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DataFlash is a low pin-count serial interface for 
DataFlash is a low pin-count serial interface for flash memory
Flash memory is an Integrated circuit, electronic Non-volatile memory, non-volatile computer memory storage medium that can be electrically erased and reprogrammed. The two main types of flash memory, NOR flash and NAND flash, are named for t ...
.
It was developed as an Atmel proprietary interface, compatible with the SPI standard. In October 2012, the AT45 series DataFlash product lines, related intellectual property, and supporting employee teams were purchased by Adesto Technologies.
Information is written and read from a DataFlash device using any microcontroller, such as the Atmel AVR
AVR is a family of microcontrollers developed since 1996 by Atmel, acquired by Microchip Technology in 2016. They are 8-bit RISC single-chip microcontrollers based on a modified Harvard architecture. AVR was one of the first microcontroller ...
, the Microchip PIC or the ARM. The boot ROM
Boot ROM is a piece of read-only memory (ROM) that is used for booting a computer system. It contains instructions that are run after the CPU is reset to the reset vector, and it typically loads a bootloader. There are two types of boot ROM: ...
of numerous Atmel ARM microcontrollers support downloading code from DataFlash chips after reset.
Examples
The AT45DB161DIntegrated circuit
An integrated circuit (IC), also known as a microchip or simply chip, is a set of electronic circuits, consisting of various electronic components (such as transistors, resistors, and capacitors) and their interconnections. These components a ...
(chip) is an example of a 2 MB (16 Mbit) dataflash product. This comes in a 8x5 mm small outline integrated circuit 8-pin package. This chip is used in a huge number of consumer electronic products. Any microcontroller can use this chip to store data.
The AT45DCB008D card is an 8 MB (64 Mbit) flash memory card, which could be mistaken for an MMC or SD card. This DataFlash card packages an AT45DB642D flash chip, which is also available in 8x6 mm CASON 8-pin packages.
The AT26 series DataFlash chips are software-incompatible with the original AT45 series chips. They use a simpler command set, supported by other vendors of serial flash but omitting SRAM buffers and other features that make AT45 chips simpler to support.
Comparisons
Both DataFlash andEEPROM
EEPROM or E2PROM (electrically erasable programmable read-only memory) is a type of non-volatile memory. It is used in computers, usually integrated in microcontrollers such as smart cards and remote keyless systems, or as a separate chip d ...
chips can be accessed from a microcontroller, using a 4-wire Serial Peripheral Interface Bus
Serial Peripheral Interface (SPI) is a de facto standard (with many #Variations, variants) for Comparison of synchronous and asynchronous signalling, synchronous serial communication, used primarily in embedded systems for short-distance wired c ...
(SPI bus). Both are available in small 8 pin packages. The protocol interfaces are very similar; in both cases, byte
The byte is a unit of digital information that most commonly consists of eight bits. Historically, the byte was the number of bits used to encode a single character of text in a computer and for this reason it is the smallest addressable un ...
s are written or read, via SPI, one or more bytes at a time.
DataFlash usually had higher capacities than EEPROM in the early days, and it still provides faster access times. DataFlash capacities in small packages range from 128 kB to 8 MB, while SPI EEPROM capacities in similar packages range from 1 kB to 8 MB .
Flash chips are tuned for page access, rather than the byte access used with EEPROM.
However, AT45 series chips have commands that let their drivers act more like EEPROM drivers.
Leveraging the SRAM buffers exposed by AT45 chips to do more than support EEPROM-like access requires specialized software.
DataFlash cards are more expensive than the consumer oriented MMC or SD cards, and have lower capacities, but have an extremely simple programming interface compared to MMC/SD. All these cards can be used in SPI mode.
In summary, DataFlash enables use of more data storage and faster access times than EEPROM. DataFlash chips can leverage the AT45 SRAM buffers. EEPROMs, AT26 series chips, or MMC/SD cards permit use of second sources for parts.
For cards used in field upgrades, DataFlash cards permit simple software support and compatibility with on-board flash chips; MMC/SD costs less.
The programming code required to interface EEPROM to the DataFlash chip is simpler.
Programming
Examples of source code in theC programming language
C (''pronounced'' '' – like the letter c'') is a general-purpose programming language. It was created in the 1970s by Dennis Ritchie and remains very widely used and influential. By design, C's features cleanly reflect the capabilities of ...
are available for operating systems such as BeRTOS, and eCos.
References
{{Reflist Non-volatile memory