NOR Flash

SafeFLASH is designed to support all types of standard NOR flash.

 

NOR flash is one of the basic building blocks of most embedded systems. It is used to store non-volatile data and code. NOR flash must be erased prior to writing. Erase times are relatively long.

 

Flash devices suffer when over-used. If a particular block is used beyond the manufacturer's specification the block may eventually develop errors. To combat this, wear-level algorithms are implemented to ensure level usage of the blocks. In addition, SafeFLASH’s method of recording changes to the file descriptors ensures that the minimum amount of writing is done.

 

Bad blocks may develop in a device over time. These are automatically detected and are paged out of the file system.

 

It is sometimes necessary to reserve sections of a flash device for particular purposes outside of the file system. This is achieved by specifying in the driver which of the available blocks are for "private" use. The standard low-level read/write/erase routines can still be used for accessing these blocks.

 

Multiple flash devices may be used in a system either in parallel, to widen the data bus and achieve higher performance, or in series to increase storage size. This behavior is fully supported by SafeFLASH and relies only on configuration changes to the drivers.

 

Provided with the system is a range of sample drivers for various flash devices from different manufacturers. The sample drivers are carefully documented in the Developer's Guide to allow easy porting to whatever chip/hardware configuration is required.

 

Literally thousands of NOR flash devices are available, all with slightly different characteristics but retaining the same base properties. SafeFLASH supports all known manufacturers’ devices including:

Sample drivers are provided for a number of these devices.