atmel chip with real time clock

hi,
i posted here because i though might more response, anyway im learning c at the moment and would like to build a board with atmel chip which has an internal rtc in it ive tryed to search the atmel site but got lost could someone please point me in the right direction please
thank you

You want to build a minimal board with Atmega328P-PU and an RTC chip? Maxim makes several RTC chips with I2C or SPI interfaces, with internal oscillator or requiring external oscillator, and thru hole packages or SMD. DS1307 is common, needing external crystal, has I2C interface, thru hole & SMD available. Other SMD only parts are DS3231 and DS3234, with internal oscillator, and I2C and SPI interface (not sure which is which). www.maxim-ic.com

hi im wanting to build a bare bones board with a inboard rtc i stumbled upon this one ATMEL ATMEGA8-16AU, on ebay am i correct in saying it has a rtc in the data sheet it calls it an internal oscilator is this the same as a rtc? or if you could recommend a popular atmel ic with rtc would be great thanks

http://www.taydaelectronics.com/datasheets/A-073.pdf

Please don’t cross post. We don’t want numerous threads about the same question.

The chips do have an internal oscillator - and you can write a sketch that will keep track of time, mimicking the function of an RTC. If you don’t keep it powered all the time, you will lose the time tho. RTC chips have the advantage of really low power draw allowing them to maintain time keeping for years on a coin cell battery.

ok 3rd time lucky :)

im looking to build a barebones board atmel with an internal clock i found this one on ebay ATMEGA8-16AU really good price as well 1.99usd, my question is this in the data sheet it says there is an Internal Calibrated RC Oscillator, is this a rtc

if im correct in thinking its a rtc would this be easy to program using a usb/ttl programmer? thank you

http://www.atmel.com/images/atmel-2486-8-bit-avr-microcontroller-atmega8_l_summary.pdf

ok 3rd time lucky

Well I gave you a full answer and then the thread has disappeared when I posted it and it was lost.

the data sheet it says there is an Internal Calibrated RC Oscillator, is this a rtc

No.

A RTC is an oscillator and counting registers and also has a way of running when the main power is removed.

thank mike yes i realise this obviously i intend on having a battery on my barebones board, ive tryed to do a search on atmel but it keeps on locking up anyway im learning c thought it would be fun to build a board with an internal rtc is there a low end ic that has an internal rtc, ive searched atmels procusta but tbh there are so many i get lost, maby someone could recommend me an ic? thank you

Please stop asking the same question in multiple places.

And no, there are Arduino compatible microprocessors with an internal RTC. You can write a sketch for the uC to act as an RTC, it is not hard to do.

Quite true. The only Atmel product I know of that has an internal RTC are some of the Xmega's which are not Arduino supported.

Note, you will probably still want an external 32.768kHz Oscillator for any of these, since the accuracy of the internal oscillators is questionable on longer time scales.

I'm sure that you could program the Yún to get the time from the web.

That would hardly be barebones tho ;)