c file for that camera.
The table below show some typical values for A500 series cameras.
Value of "a"  LED Lamp
 4            GREEN (by power switch on S3 and A560)
 5            YELLOW (by power switch on S3 and under green led on A560 )
 6            (not used)
 7            ORANGE (red LED on back of S3 and same place than green on A560)
 8            BLUE
 9            Focus Assist / Auto-Focus Lamp / AF Lamp (green on S3, orange on A560)
10            Timer / Tally Lamp (bright orange lamp in front on S3)

Parameter b sets the LED off or on, or a blinking LED pattern.

0 = LED is off
1 = LED is on
>1 = LED blink pattern (varies by camera?)

Parameter c (optional) controls LED brightness.

c = 0 - 200

Note : brightness only works on some early model Powershot cameras

Example Code:

rem Turn on AF_Lamp, Focus Assist Lamp
set_led 9 1

rem Turn on Blue LED with reduced brightness
set_led 8 1 35

IMPORTANT NOTES

  1. Some options of this command may not work on all cameras !
  2. When using any LED lamp controls, remember to reset them to their original condition as they were before executing your script. Failure to do so may result in your power-indicator not alerting you that your camera still powered on. Or other important camera functions involving the LED lamps may not light at their proper times.
  3. When testing the Blue LED brightness by putting it in a for x=0 to 200 loop to ramp the "c" parameter all the way up in single step increments, then and back down again, it doesn't appear to behave linearly. The LED ramps up, then turns off, briefly flashes, ramps up again, flashes, then ramps down and flashes (or something similar to that). I suspect it might be working from 0 to 127 using binary bit values. But I've not tested it for this.

get_vbatt[]

Read the battery voltage, momentary value, varies a bit.

Usage:

a = get_vbatt

Value is returned in mV, millivolts, 1/1000th of a volt.

get_vbatt acts as its own variable, allowing it to be used in calculations without first having to assign it to a variable, e.g. if (get_vbatt <= 4300) then print "DEAD BATTERY!"


set_raw[]

enable / disable RAW recording

Usage:

set_raw a

Where:

a = 0 then RAW recording is OFF
a = 1 then RAW recording is ON

get_raw[]

Returns enable / disable state of RAW recording. 1 = RAW enabled; 0 = RAW disabled

x = get_raw

As with most (all?) get_xxxx variables, the function can also be used directly in an equation or as a Boolean value:

if get_raw then [do stuff]

will execute [do stuff] if RAW is enabled.

set_raw_nr[]

Set "Dark Frame Subtraction" state (AUTO|OFF|ON).

Determines whether the camera will do a dark frame subtraction after taking a shot. Auto means the camera decides, OFF means no, ON means yes. Dark frame acquistion and subtraction typically occures for images with an exposure time of 2/3 of a second or longer. It does consume time (it's equivalent to taking another image at the same exposure time).

Note: although this command refers to "raw", it actually applies regardless of whether you are in RAW mode or not. AUTO is the state the camera normally is in. CHDK allows you to change this to the ON or OFF states, and this uBasic command allows you to change it in a script.

Usage:

set_raw_nr a

Where:

the variable a determines the state: 0=Auto 1=OFF, 2=ON

get_tick_count[]

This function returns the time in milliseconds, since the camera was turned on. 

Usage:

t = get_tick_count
get_tick_count acts as its own variable, allowing it to be used in calculations without first having to assign it to a variable.

get_day_seconds[]

This function returns the number of seconds since midnight.

Usage:

t = get_day_seconds
get_day_seconds acts as its own variable, allowing it to be used in calculations without first having to assign it to a variable.

For a simple example using this function to wait until a specific time of day before continuing, see get_day_seconds_example.

set_prop / get_prop[]

---> this section needs to be updated to reflect the actual state !

Read / Set PropertyCase Values

This is a powerful pair of commands. These are used to read and set "property-case" values in the firmware of your camera. They can be used for: detecting and setting the flash mode, mode-dial position, the internal self-timer delay, video frame rates, and more.


A new page has been created to describe the use of some of the more useful property case values. See this link The Property Case Use page


The presently known property-case values were originally taken from a list posed at a Russian authored List of known Property Cases. A more up to date list can be found here: this page of Property Case IDs [There now is a Discussion page section for user contributions to determining the values and uses of the property cases. It also has a link to script for exploring these items. You can find it here: Property case exploration.]

IMPORTANT
USE THE SET_PROP COMMAND WITH CAUTION. NOT ALL HAVE BEEN TESTED FOR POSSIBLE OUTCOMES.

Usage:

set_prop propid value
get_prop propid value


Where propid may be any of the following:

Prop_ID   Description

 0        Shooting mode dial position
 1        Photo effect
 5        White balance
 6        Drive mode (S3 values: 0=single, 1=continuous, 2=timer)
 8        Hi-speed continuous mode (S3: 1=OFF, 0=ON
 9        Metering mode (S3 values: 0=eval 1=spot 2=center)
11        Macro (S3 values: 0=normal, 1=macro, 2=super mac)
12        Manual Focus (S3 values: 1=manual, 0=auto)
14        Delay of selftimer (appears to be time in milliseconds)
16        Flash mode (s3: 2=flash closed, otherwise 0=auto, 1=ON)
18        Red eye mode (S3: 0=OFF, 1=ON)
19        Flash slow sync (S3: 0=OFF, 1=ON)
20        Flash Sync Curtain (S3: 0= first, 1 = second)
21        ISO value (S3: 0=auto, 1=ISO-HI, or actual ISO: 80,100,200,400,800)
23        Image quality (S3 values: 0,1,2 from best to worst)
24        Image resolution (S3 values: 0,1,2,4,8 for L,M1,M2,S,W)
25,26     EV correction (positive or negative, 96 units per stop)
28        Flash correction (same units as 25,26)
32        Exp bracket range (Same units as 25/26: e.g. 96 = +/- 1 stop range)
34        Focus bracket range 2=Smallest, 1=Medium, 0=largest
36        Bracket mode: 0=NONE, 1 = exposure, 2 = focus
37        Orientation sensor
39        Chosen Av (by user)
40        Chosen Tv (by user)
65        Focus distance
67        Focus ok: 1=Yes, 0=NO
68        Coming Av
69        Coming Tv
74        AE lock: 1=ON, 0=OFF
126       Video FPS (15, 30 or 60.  don't change here!)
127,128   Video resolution (S3: 2,1 for 640x480; 1,0 for 320x240)
177       intervalometer: #of shots (0 if not activated)
205       0 '1' during shooting process
206       "MyColors?" mode (See link below)
2,3,4,207,208,209,210 contain individual parameters for the "Custom" MyColors
          settting.
218       Custom timer continuous: # of shots to be taken
219       Self Timer setting: 0=2 sec, 1=10 sec, 2=custom continuous

And value may be any that is appropriate for that particular propid.

Additional information (hopefully growing) about what values might work for some of these properties can be found at the following link: Property case exploration page. This link also has a more complete description of the MyColors settings (contrast, saturation, sharpness, individual color intensities, etc)


Example script for setting and viewing Prop_IDs.

@title popcase
@param a propid
@default a 0
@param b value
@default b 0
:loop 
  wait_click 
  is_key k "left" 
    if k=1 then set_prop a b 
  is_key k "set" 
  if k=1 then goto "lend" 
  get_prop a b
  print a,b
goto "loop" 
:lend
end


Enhanced Commands[]

NOTE: Syntax usage in most cases is command_name x, where x either sets or returns the value in that command. Unless stated otherwise, assume this usage syntax. Otherwise they may be acting as their own variable, and may be used as-is in a command string. Example: get_vbatt is its own variable. It can either be assigned to another variable with x=get_vbatt, or used on its own as in print get_vbatt. The different types of uBASIC command syntax will be clarified as needed or as discovered. (Developers don't document things very well. We, as end-users, sometimes have to find these things by trial-and-error, or be perceived as a major nuisance by hounding them for any clues into what they did. :) I use both methods. :) )

Notice

For the functions listed below CHDK uses APEX96 values to set and calculate exposure.


get_av96[]

This function returns the current aperature setting in APEX96 units.

get_user_av96[]

Returns the Av setting value in APEX96 units for M (manual)  or Av (aperture priority) modes on cameras that support those modes.

get_user_av_id[]

Returns the index into the aperture table found in the camera's CHDK shooting.c file for the current Av setting in APEX96 units for M (manual)  or Av (aperture priority) modes on cameras that support those modes.

get_bv96[]

This function returns the current brightness value in APEX96 units.

get_dof[]

Get the depth of sharpness in mm, as calculated from the current zoom and aperture (Av) values. Use it as a number in an equation: n = get_dof

Arithmetic can be directly performed with the get_xxxx variables. For example, to increase the focus value already stored in f by the depth of field, write:

n = get_dof

f = f + n

Or the steps can be combined:

f = f + get_dof

get_far_limit[]

Get the maximum distance of acceptable sharpness in mm. The difference between far limit and near limit is your depth of field. CHDK calculates the values from the cameras current focal length (zoom), aperture (Av), and focus distance.

n = get_far_limit

is the most basic use, but it can be combined into more complex arithmetic expressions.

get_hyp_dist[]

Get hyperfocal distance

n = get_hyp_dist

Depth of field is that range of distances that are acceptably focused, given the lens's focal length (zoom), aperture (Av), and focus distance. Hyperfocal distance is the closest distance the lens can focus and still be sharp to infinity. When the subject distance (focus) is set to the hyperfocal distance, get_far_limit will equal infinity, and get_near_limit will be 0.5 * the focus distance.

get_sv96[]

Returns the Speed Value (ISO, image sensor sensitivity) that the camera is set to in APEX96 units. Use in conjunction with set_sv96.
The returned value is the "real" sensitivity value. You can convert to the "market" equivalent using sv96_real_to_market()
uBasic Syntax: get_sv96 x
LUA Syntax: x=get_sv96()
Note that typically get_XXX is called at the beginning of a script after a shoot_half to grab what the camera would automatically set the value to. And then get_XXX is called after a set_xxx and shoot combination later in the script along with a print or log of the value to verify that the value read back matches what was set.
If you are unfamiliar with APEX refer to the wikipedia article: http://en.wikipedia.org/wiki/APEX_system. The values used by Canon and CHDK are the APEX value multiplied by 96 (thus the 96 in the name). The simplified explanation for APEX is that the amount of light hitting the film/sensor is dependent on the aperture value and time value (shutter speed) and should be matched to the brightness value of the subject being photographed and the speed value of the film/sensor (ISO value).

get_iso_market[]

get "marketing" ISO (see ISO values for what is meant by a "Market Value".)

get_iso_real[]

get real "value" ISO (see ISO values for what is meant by a "Market Value".)

get_iso_mode[]

Obtain the CHDK ID of the current ISO mode. In general, 0 is Auto, and the following integers represent ISO values available in the Canon UI, such that 1 = minimum ISO. If the camera supports "Hi" ISO mode, the CHDK ID is -1. You can obtain the ISO value from the ISO_MODE propcase using get_prop.


get_near_limit[]

Get the closest distance that is within the range of acceptable sharpness.

n = get_near_limit

Near limit and far limit combine to define the camera's depth of field (see get_dof), the range of distances that is acceptably sharp. CHDK calculates the values based on the current settings for focal length (zoom), aperture (Av), and focus distance.


get_tv96[]

Returns the Time Value (shutter speed) of the camera in APEX96 units. Use in conjunction with set_tv96 described below.
uBasic Syntax: get_tv96 x
LUA Syntax: x=get_tv96()
Note that typically get_XXX is called at the beginning of a script after a shoot_half to grab what the camera would automatically set the value to. And then get_XXX is called after a set_xxx and shoot combination later in the script along with a print or log of the value to verify that the value read back matches what was set.
If you are unfamiliar with APEX refer to the wikipedia article: http://en.wikipedia.org/wiki/APEX_system. The values used by Canon and CHDK are the APEX value multiplied by 96 (thus the 96 in the name). The simplified explanation for APEX is that the amount of light hitting the film/sensor is dependent on the aperture value and time value (shutter speed) and should be matched to the brightness value of the subject being photographed and the speed value of the film/sensor (ISO value).

get_user_tv96[]

Returns the Tv setting value in APEX96 units for M (manual)  or Tv (shutter priority) modes on cameras that support those modes.

get_user_tv_id[]

Returns the index in the shutter speed table found in the camera's CHDK shooting.c file for the current Tv setting in APEX96 units for M (manual) or Tv (shutter priority) modes on cameras that support those modes. Note: Index 0 corresponds to 1 second, and longer shutter speeds have negative indexes.

set_av96[]

Directly sets the aperture (in apex96 units).  Rounds the passed parameter to the nearest standard Canon setting for the camera  ( e.g.  f5.94 rounds to f5.6 - values are stored in each camera’s shooting.c file). Works in any mode.
Note that most lower cost Canon point-and-shoot cameras do not have a variable aperture and simply rely upon the shutter speed, ISO setting and a Neutral Density filter to determine the amount of exposure to the subject light that is allowed to reach the image sensor. See set_tv96_direct below.

set_av96_direct[]

Directly set the aperture, without trying to round to the nearest Canon setting. Theoretically precise to 1/96 of a full f/-stop, the mechanics of the camera is unlikely to match that precision. Works in any mode.
Unlike the recommended set_tv96_direct which simply changes a timer, since this moves the aperture motor, be cautious when using this function. It may be safer to use set_av above ( it will alters the passed value to a safe setting from the shooting.c file associated with each camera's CHDK port)
Note that most lower cost Canon point-and-shoot cameras do not have a variable aperture and simply rely upon the shutter speed, ISO setting and a Neutral Density filter to determine the amount of exposure to the subject light that is allowed to reach the image sensor. See set_tv96_direct below.
set_av96_direct should allow you to use in-between values not in the table. Convert the desired aperture (f-stop) to and Av96 value with the formula:
Av96 = 192 * ln(f-stop) / ln(2)
(answer must be rounded to a whole number)
Conversely,
f-stop = 2 ^ (Av96 / 192)
CAUTION: The formulas above doesn't acknowledge any limits to the width or narrowness of your camera's aperture. Attempting to exceed the limits of your model may damage the aperture motor or mechanism.


set_iso_mode[]

Sets propcase PROPCASE_ISO_MODE either by ISO value (if the value is >= 50) or by CHDK ID, which is an ID like the one obtained by get_iso_mode (0 = Auto, -1 = High if supported, 1-n are supported ISO modes). ISO values not supported by the Canon firmware are rounded to the nearest supported value.

set_iso_real[]

Sets the sv96 override value based on an input parameter in ISO sensitivity units  (real rather than market units).

set_sv96[]

Used to set the Speed Value (ISO) with an APEX96 value. The value to be passed to the function is the "real" sensitivity value (rather than the "market" value).
The Speed Value is the sensitivity of the camera's image sensor. Typically higher sensitivity used for fast action shots at the expense of detail versus lower sensitivity used for slow/static shots with higher detail, but requiring longer exposure times.
To convert a "real" ISO value (not "market") to sv96 units, use iso to sv96( ); this is equivalent to sv96 = log2(iso/3.125)*96+0.5. Use iso real to market and iso market to real to convert ISO values between market and real values.
uBasic Syntax: set_sv96 x
LUA Syntax: set_sv96(x)
Note that you can determine the APEX96 value for ISO XXX by first setting your camera to ISO XXX then running a script which calls get_sv96 and prints the result. To set your iso: when chdk is not loaded: press set, then up to the top line then right to select the iso value, then set again. (Not sure whether the APEX96 values versus ISO values match from camera to camera, so this method will always work).
If you are unfamiliar with APEX refer to the wikipedia article: http://en.wikipedia.org/wiki/APEX_system. The values used by Canon and CHDK are the APEX value multiplied by 96 (thus the 96 in the name). The simplified explanation for APEX is that the amount of light hitting the film/sensor is dependent on the aperture value and time value (shutter speed) and should be matched to the brightness value of the subject being photographed and the speed value of the film/sensor (ISO value).
Note that most of the set_XXX commands happen when they are supposed to happen during the camera shooting process. So they should be called before shoot or shoot_half is called, and likely will not read back what you set them to until after shoot or shoot_half has been activated. If no set_XXX has been called prior to shoot/shoot_half, the camera will default to determining the values automatically.

set_tv96[]

Directly sets the shutter speed (in apex96 units). Rounds the passed parameter to the nearest standard Canon setting for the camera ( e.g.  1/105 seconds rounds to 1/100 seconds - values are stored in each cameras shooting.c file). Works in any mode but will limit the minumum and maximum shutter speed to the min and max value defined in the table.

set_tv96_direct[]

This is the recommended method of setting shutter speeds (Tv or Time Value). It uses an APEX96 value.
Note that set_tv96 (no "direct" in the name) will round Tv values to a standard camera value, while set_tv96_direct will set the exact value given. If you wish to stay within your camera's published shutter speeds (not required, but maybe you want to for other reasons) use set_tv96. For a generic list of standard values, refer to the table below - actual values are camera dependent.
uBasic Syntax: set_tv96_direct x
LUA syntax: set_tv96_direct(x)
Note that many less expensive Canon point-and-shoot cameras do not have a variable aperture and simply rely upon the ISO setting, a Neutral Density filter and the shutter speed set by this time value to determine the amount of subject light that is allowed to reach the image sensor. But don't be concerned; because of the increased sensitivity of digital image sensors (versus film), the results are still excellent after the cost reduction of removing aperture control.
If your exposures are not what you expect, try setting your camera to a fixed ISO setting (instead of auto ISO) when using set_tv96_direct. Alternatively, in your script, perform a get_sv96 at the beginning of your script after a shoot_half (which will grab the autoiso value the camera determines should be used, or the fixed setting if not autoiso), then perform a set_sv96 (with this grabbed value) coupled with set_tv96_direct before the actual shoot/shoot_half when taking shots.
If you are unfamiliar with APEX refer to the wikipedia article: http://en.wikipedia.org/wiki/APEX_system. The values used by Canon and CHDK are the APEX values multiplied by 96 (thus the 96 in the name).
Note that most of the set_XXX commands happen when they are supposed to happen during the camera shooting process, so they should be called before shoot or shoot_half is called, and likely will not read back what you set them to until after shoot or shoot_half has been activated. If no set_XXX has been called prior to shoot/shoot_half, the camera will default to determining the values automatically.
Non-standard Shutter speed tv96_direct values can be calculated with this formula:
Tv96 = -96 * ln(shutter time) / ln(2)
Answer must be rounded to nearest whole-number value.
Conversely,
shutter time = 2 ^ (Tv96 / -96)
Table of standard shutter speeds and the corresponding tv96 value (where " is shorthand for second):
speed = tv96
------------
        64.0" = -576
        50.8" = -544
        40.3" = -512
        32.0" = -480
        25.4" = -448
        20.0" = -416
        16.0" = -384
        12.7" = -352
        10.0" = -320
        8.0"  = -288
        6.3"  = -256
        5.0"  = -224
        4.0"  = -192
        3.2"  = -160
        2.5"  = -128
        2.0"  =  -96
        1.6"  =  -64
        1.3"  =  -32
        1.0"  =    0
        0.8"  =   32
        0.6"  =   64
        0.5"  =   96
        0.4"  =  128
        0.3"  =  160
        1/4"  =  192
        1/5"  =  224
        1/6"  =  256
        1/8"  =  288
        1/10" =  320
        1/13" =  352
        1/15" =  384
        1/20" =  416
        1/25" =  448
        1/30" =  480
        1/40" =  512
        1/50" =  544
        1/60" =  576
        1/80" =  608
        1/100" = 640
        1/125" = 672
        1/160" = 704
        1/200" = 736
        1/250" = 768
        1/320" = 800
        1/400" = 832
        1/500" = 864
        1/640" = 896
        1/800" = 928
        1/1000" = 960
        1/1250" = 992
        1/1600" = 1024
        1/2000" = 1056

set_user_av96[]

Sets the aperture to be used (in APEX96 units) on cameras with M (manual) or Av (aperture priority) modes when those modes are selected.  Overrides the values set by the Canon UI.

set_user_av_by_id_rel[]

Like set_user_av96 (above) except that the aperture setting used is taken from the aperture table for the camera in the CHDK shooting.c file.   The actual value used from the table is determined by the index value passed as a parameter to the function.

set_user_av_by_id[]

Like set_user_av96 (above) except that the aperture setting used is taken from the aperture table for the camera in the CHDK shooting.c file. The actual value used from the table is the current value in the table the offset by the index value passed as a parameter to the function.

set_av[]

deprecated - use"set_user_av_by_id

set_av_rel[]

deprecated - use "set_user_av_by_id_rel"

set_user_tv96[]

Sets the shutter speed to be used (in APEX96 units) on cameras with M (manual) or Tv (shutter priority) modes when those modes are selected. Overrides the values set by the Canon UI.

set_user_tv_rel_by_id[]

Like set_user_tv96 (above) except that the shutter speed setting used is taken from the shutter speed table for the camera in the CHDK shooting.c file.   The actual value used from the table is determined by the index value passed as a parameter to the function.

set_user_tv_by_id[]

Like set_user_tv96 (above) except that the shutter speed setting used is taken from the shutter speed table for the camera in the CHDK shooting.c file (comment: might be an idea to link to this table - SkepticaLee). The actual value used from the table is the current value in the table the offset by the index value passed as a parameter to the function.

set_tv[]

deprecated - use "set_user_tv_by_id"

set_tv_rel[]

deprecated - use "set_user_tv_rel_by_id"

Example Exposure Setting Script[]

If you are using this to set a shutter speed, set it to 138*ln(x), where x is the time in seconds.
Example of usage (set_shutter for Ixus) by Allbest
@title Shutter Test
sleep 500
rem initiation
press "shoot_half"
release "shoot_half"
get_tv96 t
:set_shutter
        print "Tv set to",t
        wait_click
        is_key k "set"
        if k=1 then goto "k_set"
        is_key k "down"
        if k=1 then t=t-32
        k=0
        is_key k "up"
        if k=1 then t=t+32
        k=0
        set_tv96_direct t
        goto "set_shutter"
        :k_set
        shoot
        end

wheel_right[]

Simulates the movement of the jog dial one click clockwise.

wheel_left[]

Simulates the movement of the jog dial one click counter clockwise.

get_autostart[]

Parameter checking autostart for scripts.
Syntax: x=get_autostart (or used as its own variable string in calculations, see get_vbatt example)

set_autostart[]

Set this option to autostart scripts.
Be careful with these commands. Autostart opens the script when the camera is turned on.

get_usb_power[]

Checks for USB connectivity. Works for A and S series.
Syntax: x=get_usb_power

shut_down[]

Simply powers-down the camera. Useful for Remote USB scripts where the USB signal may wake up the camera, execute some script function, and then shut down the camera again when done, to save on power for lengthy remote-shooting needs.
Example, if x=(some calculation) then shut_down, or just used as a line on its own at the end of your script.
Note: in Lua, post_levent_to_ui('PressPowerButton') can also be used, which may prove to be more reliable as it will be treated by the camera firmware just like a real power button press.

get_disk_size[]

get_free_disk_space[]

Returns values in KB. Scripts can now be stopped when specific disk limit exceeded. For easier calculation divide by 1024 to return the value in MB.
Syntax: x=get_disk_size, x=get_free_disk_space
Example, to print the space left in megabytes, print get_free_disk_space/1024 (this command acts as its own variable)


get_jpg_count[]

get_raw_count[]

Syntax:
x=get_jpg_count,
x=get_raw_count
Returns the calculated value of how many JPG or RAW shot space is left available on the SD card. JPG value is approximated and taken from an average of file sizes using Canon's own algorithm, in the same way that shots remaining in the EVF/LCD display are calculated. This command can be used to detect when not enough space is remaining for script, and e.g. either end the script or shut down the camera.
Note : Deleting image files with a script will not cause this value to change as it only updates once after each shot is taken. Also, the function may return zero until the first shot is taken after the camera is powered up.

set_nd_filter[]

Controls the ND (Neutral Density) filter

Parameter:

0 = OFF
1 = ND filter IN
2 = ND filter OUT

This ability replaces aperture override menu entry for most Ixus series cameras and also some of the cheaper Axx cameras.

get_raw_nr[]

Returns the condition of your NR (noise reduction setting).
Syntax: x=get_raw_nr

USB Remote Cable-Release Function[]

This amazing feature was found by a talented Ukrainian programmer known as Zosim. You may find his original source code and executable binaries for the A710 IS camera at CHDK binaries and source and photos to build simple cable-release switch.

Current documentation on this feature can be found here :  USB Remote  with details about scripting here  USB_Remote Scripting_Interface



Between MX3's Motion-Detection options and this amazing USB cable-release method, there is no limit to the various ways you may control your camera by remote means. Any simple electronic circuit that can close a switch and feed a 3v to 5v DC signal to the USB port's proper contacts (observe proper polarity!) can now be used. There is also no limit to the length of wire that you may use, as long as you keep the final contact voltage at the camera-end between the 3vdc and 5vdc range. Use sound-sensitive circuits to record when sound-events happen. Use light or motion changing events to trigger shooting sessions. Use any CHDK intervalometer scripts or electronic intervalometer circuits to trigger shots. (There are thousands of simple circuits like these all over the internet.) Have your mouse or cat press a switch to record their vanity-quotient for a science-fair project! The sky (literally) is the limit to how many ways you may use these functions.

Have fun!


Debugging: uBasic[]

Understanding the Unk Alert, uBasic only

This tiny version of uBASIC includes some debugging help. When running a script with a bad command you might sometimes get a uBASIC:nn err statement printed in red in the top-left corner of your EVF or LCD display. This will alert you to why your coding didn't work, albeit in a very abbreviated format giving the line (nn) and error message.
Some exmaples of what you might see, and what they will mean:
uBASIC:24 Unk label Line 24 Unknown label 
uBASIC:32 Parse err Line 32 Parse error - syntax error in uBASIC command
See the following sections for IDE and debugging aids ideal for both novice uBASIC developers as well as the more experienced.


Some unexpected behaviour of uBASIC[]

These are my observations, which might be inaccurate.

do not "execute" labels[]

After release #68 this is not true, you can leave out the "goto "nega"" statement. Also the extra space after the label is not necessary any more.
if a<0 then goto "nega"
let a=5*6
goto "nega"      
rem If this line is left out and a>=0 then an error 
rem (unk statement or unk label) will be generated
:nega


Debugging Scripts on a PC or Mac[]

There are now two ways you can test your CHDK scripts without needing to load them into the camera every time, finding the error and then changing a line, loading it into the camera again and again. The first way is to use the ubasic_test program, a simple batch program which only runs under Windows. The second way is to use the UBDebug program which runs under Windows or Mac OSX.

Using UBDebug - an Integrated Development Environment for Scripts[]

There's now an interactive development environment for uBasic scripts. Written in java with native support5 for both Windows and Mac OSX it lets you load a script and step through it line by line, inspecting and setting variables. You can also set the values to be returned by functions (such as get_usb_power) and alter the value of properties. A simple breakpoint mechanism is available. Scripts can be edited and saved to disk. For details see here

Using the UBASIC_TEST.EXE Console[]

Download this small file http://web.archive.org/web/20070806121635/http://grandag.nm.ru/hdk/ubasic_test.rar (BEWARE - LINK TRIES TO INSTALL ADWARE ON YOUR COMPUTER!  SUGGEST FINDING THE FILE ELSEWHERE).  UnRAR (like UnZIP) it to your scripts working location on your hard-drive. You should have a file named ubasic_test.exe in your scripts-work folder now. You have to run this program from a Windows Command Prompt (the old time DOS window). Some people have a "Launch Command Prompt Here" on the right-click menu of Windows Explorer, so you can just right-click on the folder where your scripts and ubasic_test.exe file reside. (You can get this by installing "Open Command Window Here" Power Toy, available here.) Or you can go to Programs > Accessories > Command Prompt (where I have mine for some reason). And use the CD command to Change Directories until you get to where your scripts and ubasic_test.exe file reside. For example, if you start out in root directory C:\ and your scripts are on drive D: in a sub-folder called CHDK\Files\Scripts\, at the command prompt just type
cd D:\CHDK\Files\Scripts
and you'll be where you're supposed to be. (You might want to rename that little program to just test.exe to make it easier to type each time.)
To test one of your scripts in that folder, at the Command Prompt, just type "ubasic_test scriptname.bas" (without the quotes). Where "scriptname.bas" is the name of the script you want to test. It will use the default settings you have assigned to your variables. For testing you should change some of those values to make sure everything is working properly under new user-defined settings. (The reason I suggest you rename that ubasic_test.exe to just text.exe, is then all you have to type is "test scriptname.bas", saving you a few key-presses.)
The easiest way to run console programs is to use a file manager which has a command line. For example, Far Manager or Total Commander.
You can also test your scripts via drag&drop with a batch file. Here's how to do it:
Open a texteditor and put the following lines in there:
@ubasic_test.exe %1
@pause
Save this as "ubasic_test.bat" in the same folder where your ubasic_test.exe is. Now you can drag a script with your mouse onto this batch file and it will be executed. (This would also work without making a special batch file, but we need the "pause" command to read the output).


You may need to modify your BAT file to have the @ubasic_test.exe %1 line to include the full path to your ubasic_text.exe file, as well as enclosing the variable %1 in quotes, in case your script's filename includes any spaces. For example:
@H:\Tests\CHDK_Files\SCRIPTS\ubasic_test.exe "%1"
@pause
If you run into problems and this still doesn't work (using this drag & drop method):
  • 1) Make sure your ubasic_test.exe file and scripts are not in any path that contains spaces. (Example: you can't have it in a sub-folder path of "D:\CHDK Files\Script Tests\ubasic_test.exe" Change those spaces to _ (underscores) in your actual folder-names if need be.)
  • 2) Your BAT file association may have become corrupted. Here's a handy page of Windows® XP File Association Fixes Get the one for Batch Files. (Save them all, they may come in handy one day!)
(How did I find this out? I had all these problems going for me. :-) )

An alternative drag and drop method (WinXP):-

1) Rightclick on uBasic.exe and make a shortcut on desktop,
 2) Find/search for your script.
 3) drag your script to uBasic icon letgo and it runs!

You may have to adjust the 'Icon' properties to keep the result on-screen

The addition of a few extra print and rem statements will help debugging, also include values to replace the @defaults.


References[]


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