Time lapse controller
I've been playing with time lapses, mostly using my Canon SX210 running CHDK. While the results have been OK, my Sony NEX takes much better pictures, so it seems a shame not to be able to use it. I found an intervalometer for my phone (the NEX uses an IR remote shutter release), and that allowed me to shoot stuff like this, but I'd like to be able to use it elsewhere.
I've seen stuff like this, and it's got me to thinking.
The LapsePi setup is geared towards a Nikon camera, which uses a wired remote. I have a Sony, which uses an IR remote. Doh.
I picked up a cheap generic Sony IR remote for a few dollars, and it works. Yay. I took it apart, and it's a fairly simple little circuit board inside, with a blob button that just makes the connection for the battery.
Oh, and it's running a 3.3V CR2025 battery, which is very helpful.
I tried just dropping a blob of solder on the circuit board, but it'd never stick, so I tracked down either side of the "switch", and soldered a wire across it. Testing with the battery proves that as soon as power is applied, the LED lights up. Well, I say "lights up" - it's infra-red, so I can't see it - I have to point a camera at it while I'm testing, to prove that it works :o)
I had an old VGA header from a graphics card that I've since replaced, and it has fewer pins than a full GPIO cable, but it'll fit through the SD card slot in the case I'm using - which is close to the GPIO extender port that'd there now that the screen is using the header on the motherboard. I plugged this in, and did some ganky wiring to test it out. It didn't work. I then figured out that when people say "GPIO 17", they actually mean pin 11, obviously...
I got that all sorted out, and it looked like the Pi was controlling the LED correctly. A test with the Sony proved that it was :o) I'm aiming to take the LED off that little circuit board, and put it on a couple of longer wires so I can point it at the camera. For now though, I need to tidy everything up, and start thinking about the motor.
I took the little circuit board apart - basically I took off LED and soldered that to a couple of wires, so I can put it where it needs to be while the circuit board stays put. I also took off the battery connectors, and soldered those to a little 3 pin connector to the Pi. When I tested it, it all didn't work, and I discovered that I'd screwed up the polarity of the LED. As I'd heat-shrinked the LED end, I just swapped the wires on the board, that's why "-" is red. You can't get the staff, can you?
The second test showed that everything is now working.
I built a base out of an old piece of aluminium I had lying around, then bolted on a speaker mount - it's the same thread as a tripod mount, and it's designed to hold a lot more weight than my camera. I've attached a little levelling bubble, and the RPi mounts with some velcro.
I had to build up some runners...
The plan was to drill 3 holes at each end of the runners - one vertically to mount it to the base, then 2 holes diagonally to mount the skateboard wheel bearings I'm using as wheels. I ended up using 1/4" screws, and using nuts to space the bearings out far enough to sit on the rail nicely.
The rail is currently just 1/2" plastic tubing, but that'll probably change as I don't think it'll be strong enough over any sort of length.
Now I just need to figure out the drive system.