Maxim Integrated DS4830A Optical Microcontroller - Manual (Page 20)

DS4830A User’s Guide
20
2.4.4.2 – Memory Map When Executing from Utility ROM
When executing from the utility ROM:
• Read and write operations of SRAM memory are executed normally.
• Reading of flash memory is executed normally. Writing to flash memory requires the use of the utility ROM
routines.
• One page (byte access mode) or both pages (word access mode) of the flash memory can be accessed as data
with an offset of 8000h as determined by the CDA0 bit.
Figure 2-4 illustrates the mapping of the SRAM and flash memory segments into data memory space when code is
executing from the utility ROM memory segment.
2K * 16
SRAM
16K * 16
FLASH
(SEGMENT 0)
4K * 16
UTILITY ROM
PROGRAM
SPACE
16K * 16
FLASH
(SEGMENT 1)
0000h
3FFFh
4000h
7FFFh
8FFFh
A000h
A7FFh
FFFFh
8000h
32K * 8
LOWER HALF
(SEGMENT 0)
OF FLASH
4K * 8
SRAM
DATA SPACE
(BYTE MODE,
CDA0 = 0)
0000h
FFFFh
8000h
32K * 8
UPPER HALF
(SEGMENT 1)
OF FLASH
0000h
FFFFh
8000h
0FFFh
DATA SPACE
(BYTE MODE,
CDA0 = 1)
4K * 8
SRAM
0FFFh
EXECUTING FROM
32K * 16
FLASH
0000h
FFFFh
8000h
DATA SPACE
(WORD MODE)
2K * 16
SRAM
07FFh
Figure 2-4: Memory Map When Executing from Utility ROM