DS5003 Datasheet, PDF (20/24 Pages) Maxim Integrated Products – Secure Microprocessor Chip

Secure Microprocessor Chip
be read out and transmitted back to the host PC in
decrypted form. Similarly, execution of the Verify com-
mand within the same bootstrap session causes the
incoming absolute hex data to be compared against
the true contents of the encrypted SRAM, and the CRC
command returns the CRC value calculated from the
true contents of the encrypted SRAM. As long as any of
these commands are executed within the same boot-
strap session, the loaded key value remains the same
and the contents of the encrypted program/data SRAM
can be read or written normally and freely until the
security lock bit is set.
When the security lock bit is set using the Z command,
no further access to the true SRAM contents is possible
using any bootstrap command or by any other means.
A more extensive explanation of the serial loader opera-
tion can be found in the Secure Microcontroller User’s
Guide (www.maxim-ic.com/SecureUG).
Instruction Set
The DS5003 executes an instruction set that is object-
code compatible with the industry-standard 8051
microcontroller. As a result, software development
packages such as assemblers and compilers that have
been written for the 8051 are compatible with the
DS5003. A complete description of the instruction set
and operation is provided in the Secure Microcontroller
User’s Guide.
Memory Organization
Figure 10 illustrates the memory map accessed by the
DS5003. The entire 64kB of program and 64kB of data
are potentially available to the byte-wide bus. This pre-
serves the I/O ports for application use. The user con-
trols the portion of memory that is actually mapped to
the byte-wide bus by selecting the program range and
data range. Any area not mapped into the SRAM is
FFFFh
PROGRAM RANGE
PROGRAM MEMORY
DATA MEMORY (MOVX)
64kB
DATA RANGE
NV RAM
PROGRAM
NV RAM
DATA
0000h
LEGEND:
= BYTE-WIDE BUS ACCESS (ENCRYPTED)
= EXPANDED BUS (PORTS 0 AND 2)
Figure 10. Memory Map in Nonpartitionable Mode (PM = 1)
= NOT AVAILABLE
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