Datasheet

DS4830
Optical Microcontroller
19Maxim Integrated
Figure 6. Memory Map When Program is Executing from Flash Memory
• 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.
SYSTEM
REGISTERS
PERIPHERAL
REGISTERS
DP
16 x 16
STACK
M5
M4
M3
M2
M1
M0
5h
0Fh
00h
4h
3h
2h
1h
0h
FFFFh FFFFh FFFFh
8FFFh9FFFh8FFFh
7FFFh
0000h
0000h 0000h
4K x 16
UTILITY ROM
8K x 8
UTILITY ROM
4K x 16
UTILITY ROM
2K x 8
SRAM DATA
1K x 16
SRAM DATA
32K x 16
USER PROGRAM
MEMORY
8000h 8000h 8000h
07FFh 03FFh
DPC
SP
IP
PFX
A
AP
Fh
00h 0Fh
00h 1Fh
Eh
Dh
Ch
Bh
9h
8h
PROGRAM
MEMORY SPACE
DATA MEMORY
(BYTE MODE)
DATA MEMORY
(WORD MODE)
001Fh
0010h
PASSWORD