20-101-1051 Datasheet, PDF(44/165 Page) List of Unclassifed Manufacturers – C-Programmable Core Module with NAND Flash Mass Storage and Ethernet

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20-101-1051 Datasheet, PDF (44/165 Pages) List of Unclassifed Manufacturers – C-Programmable Core Module with NAND Flash Mass Storage and Ethernet

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4.4 Memory

4.4.1 SRAM

RCM3365/RCM3375 boards have 512K of program-execution fast SRAM at U11. The

program-execution SRAM is not battery-backed. There are 512K of battery-backed data

SRAM installed at U10.

4.4.2 Flash EPROM

RCM3365/RCM3375 boards also have 512K of flash EPROM at U9.

NOTE: Rabbit recommends that any customer applications should not be constrained by

the sector size of the flash EPROM since it may be necessary to change the sector size

in the future.

Writing to arbitrary flash memory addresses at run time is also discouraged. Instead, use a

portion of the âuser blockâ area to store persistent data. The functions writeUser-

Block and readUserBlock are provided for this. Refer to the Rabbit 3000 Micropro-

cessor Designerâs Handbook and the Dynamic C Function Reference Manual for additional

information.

4.4.3 NAND Flash

The RCM3365 and the RCM3375 support a removable xD-Picture Cardâ¢ to store data and

Web pages. The RCM3365 and the RCM3375 both can handle up to a 128MB removable

xD-Picture Card, and the RCM3365 model also has a 32MB onboard NAND flash.*

NOTE: Rabbit-based systems do not implement the xD-Picture Cardâ¢ specification for

data storage, and are neither compatible nor compliant with xD-Picture Cardâ¢ card

readers.

The NAND flash and xD-Picture Card are particularly suitable for mass-storage applica-

tions, but are generally unsuitable for direct program execution. The NAND flash differs

from parallel NOR flash (the type of flash memory used to store program code on Rabbit-

based boards and RabbitCore modules currently in production) in two respects. First, the

NAND flash requires error-correcting code (ECC) for reliability. Although NAND flash

manufacturers do guarantee that block 0 will be error-free, most manufacturers guarantee

that a new NAND flash chip will be shipped with a relatively small percentage of errors,

and will not develop more than some maximum number or percentage of errors over its

rated lifetime of up to 100,000 writes. Second, the standard NAND flash addressing

method multiplexes commands, data, and addresses on the same I/O pins, while requiring

that certain control lines must be held stable for the duration of the NAND flash access.

The software function calls provided by Rabbit for the NAND flash take care of the data-

integrity and reliability attributes.

* RCM3365 modules sold before 2008 had 16MB fixed NAND flash memory.

RabbitCore RCM3365/RCM3375

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