MC68HC908AP16CFB datasheet(177/440 Pages) MOTOROLA

177 / 440 page

Monitor ROM (MON)

ROM-Resident Routines

MC68HC908AP Family — Rev. 2.5

Data Sheet

MOTOROLA

177

When the user dedicates a page of FLASH for data storage, and the size

of the data array defined, each call of the EE_WRTIE routine will

automatically transfer the data in the data array (in RAM) to the next

blank block of locations in the FLASH page. Once a page is filled up, the

EE_WRITE routine automatically erases the page, and starts reuse the

page again. In the 512-byte page, an 9-byte control block is used by the

routine to monitor the utilization of the page. In effect, only 503 bytes are

used for data storage. (see Figure 10-10). The page control operations

are transparent to the user.

Figure 10-10. EE_WRITE FLASH Memory Usage

When using this routine to store a 8-byte data array, the FLASH page

can be programmed 62 times before the an erase is required. In effect,

the write/erase endurance is increased by 62 times. When a 15-byte

data array is used, the write/erase endurance is increased by 33 times.

Due to the FLASH page size limitation, the data array is limited from 7

bytes to 15 bytes.

The coding example below uses the $EE00–$EFFF page for data

storage. The data array size is 15 bytes, and the bus speed is

4.9152 MHz. The coding assumes the data block is already loaded in

RAM, with the address pointer, FILE_PTR, pointing to the first byte of the

data block.

PAGE BOUNDARY

CONTROL: 9 BYTES

DATA ARRAY

PAGE BOUNDARY

ONE PAGE = 512 BYTES

F L ASH

Freescale Semiconductor, Inc.

For More Information On This Product,

Go to: www.freescale.com

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