MAX31782_11 Datasheet, PDF (11/20 Pages) Maxim Integrated Products – System Management Microcontroller

System Management Microcontroller
SYSTEM
REGISTERS
8h
AP
9h
A
Bh
PFX
Ch
IP
Dh
SP
Eh
DPC
Fh
DP
00h
0Fh
PERIPHERAL
REGISTERS
0h
M0
1h
M1
2h
M2
3h
M3
4h
M4
5h
M5
00h
1Fh
0Fh
16 x 16
STACK
00h
FFFFh
PROGRAM
MEMORY SPACE
8FFFh
8000h
7FFFh
4K x 16
UTILITY ROM
32K x 16
USER PROGRAM
MEMORY
001Fh
0010h
0000h
PASSWORD
FFFFh
DATA MEMORY
(BYTE MODE)
9FFFh
8000h
8K x 8
UTILITY ROM
07FFh
0000h
2K x 8
SRAM DATA
FFFFh
DATA MEMORY
(WORD MODE)
8FFFh
8000h
4K x 16
UTILITY ROM
03FFh
0000h
1K x 16
SRAM DATA
Figure 3. Memory Map
The memory is implemented using the Harvard archi-
tecture, with separate address spaces for program
and data memory. A pseudo-Von Neumann memory
map is also used placing ROM, application code, and
data memory into a single contiguous memory map.
The pseudo-Von Neumann memory map allows data
memory to be mapped into program space, permitting
code execution from data memory. In addition, program
memory can be mapped into data space, permitting
code constants to be accessed as data memory. Figure
3 shows the device’s memory map when executing from
program memory space. Refer to the MAX31782 User’s
Guide for memory map information when executing from
data or ROM space.
The incorporation of flash memory allows field upgrade
of the firmware. Flash memory is password protected
with a 16-word key, denying access to program memory
by unauthorized individuals.
Utility ROM
The utility ROM is a 4KWord block of internal ROM
memory that defaults to a starting address of 8000h. The
utility ROM consists of subroutines that can be called
from application software. These include the following:
• In-system programming (bootstrap loader) over JTAG
or I²C-compatible interfaces
• In-circuit debug routines
• Callable routines for in-application flash programming
Following any reset, execution begins in the utility ROM.
The ROM software determines whether the program
execution should immediately jump to location 0000h,
the start of application code, or to one of the special
routines mentioned. Routines within the utility ROM are
firmware-accessible and can be called as subroutines
by the application software. More information on the util-
ity ROM contents is contained in the MAX31782 User’s
Guide.
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