So I have just got a SX230 HS. First thing I did out of the box was install CHDK
I built the normal USB Remote with a 3V battery, switch and connector. I found it to be quite annoying and almost unusable as I am used to using a very old Bridge DSLR (3MP Fuji) with a 2-stage button remote; so I decided I would make an adapter.CHDKremote2
is a two stage remote control adapter for CHDK.
My design uses 2 CR2032 batteries, a 5V Low Dropout Regulator (I used a LE50CZ), a Microchip PIC10F200 and a cheap 2-stage standard camera remote (from eBay). The PIC is programmed to work with CHDKs normal remote mode (not synchable mode). A spare input only pin is present on the PIC (I am working on IR remote support using this spare pin and a TSOP4838 IR reciever)
In the spirit of CHDK the PIC source code/firmware is under the GPLv2, and the circuit board/design files are under the TAPR Open Hardware Licence.
On the left is the 2-stage remote, in the middle is the USB connector for the camera and on the right is a small enclosure with the batteries, LDO, PIC and the power switch just visible on the top right of the enclosure.
The insides of the small enclosure, showing PIC, LDO, Batteries and Switch. All of the wires have now been hotglued down to prevent damage during use.
The back of the (home-etched) PCB and my bad soldering.
If you want to make one of these, you will need some way of making a PCB (I used toner transfer, although any method should work as the board is very simple), and a way of programming the PIC with the firmware (PICkit 2/3, simple JDM programmers etc all should work, or if you really can't program the PIC - message me, but you will have to pay for the PIC and postage to you (I am in the UK)).
Don't forget to take a look at "CircuitBoardDesign.png" which shows the orientation of all the components, and has the external connections labeled ("mode" is unused in the current firmware).
1x PIC10F200 in DIL-8 package http://www.rapidonline.com/Electronic-Components/Pic10f200-i-pg-Microcontroller-73-1952
1x 8pin DIL IC Socket http://www.rapidonline.com/Cables-Connectors/8-Pin-0-3in-Turned-Pin-Socket-22-1720
1x LE50CZ or equivalent 5V LDO http://www.rapidonline.com/Electronic-Components/Le50cz-Ldo-Reg-5v-0-1a-2-st-82-3012
1x PCB mount switch http://www.rapidonline.com/Electronic-Components/Spdt-Miniature-Slide-Switch-4-4mm-ACT-6-Volt-78-3762
1x Dual CR2032 coin cell holder http://www.rapidonline.com/Electrical-Power/20mm-Dual-Coin-Cell-Holder-18-3625
2x CR2032 batteries
A USB Mini-B connector & cable (chop a normal MiniUSB cable in half, Red to "USB-Out", Black to "USB-GND", DO NOT connect the white, green or shielding to anything)
Some Copper-Clad PCB
A 2-stage button camera remote (bought off of eBay)
A small enclosure - I used http://www.rapidonline.com/Tools-Equipment/ABS-Box-56-X-31-X-24mm-Black-30-1912
Download (source, designs, HEX for PIC): http://dl.dropbox.com/u/39043879/CHDKremote2.zip