Mitsubishi Motors DS5000TK - Manual (Page 23)

USER’S GUIDE
050396 22/173
23
DS5001/DS5002 SERIES RPCTL REGISTER BITS AFFECTING MEMORY Figure 4–9
RNR ––– EXBS AE IBI DMA RPCON RG0
Bit Description:
RPCTL.5: EXBS
The Expanded Bus Select routes data memory access (MOVX) to the
Expanded bus formed by ports 0 and 2 when set.
Initialization: Cleared after all resets.
Read Access: Can be read at any time.
Write Access: Can be written at any time.
RPCTL.4: AE
Access Enable is used when a software reload is desired without using
Program Load mode. When set, the DS5001 will be temporarily configured
in a Partitionable configuration with the partition at 4K. This will occur even
if the PM=1. When cleared, the prior memory configuration is resumed.
Initialization: Cleared after all resets.
Read Access: Can be read at any time.
Write Access: Can be written at any time, timed access protected.
RPCTL.0: RG0
This is a Range bit which is used to determine the size of the program
memory space. Its usage is shown above.
Initialization: Unaffected by watchdog, external, or power–up resets. Cleared on a No V
LI
reset or clearing of the security lock.
Read Access: Can be read at any time.
Write Access: Cannot be modified by the application software. Can only be written during
Program Load.
Loading and Reloading Program Memory
Soft Microcontrollers are programmed through a built–
in Bootstrap Loader function. This loader is also used to
configure the desired options for memory map control.
The Secure Microcontroller uses its low power lithium
backed circuits to maintain critical settings in the ab-
sence of power. For this reason, it is not necessary to set
the Partition, Range, etc. after every power–up or reset.
Once set, they will remain unless deliberately modified.
Bootstrap Loading is discussed in a later section. One
of the major advantages of a Secure Microcontroller is
the ability to change these settings, and even reload the
entire program memory while the device is installed in
system. To completely re–program and re–configure a
device, the Bootstrap Loader must be invoked. Howev-
er, the Secure Microcontroller is designed to allow a
partial reload of memory without invoking the Bootstrap
Loader.
The major advantage of this technique is that it requires
no hardware or external switches. Most of the memory
can be reprogrammed under application software con-
trol. It would commonly be used when the target system
connects to a PC through a serial port as part of an ap-
plication. For example, a data logger that must dump
memory periodically. While connected to the PC, it is
extremely easy to reload portions of memory using the
“Soft Reload”.