Data logging chips: EEPROM and RTC recommendations?

dwegscheid

Putting together a data logger: need a fair about of memory (probably 32-64 kbytes). I think I might actually know what I doing (ha!), but want to see if anyone's experience can keep me out of trouble.

I see lots of articles and recommendations for 24LC32 or 24LC65. Will using a 24LC256 be as straightforward?

My preferred vendor (Jameco) does not show the LC parts in the catalog. Near as I can tell from the datasheet, the differences between the 24C and 24LC parts is tolerence to power supply and temperature diffs (LC seems more robust). I'm in a room temp environment with a good regulated 5V supply. I should be able to use the 24C* parts, yes?

For the RTC, I've seen postings extolling the DS1302 and the PWB. Since I'm already using an I2C EEPROM, using the DS1302 makes sense. Can I bus the chips together and save IO pins?

RTC: what have people's experiences been with backup? Supercap? Lithium? I've seen conflicting information on the trickle charge feature of the DS1302; one app note said only use it for supercaps, a quick glance at the dallas data sheet seems to indicate it's usable for Lithium also.

tia...

Forrest

The 24LC256 is simple to use. If you search thru the Nuts & Volts Stamp columns available on www.parallax.com you'll find there are PBasic Stamp programs that use smaller 24LCxxx chips - you'll just need to adjust the address range for the 24LC256. Note the DS1302 has a regular serial interface, while the DS1307 has an I2C interface.

dwegscheid

I suspected that the examples of using the smaller chips would carry to the larger ones, just wanted to make sure.

I thought I saw an article on using the DS1302 alongside I2C, so I misinterpreted the datasheet. So if I use the DS1307 along side the 24LCxxx, I can do the interfaces to both with just 2 i/o?

KC8DKT

Thanks for the DS1307 info Forrest & dwegscheid. I did not know the 07 was I2C and has 56Bytes ram too boot.