Section 16 Program Loading - Mitsubishi DS907x SIP User Manual

USER'S GUIDE
SECTION 16: PROGRAM LOADING
INTRODUCTION
Program loading is performed to initialize the contents
of NV RAM and to configure the microcontroller. Load-
ing is done using a Bootstrap ROM Loader built into all
members of the Secure Microcontroller family. When
this Bootstrap Loader is invoked, the user's NV RAM
appears as data memory to the ROM and can therefore
be initialized. Once loading is complete, the Bootstrap
ROM then becomes transparent. It has no effect on the
user's memory map and is completely invisible. Boot-
strap Loading is normally done for the initial program
loading. There are no restrictions on using it for
upgrades or reprogramming, though it is possible using
the memory mapping features, to perform partial
reloads without invoking the loader.
The Bootstrap Loader is primarily used to initialize
memory, but it is capable of several other functions. It
can change the memory map configuration, dump or
verify the contents of memory, perform a CRC check, fill
a block with a constant, manipulate the security features
and the I/O ports. It can not display or edit the Scratch-
pad RAM (128 bytes) or SFRs since it uses these
resources for its own operation. Note that the Scratch-
pad RAM will be erased by the loader. Therefore the
loader should not be invoked while critical data is stored
in this area. The MOVX RAM area will not be altered by
the loader unless a user requests that this be done.
Each version of microcontroller has different loader
modes and different commands. All versions are capa-
ble of being programmed via the serial port and this is
the preferred method. The DS5000 series is also capa-
ble of a parallel programming technique similar to an
EPROM–based 8051. The DS5001/DS5002 series
supports an alternate parallel load mode that is for use
by a host microprocessor using the 8042–type RPC
mode. The following discussions explain the methods of
invoking the Bootstrap Loader. Then the different pro-
gramming modes are described. The remaining sec-
tions give a detailed description of the commands and
syntax used by the Bootstrap ROM.
The DS5000 series [DS5000(T), DS2250T, and
DS5000FP] and the DS5001/2 series [DS5001FP,
DS2251T, DS5002FP, DS2251T] have different pro-
gram loading modes available. The DS5000 series can
be loaded via its serial port or in a parallel fashion like an
EPROM type 87C51. The serial mode allows the
DS5000 to be programmed in a fixture or while installed
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in the end system. The parallel method requires a
super–voltage and is normally done in a fixture only. The
DS5001 series has a similar serial mode with the same
benefits. The parallel mode is entirely different. The
DS5001FP or DS5002FP, using its RPC slave interface,
can be loaded in a parallel manner by a host micropro-
cessor. This is also an in–system technique but could be
performed in a fixture. It requires no super–voltage
pulses. Note that this mode is a high–speed loader and
bears no resemblance to an 87C51 load mode.
Note: Dallas Semiconductor highly recommends
that serial load capability be designed into the tar-
get system. This provides substantial flexibility to
upgrade and troubleshoot the system. Using in–system
serial loading allows a product to take full advantage of
the Secure Microcontroller's features.
INVOKING THE BOOTSTRAP LOADER
The Secure Microcontroller defaults to normal operating
(non–loader) mode without external hardware. If the
loader mode is desired, it can be invoked at any time
using the methods described later in this section. Once
the Bootstrap Loader session is complete, the device
will perform a hardware reset and begin operation. This
will be identical to an external reset, except that the
bootstrap loader, as part of normal operation, will modify
various locations in scratchpad RAM. The following
table shows which areas of scratchpad RAM are guar-
anteed destroyed, guaranteed preserved, or will be of
indeterminate state after exiting the bootstrap loader.
Guaranteed Preserved
Indeterminate
Guaranteed Destroyed
The guaranteed preserved locations are areas in
scratchpad RAM that will not be changed by the boot-
strap loader. These locations as useful for storing data
such as serial numbers, which should be retained
regardless of the software. Similarly, the guaranteed
destroyed locations have all been overwritten during
bootstrap loader execution with indeterminate data.
These locations can be used to store security–sensitive
data, because it will be erased by the loader before
another program can read it out.
130
DS5000FP DS5001/2FP
None 70h–7Fh
None 38h–6Fh
00h–7Fh 0h–37h