DS4830 Datasheet, PDF (18/29 Pages) Maxim Integrated Products – Optical Microcontroller 16-Bit MAXQ20 Low-Power Microcontroller

DS4830
Optical 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
0000h
FFFFh
DATA MEMORY
(BYTE MODE)
8FFFh
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 6. Memory Map
• Internal self-test 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 utility
ROM contents is contained in the DS4830 User’s Guide.
Password
Some applications require protection against unau-
thorized viewing of program code memory. For these
applications, access to in-system programming, in-appli-
cation programming, or in-circuit debugging functions
is prohibited until a password has been supplied. The
password is defined as the 16 words of physical program
memory at addresses 0010h–001Fh.
A single password lock (PWL) bit is implemented in
the device. When the PWL is set to 1 (power-on-reset
default) and the contents of the memory at addresses
0010h–001Fh are any value other than all FFh or 00h, the
password is required to access the utility ROM, includ-
ing in-circuit debug and in-system programming routines
that allow reading or writing of internal memory. When
PWL is cleared to 0, these utilities are fully accessible
without the password. The password is automatically set
to all ones following a mass erase.
Detailed information regarding the password can be
found in the DS4830 User’s Guide.
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