XC2200 Derivatives
System Units (Vol. 1 of 2)
Startup Configuration and Bootstrap Loading
User’s Manual
10-8
V2.1, 2008-08
SCFG/BSL, V1.3
10.3.2
Support for Power-saving Modes
XC2200 allows several power-saving modes - for information about these modes and
how they can be controlled by user software refer to XC2000 Programmer’s Guide.
One rule regarding power-system handling in XC2200 is: if a power-state is entered with
DMP_1 supply below the minimum value at which the Flash is operable, this state must
be exited only by power-on (wake-up from power-save mode) but not by a functional
reset.
bit is defined to support application-compliance with this rule as follows:
•
is set upon device restart; AND
•
this restart is caused by a functional (not power-on) reset
the start-up procedure terminates and device enters
Therefore the user software controlling the power-states must:
1. before to enter a power-state in which Flash is not operable - set
2. after exiting this power-state (Flash not operable) by power-on in DMP_1 - reset
.
Note: After power-on in DMP_M the
bit as the complete
register will be
anyway reset.
10.3.3
Preparing to activate Parity
XC2200 supports parity as memory content protection mechanism, which can request
trap or reset upon a single-bit data error (refer to
).
The user software must activate parity trap/reset generation for any one of PSRAM,
DSRAM and DPRAM only after every location from the respective memory is written at
least once after the last power reset. In other words, parity must be activated for a
memory only after this memory has been initialized.
Note: The RAMs in USIC and MultiCAN modules implement special access mechanism,
which assures a memory location will be read only after it has been written before,
therefore for these memories no initialization is necessary.
The parity can be activated by user software using the sequence shown at
•
if
[15]=0 after power-on in DMP_1 (indicated by
SCU_RSTSTAT1.ST1=11
B
) - RAM initialization is needed and not been requested:
– optionally - if the application will run with system clock faster than 10MHz (system
frequency after power-on) - the clock reconfiguration can be done still here to use
increased speed for a faster RAM initialization;
– install request for RAMs initialization by setting
[15:11]=10111
B
;
It is also possible to set selectively only some of the bits[13:11] corresponding to