data collection and storage.....

[Bernd Felsche]

Chris Conlon tapped away at the keyboard with:

> At 06:44 AM 9/1/00 +0200, =?US-ASCII?Q?Jorgen_Karlsson?= wrote:
> >> The 8535 is unable to directly address external storage as it has no
> >> external address bus. However, the SPI can be used to talk directly
> >> to serial flash-type storage chips - though development of such a
> >> facility is perhaps beyond what you think are you limits.
> >
> >Lots of code snippets are available for Bascom, most likely a SPI eeprom
> >example are available. ....time has passed five minuits to be exact.... I
> >found a I2C eeprom example, http://www.mcselec.com/download/avr/samples.zip.
> >i2c.bas is the file you want to check out.  The small footprint of the

> If you're choosing between I2C eeproms and SPI eeproms, and you care
> about size, it'd be wise to check what's available in what size. I've
> been working with Microchip and Atmel. Both have about the same max
> size part in I2C, 256k bits. Microchip's biggest SPI part is only 64k
> bits, but Atmel has SPI parts up to 1M bits. Note that most if not
> all of the larger parts are page write only (you must write in 32-64-128
> byte blocks), so if you're on a very tight RAM budget this may be a
> consideration. The smaller parts typically allow you to write any
> contiguous block of bytes that fits within a single page, which can be
> a lot more convenient.

Atmel's 16Mbit AT45DB161 for SPI has two SRAM buffer pages (528bytes
each), allowing you to contnue writing to one while the other is
being flashed (7ms/page). The part can be clocked at up to 13MHz.
i.e.  roughly 10Mbps (that's _bits/second_) peak storage rate or
600kbps sustained. 

The only precaution you moght take is to ensure that dirty buffers
are flashed before removing power. Perhaps using brown-out detection
preferably, with something like a 'super-cap' to provide sufficient
energy to write in case power gets removed inadvertantly.

-- 
Bernd Felsche - Innovative Reckoning
Perth, Western Australia
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