[sdiy] Retaining button state after power off?

[Roman Sowa]

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.

But also I like the idea of putting small battery. The state of the 
selector will be done using some CMOS logic register anyway, so why not 
just put some diodes and lithium battery to backup power just for that 
chip. In 20-30 years, when there's time to replace battery, someone will 
have to service the module anyway.

Roman

W dniu 2014-02-01 08:34, Ullrich Peter pisze:
> Yes, an ATTiny35, 45 oder even 12 or 13 could do the job also quite nice, but you have to take care of the maximum write endurance... If you have lots of writes then the FRAM based MSP430 types could help... Nearly unlimited writes possible there...
>
>
> Ciao
> Peter
>
> http://www.ullrich.at.tt
> ________________________________________
> Von: synth-diy-bounces at dropmix.xs4all.nl [synth-diy-bounces at dropmix.xs4all.nl]" im Auftrag von "Paul Anderson [wackyvorlon at me.com]
> Gesendet: Samstag, 01. Februar 2014 04:33
> An: Justin Owen
> Cc: SDIY List
> Betreff: Re: [sdiy] Retaining button state after power off?
>
> Just drop an attiny45 in. They're small and cheap.
>
> Sent from my iPhone
>
>> On Jan 31, 2014, at 11:51 AM, Justin Owen <juzowen at gmail.com> wrote:
>>
>> Hello,
>>
>> I have a couple of simple analog circuits that allow you to cycle through 2, 3 or 4 options/outputs/etc using a momentary push switch.
>>
>> So, for a 2-cycle switch, click 1 is 1, click 2 is 2, click 3 returns back to 1 and so on. For a 4-cycle it's 1,2,3,4,1,2,3,etc.
>>
>> The circuits output either a high or low state
>>
>> The problem is that these circuits return to their default state on power off.
>>
>> What would be the simplest way to write the button state to some sort of non-volatile storage that could be reinstated at start-up?
>>
>> I'm guessing a micro is going to be the most likely answer - but if there is a non-programming option available it would be great to hear. Failing that - absolute simplest solutions where possible please!
>>
>> Thanks,
>>
>> - J
>>
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