Arduino data logger with WDT/RTC

Forum 2005-2010 (read only) Hardware Interfacing
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Hi,
I'm trying to build a single channel data logger which will be battery powered so needs to be low powered.

My idea was to read the AtoD and write the value to a SD card every second for 24 hours. Between reads I hoped to put the Arduino Duemilanove to sleep.

I can put the Arduino to sleep OK but what is the best way to wake it every second to take a measurement? I think there are two options, either the WDT or an RTC.

If I use the WDT are there any problems with the bootloader? A code example would be appreciated.

If I use an RTC (this will be a first for me) how do I control it, by SPI? (I have a DS1305) A code example would be appreciated.

Thanks

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Adafruit Data logging shield for Arduino [v1.0] : ID 243 : $24.80 : Adafruit Industries, Unique & fun DIY electronics and kits is a great shield for datalogging. On the documentation pages there is a RTC-lib which works great

http://www.ladyada.net/make/logshield/rtc.html

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Another option is the datalogging shield from nuelectronics. They are in the UK, but the size of the shield makes posting it anywhere not an issue. Cost before postage at 1 Nov 10: abt US$17

Has RTC and interface for SD card, and the analog inputs are all available. (Shield gives you nice connector options, too.) I don't know about the "sleep" part of your needs... but doubt there's anything about the shield to get in the way.

See Nuelectronics Data Logger Shield for Arduino - ar3nd

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tkbyd

Thanks for info, the nuelectronics board is very appealing as I live in the UK.

Thanks to all for your help.