Project Horus High altitude balloon project


External triggers code

I had a chance to rig up the external trigger on the main camera (the Lumix) this weekend - it didn't go as smoothly as I'd hoped. This camera pretty much kicked my butt - it's usually a good idea to safely discharge the flash capacitor before working inside a camera. Usually you'd do this with a resistor - alternatively, you could forget to do so and accidentally shock yourself half a dozen times. Eventually I de-soldered the capacitor to save myself further pain.

This camera (not surprisingly) was much more intricate and complex than the toy that is the Kodak - it was a bit of work just to reach the shutter button contacts. After eventually getting the right bits off, I decided to test the camera & ensure I was dealing with the right contacts - this went fine, until I touched part of the (metal) casing against the circuit board & smelt smoke.

Much cursing later, I realized I'd blown a fuse - trouble was the size of the fuse - only 1mm or so! I don't have any tiny SMD fuses, much less the skill or tools to solder them, so I bridged the 2 end of the fuse with a drop of solder, which solved the problem.

I eventually got the shutter connected to an external trigger (though this also proved tricky) and put everything back together. There are 4 pins on this trigger - 2 for focus and 2 to release the shutter - though it seems operation on only 2 pins (focus + shutter) is possible.

I've also written more code for the GPS side of things - all the useful data is parsed out of the NMEA sentences, checksums are validated, etc.

Also realized my temperature sensors are only good to -40 degrees C, significantly warmer than the payload will be exposed to. I've ordered 2 DS18B20 sensors capable of reaching -55 degrees to replace them.

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  1. Sounds good, and looks good.
    Im looking forward to seeing what it amounts to.
    Hopefully once its done you get slashdotted at the minimum :)

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