AN2400 Freescale Semiconductor / Motorola, AN2400 Datasheet - Page 19

• Manufacturer Part Number: AN2400
• Description: HCS12 NVM Guidelines
• Manufacturer: Freescale Semiconductor / Motorola

Flash Memory
Paging
MOTOROLA
The Program Counter on the HCS12 family of microcontrollers is a 16-bit
register, which means that the directly addressable space is limited to 64k
bytes. Larger memory sizes are accessed by using a technique called paging,
or memory banks. As implemented on the HCS12 family, the entire flash
memory is divided into pages 16k bytes in size. One fixed page is always
accessible at $4000 to $7FFF and another fixed page is always accessible at
$C000 to $FFFF. The region of addresses from $8000 to $BFFF are
designated to be the page window. Individual pages of memory are accessible
through this window, the desired page being selected by means of the PPAGE
register. Only one complete page is accessible through the window at any time.
Figure 18
HCS12DP256.
REGISTER BASE + $10F
Freescale Semiconductor, Inc.
REGISTER BASE + $100
FLASH_START = $4000
FLASH_END = $FFFF
For More Information On This Product,
shows the memory map and memory paging scheme for the
Go to: www.freescale.com
$C000
$E000
$F000
$F800
$4200
$4400
$4800
$5000
$8000
HCS12 NVM Guidelines
12K
Figure 18. MC9S12DP256 Memory Map
16K PAGED
(16 bytes)
MEMORY
$3F
$3E
$FF00 - $FF0F, Flash Protection/Security Field
$38
Flash Registers
Flash Array
Flash Protected High Sectors
2K, 4K, 8K, 16K bytes
Flash Protected Low Sectors
0.5K, 1K, 2K, 4K bytes
$39
$30
$3A
Block 1
$31
Block 3
$3B
$32
$3C
$33
$3D
$34
$3E
Block 0
$35
Block 2
$3F
Flash Memory
$36
AN2400/D
$37
19