Hi, i'm using the time library on the arduino page: Arduino Playground - HomePage , it worked perfectly for my arduino uno. but when i decided to make a standalone version of my project with the ATtiny85, it has been having offset issues. I think it it 15 mins late everyday, so my clock isn't functioning as it should. I'm using the attiny85 with this core: Google Code Archive - Long-term storage for Google Code Project Hosting. wiht the 1MHz internal osciallator bootloader. I'm thinking the different clock speed might be causing this, but i do not know how to fix it.
Thanks
15/(24*60)*100 = 1.04% That's what Atmel guarantees after the internal oscillator has been tuned. In my experience, if the voltage and temperature are fairly stable, it can be tuned to about 0.2% (which is about 3 minutes per day).
If you want better than 3 minutes per day you will have to use an external crystal or a real-time clock (RTC). Or, you could try getting lucky by tuning the internal oscillator.
oh, alright, makes sense, i guess ill have to use some sort of external oscillator.