Its been a while since I last upgraded the (not so) Quick Weatherproof Camera Box, but in light of the spectacular sunsets and long days here in Scotland, I revisited the "dump it and retrieve it later" aspect of the box.
Up till now I have been content to dump the box, and retrieve it a short while later, but I started thinking about the problem of getting the camera to sleep for long periods and wake up at a particular time, day, month, year perhaps.
The alarm clock idea works, but you are limited to one wakeup per day, not ideal for timelapses, or sunsets which inconveniently take place at a different time every day, so with this in mind I thought I'd throw a micro-controller in to the mix.
The design goals were..
1) Easy to replicate, so it has to use easy to find parts.
2) Relatively inexpensive (if it bites the dust due to environmental problems, or someone nicks it, I don't want to have to explain the problem to my bank manager).
3) It must be low power (actually this is probably he most important aspect of the design, it should be possible to run it for weeks or even months in sleep mode).
4) It must be flexible, easily re-purposed for time lapses or sunsets or whatever other daft use I think of for it..
What I have so far is entirely made from "jelly bean" parts, and the BOM comes to under £10.
It consists of an Arduino Pro Mini clone, a nokia 5110 display, the 8205 dual mosfet, rtc module and a salvaged lipo from a laptop battery pack (any 18650 lipo would do, I just happen to have a stack of laptop salvaged ones).
I'll post some images and a quick video of it all on the breadboard shortly.
The low cost of it all is in part, down to taking a punt on the cheapest Chinese supplier of each component. So far none of them have let me down.
Coding so far allows me to work out sunrise and sunset times to within a few minutes based on my location (lat/long), and the date/time from the RTC. I am running everything completely out of spec. The whole show runs from the lipo, so my atmel is running at 16MHz on 3.3V, the "5V" nokia 5110 LCD likewise.
Everything seems to run perfectly well despite this, and I can get the standby power down to <250uA without much effort and no real optimization, theoretically it will go to 1uA...
