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Attiny85 the right choice for 24h led timer? (lemmy.world)

submitted 1 year ago by [email protected] to c/[email protected]

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My wife gifted me this super cute mini miffy diorama from a gachapon. It uses two 1,5V cells and has a tiny led in it. I would really love to to add a 24h timer. ( it should stay on for 4 hours after turning it on then go to "standby" for 20h before turning back on) Do you guys think an attiny85 is the right thing for the job? Sorry of the question is dumb in any way. I am absolutely not an electronics guy.

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[–] [email protected] 2 points 1 year ago (1 children)

If it doesn't matter if it's a few seconds too late or too soon an ATtiny 85 is good. If you need more accuracy you probably need an additional RTC.

[–] [email protected] 4 points 1 year ago

You could also use a crystal for the ATtiny and get the same accuracy as the RTC. It should be accurate to about 20-30 seconds per month with a good crystal.

The internal oscillator only has an accuracy of around 1% after you calibrate it. It would be off by over 7 hours after a month. It's also quite sensitive to voltage and temperature changes.