DataFlash
From Wikipedia, the free encyclopedia
DataFlash is a low pin-count serial interface for flash memory. It is an Atmel proprietary interface, compatible with the SPI standard.
Information is written and read from a DataFlash chip using any microcontroller, such as the Microchip PIC or the ARM.
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[edit] Examples of DataFlash
The AT45DB161D chip is an example of a 2Mb dataflash chip available from Atmel. This chip comes in a 6x6mm SO-8 package. This chip is used in a huge number of consumer electronic products. Any microcontroller can use this chip to store data.
[edit] Should I use DataFlash or EEPROM?
Both DataFlash and EEPROM chips can be accessed from a microcontroller, using a 3-wire SPI bus.
From the product developers point of view, EEPROM is very simple to use. To use EEPROM, bytes are written or read, via SPI, one byte at a time.
From the product developers point of view, DataFlash is more complex to use. To use DataFlash, bytes are written via SPI to an internal RAM buffer contained within the DataFlash chip. This RAM buffer typically either 264 or 528 bytes. The contents of the RAM buffer are then written to flash, triggered by a special SPI command. Data is read back using the same method in reverse.
DataFlash generally has a higher capacity than EEPROM. DataFlash capacities in a 6x6mm SO-8 package range from 256Kb to 8Mb, while EEPROM capacities in a 6x6mm SO-8 package range from 4Kb to 512Kb.
In summary, if a design requires more data storage than EEPROM can offer, use DataFlash. Otherwise, use EEPROM, as the programming code required to interface to the DataFlash chip will be simpler.
[edit] Example C source code to interface to DataFlash
A free example of PIC microcontroller source code in C, that can be used to interface to any DataFlash chip, is available from www.microchipC.com.
