Ok, if everything is battery-powered, you're good. However, as soon as mains power is involved anywhere, galvanic isolation is a must just in case there's some sort of short circuit. I was lucky (or prudent, don't know which) enough so far to avoid any encounters with mains voltage, however, as the firmware guy, I don't do quite as much poking around the internals of, say, power supplies as the hardware guys do.
The other one takes those and handles the SPI for writing to a memory card.
Hm, an interesting dual-processor setup. Does it have any advantages power-wise compared to, say, using one of Atmels ARM chips? That's what I am working with right now. If you're planning to have the device running on batteries for a week, you're probably looking at an ever more limited power budget than I am.
I'd be *very* interested in hearing more about your design: anything online?
Since this is part of my job, I'm afraid I can't spill any corporate secrets.
Computers now do what they are programmed to do when the user uses the specified input device in a specified way!
And I guess you didn't read my post.
It doesn't matter when google decides to refresh it's cache. You can still get an invalid entry, an entry they haven't cached, or an entry that is currently being refreshed.
Any DNS server can choose how frequently to refresh it's cache, whether it updates or purges during a refresh, and whether or not to return the stale result (be it stale according to the official TTL or stale according to your own refresh frequency) while refreshing.
Updating your cache 1 hour before it needs to be updated is not magic. They just use a higher standard for the expiration date, and pay a price for it.
Without life, Biology itself would be impossible.