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10. Supported Flash Memories

There are several flash memories that have been qualified for use with the Rabbit 4000 microprocessor. Both small and large sector flash devices are supported. To incorporate a large-sectored flash into an end product, the best strategy is have a small-sectored development board.

Table 10-1 Flash Devices for Rabbit 4000-Based Designs

Device Name	Device Size (bytes)	Write Mode	Operating Voltage	Dynamic C Support
SST39LF040	512x8	byte	3.0-3.6V	Starts w/ version 10
SST39VF040-70-41	512x8	byte	2.7-3.6V	Starts w/ version 10
SST39LF040-45-4C	512Kx8	byte	3.0-3.6V	Starts w/ version 10
SST39LF400A-55-4C	256Kx16	word	3.0-3.6V	Starts w/ version 10
SST39LF800A-55-4C	512Kx16	word	3.0-3.6V	Starts w/ version 10

10.1 Supporting Other Flash Devices

Rabbit does not support flash devices other than those listed in Table 10-1. However, if you wish to use another flash memory, one that still uses the same standard 8-bit JEDEC write sequences as one of the supported flash devices, the existing Dynamic C flash libraries may be able to support it simply by modifying a few values. Not all flash devices can be supported, and the degree of support will vary depending on the flash characteristics.

There are two modifications to be made, depending on the version of Dynamic C that you are using. Step through the list below and perform each action that corresponds to your flash type:

1. The flash device needs to be added to the list of known flash types. This table can be found by searching for the label FlashData in the file LIB\Rabbit4000\BIOSLIB\FLASHWR.LIB. The format is described in the file and consists of the flash ID code, the sector size in bytes, the total number of sectors, and the flash write mode.

   See the comments above the "FlashData::" table in FLASHWR.LIB for more information.

2. The same information that was added to the FlashData table needs to be added to the FLASH.INI file (in the main directory where Dynamic C was installed) for use by the compiler and pilot BIOS. See the top of the file for more information.

10.2 Writing Your Own Flash Driver

Rabbit does not support using a flash memory that is not listed above and that does not use the same standard 8-bit JEDEC write sequences as one of the supported flash memories. If you must use such a flash memory, the flash driver supplied with Dynamic C (LIB\Rabbit4000\BIOSLIB\FLASHWR.LIB) provides a model for writing your own flash driver.