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Jul 28, 2017, 11:30 AM
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Intervalometer test 1


It took a whole commute just to install the board & fix the firmware enough to make it work. It's a very high density board built around the size of the ATMega. There wasn't enough room for a button, so the only way to set the timing is soldering on a 5 pin programming header & flashing it. There are pads for a serial port, so it could be configured by a VT100 interface. It's started by shorting a jumper. Losing the jumper would be fatal.


Of course, any bluetooth module would be the same size & have a wireless interface, but there wasn't enough time to build up the software.


This revealed the Samsung takes .5A when idle & spikes over 1A when shooting a still photo. For video, the current was a constant .8A. When shooting photos at full speed indoors, the heat reached 55C or 131F.


It immediately became clear that the Samsung loses its settings without power. The mane setting is a timer which defaults to 2 seconds. Retaining the settings would require always having a battery in, so terminating the offboard battery connector.

The decision was made to shoot photos as fast as possible. The mane limitation is compression speed rather than SD card speed. UHS 1 or UHS 3 cards only got only 1 photo every 1-2 seconds. It buffers 3 frames while writing.


The debouncing on the shutter button is very forgiving compared to Goog's non deterministic, fuzzy debouncing algorithms. You can make the intervalometer fire as fast as possible while it's still writing to the card & it'll shoot again whenever it's ready. Tested it up to 8 Hz & backed it off to 4Hz to guarantee it would work. At this speed, the display shows "capturing" most of the time instead of the remaneing storage. At 4Hz, it's like a little kid banging on the shutter button, so it remanes to be seen if it crashes.



It took a bit of heroic soldering to bring out the shutter signal. All the components are 0201. Cut open as much material as possible from the battery orifice to allow easy access to the mane board & get a little more air circulation. There was plenty of room to have wires on top of the mane board.
Last edited by Jack Crossfire; Jul 28, 2017 at 08:22 PM.
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