CHDK allows you to automate your camera by running "scripts", small and simple programs written by end-users and executed on the camera. Currently, CHDK allows you to use scripts written in Lua (filetype: *.lua) and uBASIC (filetype: *.bas). The file extension indicates how the script should be parsed. There are scripts for exposure bracketing, focus bracketing, intervalometer and many more.
Running a script
- Download or write your own script and place it in the chdk/scripts/ folder of your SD-card with the proper extension (.lua for Lua scripts, .bas for UBASIC scripts).
- Enter the script menu, load the script, adjust the parameters to your liking and leave the menu.
- While still in <ALT> mode just press the button and the script will start. A mini console will be displayed while you run the script.
- Note: set the Review parameter in the NORMAL camera menu to "off", other options like "x sec" or "hold" will interfere with the execution of scripts.
- You may interrupt a running script by just pressing the button again. Or pause a running script by exiting <ALT> mode, if paused the script will resume right where it left off when re-entering <ALT> mode.
Running a Lua script
- The script should be saved with the filename extension .lua in the CHDK scripts folder chdk/scripts
- Lua scripts support libraries, place these files in either chdk/scripts or chdk/lualib (see Lua syntax: Libraries).
Running a uBASIC script
- The script should be saved with the filename extension .bas in the CHDK scripts folder chdk/scripts
Differences between Lua and UBASIC
uBASIC was the first scripting language supported in CHDK and is a smaller language (both in memory size and extensiveness of features). Lua came later and can be found in CHDK builds > version 0.5 / changeset 512. In general Lua scripts will use more memory and run faster. Some scripts use particular implementation details of one or the other language and will need some re-factoring (re-writing the flow and content of the program) in order to accomplish the same goals
- CHDK Scripting Cross Reference Page
- Script commands - New uBASIC and Lua scripting commands
- The script board on the [CHDK forums]
- Lua - An introduction to Lua on CHDK
- Lua Reference - Describes additional and/or changed scripting commands for the Lua scripting language
- Lua Syntax - Basic syntax for Lua scripts
- The Lua script board
- uBASIC Syntax
- Scripting Tutorial, including a description of available uBasic script commands.
- uBASIC Syntax Highlighting for BBEdit
Setting up a development environment
For help in setting up a Lua development environment, see Lua Development Environment. Scripts can be tested locally and then uploaded to the camera. You may wish to build CHDK without some components to increase the available memory on the camera.