[sdiy] Retaining button state after power off?

[Tom Wiltshire]

I agree with Roman. The 12F EEPROM has an expected life of 1,000,000 writes, so if you write the current setting to the EEPROM every time you press one of the buttons, most cheap buttons will fail before the EEPROM does. Of course, if you put expensive MEC buttons on it (10,000,000 operations expected life) then you probably will have to replace the uP at some point, if the rest of it hasn't died by then. It's an odd world we live in when a whole computer on a DIP costs less and takes up less space than a couple of flip-flops, but that's how it is.

Personally, I don't like the CMOS+batteries idea, but then I've seen the inside of too many Polysixes. Ugh. Who'd want to add that feature to their design?!

T.


On 1 Feb 2014, at 16:26, Roman Sowa <modular at go2.pl> wrote:

> With typical PIC12F family EEPROM endurance and ridiculous 20 daily reboots of the device you still have way more than 100 years before having to worry about endurance. And by that time the circuit will be long dead because of dried capacitors, solder whiskers, dust, humidity, worn out pots and switches, and electrostatic discharge.